0 00:00:00,000 --> 00:00:30,000 Dear viewer, these subtitles were generated by a machine via the service Trint and therefore are (very) buggy. If you are capable, please help us to create good quality subtitles: https://c3subtitles.de/talk/415 Thanks! 1 00:00:09,180 --> 00:00:11,309 Yeah, so thank you and welcome 2 00:00:11,310 --> 00:00:13,469 to this last talk this 3 00:00:13,470 --> 00:00:14,470 evening. 4 00:00:15,160 --> 00:00:17,719 I think there will be a film at, what, 5 00:00:17,720 --> 00:00:18,809 zero o'clock? 6 00:00:18,810 --> 00:00:20,999 But the last talk for this 7 00:00:21,000 --> 00:00:23,099 evening is for Maxwell to 8 00:00:23,100 --> 00:00:24,109 antenna arrays. 9 00:00:25,860 --> 00:00:27,689 You probably all know Maxwell's 10 00:00:27,690 --> 00:00:30,239 equations, the four equations. 11 00:00:30,240 --> 00:00:32,669 I actually like the idea 12 00:00:32,670 --> 00:00:34,859 that with four more or less simple 13 00:00:34,860 --> 00:00:36,629 equations, you can't really explain a lot 14 00:00:36,630 --> 00:00:37,630 of stuff. 15 00:00:38,640 --> 00:00:41,009 And I'm a communication 16 00:00:41,010 --> 00:00:42,809 engineer, so I will stay in three 17 00:00:42,810 --> 00:00:44,259 dimensions. 18 00:00:44,260 --> 00:00:46,829 Um, back when I was studying, 19 00:00:46,830 --> 00:00:48,899 I actually also visited the lecture 20 00:00:48,900 --> 00:00:51,149 about relativistic electro 21 00:00:51,150 --> 00:00:53,249 dynamics, which is all this mix 22 00:00:53,250 --> 00:00:55,199 will in four dimensions. 23 00:00:55,200 --> 00:00:57,959 And I also I passed it 24 00:00:57,960 --> 00:00:59,009 somehow. 25 00:00:59,010 --> 00:01:01,259 But yeah, what you can see 26 00:01:01,260 --> 00:01:03,509 here on this nice 27 00:01:03,510 --> 00:01:05,969 picture is 28 00:01:05,970 --> 00:01:08,039 AM Broadcasting Station 29 00:01:08,040 --> 00:01:10,319 with an antenna 30 00:01:10,320 --> 00:01:10,949 array. 31 00:01:10,950 --> 00:01:13,439 I think it was medium wave here 32 00:01:13,440 --> 00:01:14,759 in Brazil. 33 00:01:14,760 --> 00:01:17,189 It was I think in previous Apollo 34 00:01:17,190 --> 00:01:19,259 I was for more working with stuff 35 00:01:19,260 --> 00:01:20,819 like this. 36 00:01:20,820 --> 00:01:22,739 At the moment I work as a science 37 00:01:22,740 --> 00:01:24,809 journalist and 38 00:01:24,810 --> 00:01:26,969 it's quite interesting how a lot of 39 00:01:26,970 --> 00:01:29,669 stuff like mobile broadband and also 40 00:01:29,670 --> 00:01:31,769 things like radio astronomy are 41 00:01:31,770 --> 00:01:34,139 coming together and the field of antenna 42 00:01:34,140 --> 00:01:36,389 arrays. So I will get the 43 00:01:36,390 --> 00:01:38,789 the topic to this. 44 00:01:38,790 --> 00:01:41,129 And also, I think for everybody some 45 00:01:41,130 --> 00:01:43,439 fundamentals of propagation 46 00:01:43,440 --> 00:01:45,629 and how antennas are working, which now 47 00:01:45,630 --> 00:01:48,779 everybody has his or her package. 48 00:01:48,780 --> 00:01:50,909 It's very handy in many situations. 49 00:01:52,230 --> 00:01:54,389 So here are 50 00:01:54,390 --> 00:01:56,009 four Mexi equations. 51 00:01:56,010 --> 00:01:57,239 We have got law. 52 00:01:57,240 --> 00:01:59,249 We have Koslov for magnetism. 53 00:01:59,250 --> 00:02:01,529 We have the of induction, Faraday's 54 00:02:01,530 --> 00:02:04,049 law of induction, I think. 55 00:02:04,050 --> 00:02:06,839 Could it be that this microphone is on? 56 00:02:06,840 --> 00:02:08,758 No. OK, good. 57 00:02:08,759 --> 00:02:10,948 Um, and the fourth one 58 00:02:10,949 --> 00:02:13,110 is Amperes Circuit Law here. 59 00:02:14,190 --> 00:02:16,889 Um, a bit more details. 60 00:02:16,890 --> 00:02:18,959 So Gauss law 61 00:02:18,960 --> 00:02:21,179 of induction actually 62 00:02:21,180 --> 00:02:23,579 describes the relationship between 63 00:02:23,580 --> 00:02:25,739 a static electric field and 64 00:02:25,740 --> 00:02:28,079 the electric charges that caused 65 00:02:28,080 --> 00:02:30,959 it. So here we have to 66 00:02:30,960 --> 00:02:32,310 point of charges 67 00:02:33,720 --> 00:02:35,789 and the static electric field points 68 00:02:35,790 --> 00:02:38,039 away from the positive charge on 69 00:02:38,040 --> 00:02:40,139 this side here towards the negative 70 00:02:40,140 --> 00:02:41,159 charge. 71 00:02:41,160 --> 00:02:44,849 And very easy example as a capacitor. 72 00:02:44,850 --> 00:02:45,779 You all know this. 73 00:02:45,780 --> 00:02:47,909 You have your two two sides of 74 00:02:47,910 --> 00:02:50,069 the capacitor where the charges 75 00:02:50,070 --> 00:02:52,139 are, and then you have the electric field 76 00:02:52,140 --> 00:02:54,359 in between a little bit of 77 00:02:54,360 --> 00:02:55,139 mathematics. 78 00:02:55,140 --> 00:02:57,239 So here we have the this 79 00:02:57,240 --> 00:02:59,669 knob operator with the C that 80 00:02:59,670 --> 00:03:01,679 the divergence of a vector. 81 00:03:03,210 --> 00:03:05,669 It's a derivate of each value, 82 00:03:05,670 --> 00:03:07,859 um, in in space or in 83 00:03:07,860 --> 00:03:10,739 X, Y and Z coordinates, 84 00:03:10,740 --> 00:03:12,989 and then they are added up. 85 00:03:12,990 --> 00:03:15,329 So actually this measures 86 00:03:15,330 --> 00:03:17,759 the magnitude of a vector fields 87 00:03:17,760 --> 00:03:20,669 source I think at a given point. 88 00:03:20,670 --> 00:03:22,949 And if we let come on to free space 89 00:03:22,950 --> 00:03:25,199 propagation this role 90 00:03:25,200 --> 00:03:27,329 here. So we have no charges and 91 00:03:27,330 --> 00:03:29,639 free space. So this row becomes 92 00:03:29,640 --> 00:03:32,279 zero and we can simplify this 93 00:03:32,280 --> 00:03:33,280 equation. 94 00:03:34,590 --> 00:03:36,629 So the next one goes off. 95 00:03:36,630 --> 00:03:38,879 A magnetism is the divergent 96 00:03:38,880 --> 00:03:40,889 of the magnetic flux. 97 00:03:40,890 --> 00:03:42,659 Density equals zero 98 00:03:43,830 --> 00:03:45,959 that states that they are no 99 00:03:45,960 --> 00:03:48,239 magnetic charges or 100 00:03:48,240 --> 00:03:50,309 magnetic monopoles. 101 00:03:50,310 --> 00:03:52,499 You all probably know what happens 102 00:03:52,500 --> 00:03:54,599 if you break a magnet 103 00:03:54,600 --> 00:03:56,459 into two parts. 104 00:03:56,460 --> 00:03:58,739 So you get two magnets 105 00:03:58,740 --> 00:04:00,480 with a plus and minus pole. 106 00:04:01,810 --> 00:04:04,389 Um, yeah, the 107 00:04:04,390 --> 00:04:06,599 the equations state that the magnetic 108 00:04:06,600 --> 00:04:07,589 field lines. 109 00:04:07,590 --> 00:04:10,289 So the circles here 110 00:04:10,290 --> 00:04:12,599 neither begin nor end that make loops 111 00:04:12,600 --> 00:04:14,490 or extend to infinity and back. 112 00:04:18,829 --> 00:04:21,109 The third one is Paradise Lost, 113 00:04:21,110 --> 00:04:24,049 and actually this one describes 114 00:04:24,050 --> 00:04:26,659 how a time varying magnetic field 115 00:04:26,660 --> 00:04:28,759 creates or induces 116 00:04:28,760 --> 00:04:29,989 an electric field. 117 00:04:31,190 --> 00:04:33,379 This lengthily term here 118 00:04:33,380 --> 00:04:35,479 is the kernel of a 119 00:04:35,480 --> 00:04:36,319 vector. 120 00:04:36,320 --> 00:04:38,719 This actually describes the direction. 121 00:04:38,720 --> 00:04:41,179 So it's the direction 122 00:04:41,180 --> 00:04:43,459 which is like orthogonal to the other 123 00:04:43,460 --> 00:04:44,460 one's. 124 00:04:45,120 --> 00:04:48,079 A good example is 125 00:04:48,080 --> 00:04:50,329 where this law is working 126 00:04:50,330 --> 00:04:53,269 is an electric generator. 127 00:04:53,270 --> 00:04:55,669 So, for example, it has a rotating 128 00:04:55,670 --> 00:04:57,949 bar magnet which creates 129 00:04:57,950 --> 00:05:00,229 a changing magnetic field 130 00:05:00,230 --> 00:05:02,479 and which in turn generates 131 00:05:02,480 --> 00:05:05,029 an electric field and nearby wire. 132 00:05:05,030 --> 00:05:07,549 So you get your electricity by moving 133 00:05:07,550 --> 00:05:08,689 your magnetic field. 134 00:05:10,980 --> 00:05:13,229 And the last equation 135 00:05:13,230 --> 00:05:15,329 here is pure pass 136 00:05:15,330 --> 00:05:17,999 law with MEXT Worth, Ed. 137 00:05:18,000 --> 00:05:20,069 and this one state that magnetic 138 00:05:20,070 --> 00:05:22,679 fields can be generated in two ways. 139 00:05:22,680 --> 00:05:25,589 One way is by electrical current. 140 00:05:25,590 --> 00:05:27,779 And this was the original Amperes 141 00:05:27,780 --> 00:05:29,009 law. 142 00:05:29,010 --> 00:05:31,229 And Maxwells addition 143 00:05:31,230 --> 00:05:33,299 then added 144 00:05:33,300 --> 00:05:35,369 that also by changing electric 145 00:05:35,370 --> 00:05:36,370 field, 146 00:05:38,040 --> 00:05:40,479 a magnetic field can be generated. 147 00:05:40,480 --> 00:05:41,459 And this addition. 148 00:05:41,460 --> 00:05:44,069 So this is this part here like the 149 00:05:44,070 --> 00:05:46,289 the if fear the electric field, 150 00:05:46,290 --> 00:05:48,289 they're related to the time. 151 00:05:48,290 --> 00:05:50,609 So the change of the electric field, 152 00:05:51,720 --> 00:05:54,509 this is especially important 153 00:05:54,510 --> 00:05:56,729 because it shows that not only 154 00:05:56,730 --> 00:05:58,889 does a changing magnetic field induce an 155 00:05:58,890 --> 00:06:00,989 electric field. So this was the law 156 00:06:00,990 --> 00:06:03,480 and that law of induction, 157 00:06:04,590 --> 00:06:06,929 but also changing electric field 158 00:06:06,930 --> 00:06:09,239 and use magnetic field. 159 00:06:09,240 --> 00:06:11,049 And therefore, these equations allow 160 00:06:11,050 --> 00:06:13,109 after sustaining electromagnetic 161 00:06:13,110 --> 00:06:15,299 waves, to travel 162 00:06:15,300 --> 00:06:16,439 through empty space. 163 00:06:18,780 --> 00:06:21,059 So on a whole, we have those 164 00:06:21,060 --> 00:06:23,039 four equations. 165 00:06:23,040 --> 00:06:24,899 These keep them in mind for a moment. 166 00:06:24,900 --> 00:06:26,779 I would come back to them later. 167 00:06:29,400 --> 00:06:31,889 First, some history, because 168 00:06:31,890 --> 00:06:34,259 it's exactly 150 years 169 00:06:34,260 --> 00:06:35,260 ago that 170 00:06:37,060 --> 00:06:39,899 these equations or Maxwell's paper 171 00:06:39,900 --> 00:06:42,089 dynamical theory of the 172 00:06:42,090 --> 00:06:44,609 electromagnetic field were accepted 173 00:06:44,610 --> 00:06:47,699 for publication by the Royal Society. 174 00:06:47,700 --> 00:06:49,989 But some remarks, what was going 175 00:06:49,990 --> 00:06:52,619 on, unknown about technology 176 00:06:52,620 --> 00:06:53,939 at this time. 177 00:06:53,940 --> 00:06:56,429 So he had the average lifetime 178 00:06:56,430 --> 00:07:00,089 of a light bulb at 1870 179 00:07:00,090 --> 00:07:02,189 was around 10 hours. 180 00:07:02,190 --> 00:07:04,469 The first central station 181 00:07:04,470 --> 00:07:06,389 providing public power is believed to be 182 00:07:06,390 --> 00:07:08,909 one goddamn Surrey 183 00:07:08,910 --> 00:07:10,979 in the UK and it was switched on 184 00:07:10,980 --> 00:07:13,139 in 1881. 185 00:07:13,140 --> 00:07:15,569 So probably Maxwell didn't 186 00:07:15,570 --> 00:07:18,029 get electric light when he Wright 187 00:07:18,030 --> 00:07:19,769 wrote this paper. 188 00:07:21,270 --> 00:07:23,369 There was also a lack of mathematical 189 00:07:23,370 --> 00:07:24,689 fundamentals. 190 00:07:24,690 --> 00:07:27,799 So already Faraday, which 191 00:07:27,800 --> 00:07:30,219 which had which 192 00:07:30,220 --> 00:07:32,549 were who was also researching 193 00:07:32,550 --> 00:07:35,129 a lot in this field, envisioned 194 00:07:35,130 --> 00:07:38,249 in 1830 a mysterious 195 00:07:38,250 --> 00:07:40,499 what he called a mysterious, invisible 196 00:07:40,500 --> 00:07:43,379 electronic state surrounding the magnet, 197 00:07:43,380 --> 00:07:45,719 what we would today call a field 198 00:07:45,720 --> 00:07:46,919 or a vector. 199 00:07:46,920 --> 00:07:49,109 But vector calculus was 200 00:07:49,110 --> 00:07:50,699 not invented yet. 201 00:07:50,700 --> 00:07:52,949 Faraday also hypothesized 202 00:07:52,950 --> 00:07:55,109 that light itself was 203 00:07:55,110 --> 00:07:57,479 a magnetic wave, but shaping 204 00:07:57,480 --> 00:07:59,160 this ideas into like 205 00:08:00,390 --> 00:08:02,459 and a complete theory was way 206 00:08:02,460 --> 00:08:04,660 beyond his mathematical abilities. 207 00:08:06,180 --> 00:08:08,319 So actually, IMEX also didn't 208 00:08:08,320 --> 00:08:10,589 had 20 equations, four 209 00:08:10,590 --> 00:08:13,859 equations, but he had 20 equations. 210 00:08:13,860 --> 00:08:16,049 So you can see some of them here 211 00:08:16,050 --> 00:08:17,050 on the right side. 212 00:08:18,150 --> 00:08:20,070 And it took another 20 years 213 00:08:21,090 --> 00:08:23,309 until they understood by someone 214 00:08:23,310 --> 00:08:25,469 else. And it was 215 00:08:25,470 --> 00:08:27,479 this actually self-taught British 216 00:08:27,480 --> 00:08:30,449 engineer, mathematician and physicist 217 00:08:30,450 --> 00:08:32,609 heavy side who put the 218 00:08:32,610 --> 00:08:34,979 equations then in their present form 219 00:08:34,980 --> 00:08:37,409 like and to this four equations 220 00:08:39,090 --> 00:08:41,399 some years later had 221 00:08:41,400 --> 00:08:43,769 finally had brought the 222 00:08:43,770 --> 00:08:46,949 experimental proof of Maxwell's theory. 223 00:08:46,950 --> 00:08:49,769 He verified that electromagnetic 224 00:08:49,770 --> 00:08:51,959 waves exhibit like light, 225 00:08:51,960 --> 00:08:54,269 like behavior of reflection, 226 00:08:54,270 --> 00:08:57,869 refraction, diffraction and polarization, 227 00:08:57,870 --> 00:09:00,689 and also that the speed of light 228 00:09:00,690 --> 00:09:03,329 and that of electromagnetic radiation 229 00:09:03,330 --> 00:09:05,969 seemed to match up pretty well. 230 00:09:05,970 --> 00:09:08,219 So, um, the proof came up that 231 00:09:08,220 --> 00:09:10,859 light also is an electromagnetic 232 00:09:10,860 --> 00:09:11,860 wave. 233 00:09:13,590 --> 00:09:16,200 So back to Maxwell's equations, 234 00:09:17,400 --> 00:09:19,979 if we come to freespace 235 00:09:19,980 --> 00:09:22,169 propagation in 236 00:09:22,170 --> 00:09:24,809 a vacuum, we have no charges 237 00:09:24,810 --> 00:09:27,209 and we have no currents. 238 00:09:27,210 --> 00:09:29,489 So this role here in 239 00:09:29,490 --> 00:09:31,649 Gulf law, it was zero and 240 00:09:31,650 --> 00:09:33,719 the Ché in an umpire 241 00:09:33,720 --> 00:09:36,869 succored law also equals zero. 242 00:09:36,870 --> 00:09:39,509 So the equation simplified to 243 00:09:39,510 --> 00:09:41,819 this one, which 244 00:09:41,820 --> 00:09:44,460 looks pretty symmetric, 245 00:09:46,380 --> 00:09:48,599 except of here is a minus, 246 00:09:48,600 --> 00:09:51,209 and here are the permeability 247 00:09:51,210 --> 00:09:53,279 in perpetuity, which can 248 00:09:53,280 --> 00:09:55,769 be summed up to the speed of light 249 00:09:55,770 --> 00:09:56,879 here. See? 250 00:10:01,300 --> 00:10:02,300 Um. 251 00:10:04,620 --> 00:10:06,659 When we then want 252 00:10:08,490 --> 00:10:10,739 to come from those equations, 253 00:10:10,740 --> 00:10:12,599 perhaps to something that looks more like 254 00:10:12,600 --> 00:10:14,789 a wave, like we know this waves 255 00:10:14,790 --> 00:10:17,579 are like causing us, 256 00:10:17,580 --> 00:10:19,859 what we do is we take the curl of 257 00:10:19,860 --> 00:10:21,839 the curly questions. 258 00:10:21,840 --> 00:10:24,119 I put those Axworthy 259 00:10:24,120 --> 00:10:26,729 questions here and to the side, 260 00:10:26,730 --> 00:10:28,829 I will show it here for the 261 00:10:28,830 --> 00:10:32,729 love and action for the effect Ifield 262 00:10:32,730 --> 00:10:34,619 Electric Field, for the magnetic field. 263 00:10:34,620 --> 00:10:36,389 It actually works the same. 264 00:10:37,530 --> 00:10:39,929 Um, so we take the koloff, 265 00:10:39,930 --> 00:10:41,100 the current equations. 266 00:10:43,480 --> 00:10:45,729 Here, do 267 00:10:45,730 --> 00:10:47,619 some vector calculus. 268 00:10:47,620 --> 00:10:49,689 So the curl of the 269 00:10:49,690 --> 00:10:52,059 kernel of a vector equals 270 00:10:52,060 --> 00:10:54,339 this one is the gradient of 271 00:10:54,340 --> 00:10:57,189 the divergence of a vector minus 272 00:10:57,190 --> 00:10:59,379 the square gradient of 273 00:10:59,380 --> 00:11:00,380 this vector. 274 00:11:01,660 --> 00:11:03,729 Um, then we come 275 00:11:03,730 --> 00:11:05,110 to this situation here. 276 00:11:06,140 --> 00:11:08,209 Yeah, our divergent we see this 277 00:11:08,210 --> 00:11:10,279 up there equals zero, though, all 278 00:11:10,280 --> 00:11:13,189 this stuff equals zero, 279 00:11:13,190 --> 00:11:15,379 and this 280 00:11:15,380 --> 00:11:18,019 here pretty much 281 00:11:18,020 --> 00:11:20,149 looks like this partya so we 282 00:11:20,150 --> 00:11:21,379 can change this. 283 00:11:21,380 --> 00:11:24,019 Actually, the bema stealing some lines, 284 00:11:24,020 --> 00:11:25,219 I think so. 285 00:11:25,220 --> 00:11:26,899 This is also a division here. 286 00:11:28,970 --> 00:11:31,249 And we end up and 287 00:11:31,250 --> 00:11:33,109 then we put this to the other side and we 288 00:11:33,110 --> 00:11:35,389 end up and those were 289 00:11:35,390 --> 00:11:37,490 called the verifications. 290 00:11:38,510 --> 00:11:40,909 This are still to patcher differential 291 00:11:40,910 --> 00:11:42,199 equations. 292 00:11:42,200 --> 00:11:44,419 And the simple solution of 293 00:11:44,420 --> 00:11:46,579 those equations is a plane 294 00:11:46,580 --> 00:11:48,739 wave, which then you 295 00:11:48,740 --> 00:11:51,469 can see here or 296 00:11:51,470 --> 00:11:53,090 something is happening here. 297 00:11:54,350 --> 00:11:56,629 Yeah. And they are already pretty much 298 00:11:56,630 --> 00:11:58,850 looking like waves like we got 299 00:11:59,990 --> 00:12:02,659 here. Our amplitude here, the 300 00:12:02,660 --> 00:12:04,759 zero, we get a coziness 301 00:12:04,760 --> 00:12:07,369 like the the waveform. 302 00:12:07,370 --> 00:12:09,469 Then we get our omeonga, like the 303 00:12:09,470 --> 00:12:11,629 frequency depending 304 00:12:11,630 --> 00:12:12,739 on the time. 305 00:12:12,740 --> 00:12:15,379 The K here is the vector 306 00:12:15,380 --> 00:12:17,539 and here we get our dependance 307 00:12:17,540 --> 00:12:19,619 on the location and 308 00:12:19,620 --> 00:12:20,620 the face. 309 00:12:22,550 --> 00:12:25,189 This way, if Namak actually represents 310 00:12:25,190 --> 00:12:27,349 the rate of change of the phase and 311 00:12:27,350 --> 00:12:30,199 this also pointing in the direction 312 00:12:30,200 --> 00:12:31,520 of propagation. 313 00:12:34,540 --> 00:12:37,129 A plane wave 314 00:12:37,130 --> 00:12:39,559 can be seen here, for example, 315 00:12:39,560 --> 00:12:41,779 so we get to 316 00:12:41,780 --> 00:12:43,909 you feared and talk on 317 00:12:43,910 --> 00:12:45,999 a magnetic field. 318 00:12:48,170 --> 00:12:50,239 Airplane waves are defined like to have 319 00:12:50,240 --> 00:12:52,519 constant frequency, the way 320 00:12:52,520 --> 00:12:55,159 phones are parallel planes of constant 321 00:12:55,160 --> 00:12:57,289 peak to peak amplitude and 322 00:12:57,290 --> 00:12:59,809 all this normal to the phase velocity 323 00:12:59,810 --> 00:13:02,209 vector and 324 00:13:02,210 --> 00:13:04,429 such a plane wave always 325 00:13:04,430 --> 00:13:06,049 have a pointing vector. 326 00:13:07,320 --> 00:13:09,379 The fear, the pointing 327 00:13:09,380 --> 00:13:12,079 vector represents the energy 328 00:13:12,080 --> 00:13:14,449 flux density of 329 00:13:14,450 --> 00:13:15,450 this wave 330 00:13:17,330 --> 00:13:19,489 and is also 331 00:13:19,490 --> 00:13:21,679 in the direction of propagation, which is 332 00:13:21,680 --> 00:13:24,079 always orthogonal to the to the 333 00:13:24,080 --> 00:13:26,179 to fields, to the E 334 00:13:26,180 --> 00:13:27,480 and the Beefheart. 335 00:13:29,050 --> 00:13:31,279 Um, then every wave has 336 00:13:31,280 --> 00:13:33,109 a polarization. 337 00:13:33,110 --> 00:13:34,879 The polarization has defined us 338 00:13:36,390 --> 00:13:38,589 as the alignment of the 339 00:13:38,590 --> 00:13:40,609 Eastfield, the electric field. 340 00:13:40,610 --> 00:13:42,859 So from here, for example, we have a 341 00:13:42,860 --> 00:13:45,199 horizontal polarization 342 00:13:45,200 --> 00:13:47,779 and we have a linear polarization 343 00:13:47,780 --> 00:13:50,839 here because we have only parts 344 00:13:50,840 --> 00:13:52,759 in one direction. 345 00:13:52,760 --> 00:13:54,169 There are also other forms. 346 00:13:54,170 --> 00:13:56,299 For example, here you can see a 347 00:13:56,300 --> 00:13:59,119 circular polarization. 348 00:13:59,120 --> 00:14:01,369 Um, this occurs when we have two 349 00:14:01,370 --> 00:14:04,009 orthogonality component components 350 00:14:04,010 --> 00:14:06,439 with exactly the same amplitude, 351 00:14:06,440 --> 00:14:08,839 which are 90 degree out of phase. 352 00:14:08,840 --> 00:14:11,029 And those two waves actually then 353 00:14:11,030 --> 00:14:13,489 behave like a wave circling around. 354 00:14:15,500 --> 00:14:17,749 For example, here is an antenna which 355 00:14:17,750 --> 00:14:19,819 can be used to receive a 356 00:14:19,820 --> 00:14:22,789 circular circular 357 00:14:22,790 --> 00:14:24,859 way, if it's called 358 00:14:24,860 --> 00:14:26,959 a QF h. 359 00:14:26,960 --> 00:14:29,929 What they feel are healthy 360 00:14:29,930 --> 00:14:32,179 dial or something like this antenna. 361 00:14:32,180 --> 00:14:34,399 And I did 362 00:14:34,400 --> 00:14:37,429 this one for receiving like some 363 00:14:37,430 --> 00:14:40,189 NOAA weather satellite pictures, 364 00:14:40,190 --> 00:14:42,469 which I sent out in FM. 365 00:14:42,470 --> 00:14:44,539 And it's kind of very 366 00:14:44,540 --> 00:14:47,059 cheap to build this antenna 367 00:14:47,060 --> 00:14:49,309 with some waste, some 368 00:14:49,310 --> 00:14:52,669 waste pipe, some copper cabling. 369 00:14:52,670 --> 00:14:54,769 And the receiving can be done, for 370 00:14:54,770 --> 00:14:56,569 example, with a really cheap software 371 00:14:56,570 --> 00:14:59,119 radio, such an ATSDR. 372 00:15:00,140 --> 00:15:02,389 And with this you can see 373 00:15:02,390 --> 00:15:05,179 Europe kind of from above 374 00:15:05,180 --> 00:15:07,909 can show you one one picture, 375 00:15:07,910 --> 00:15:10,009 which is also not so good 376 00:15:10,010 --> 00:15:11,209 on the bema here. 377 00:15:11,210 --> 00:15:14,119 So this is the ATSDR. 378 00:15:14,120 --> 00:15:16,219 This is the skew 379 00:15:16,220 --> 00:15:18,349 of age, circular, polarized, 380 00:15:18,350 --> 00:15:20,419 polarized antenna and the 381 00:15:20,420 --> 00:15:22,289 countryside here. 382 00:15:22,290 --> 00:15:24,559 You get some open source software 383 00:15:24,560 --> 00:15:25,969 for receiving the signal. 384 00:15:25,970 --> 00:15:28,489 This is the program is called 385 00:15:28,490 --> 00:15:30,049 Geek. You are X, 386 00:15:31,160 --> 00:15:33,919 which is really does nice 387 00:15:33,920 --> 00:15:35,359 FMJ modulation. 388 00:15:35,360 --> 00:15:37,729 And then there is a program to to, 389 00:15:37,730 --> 00:15:39,889 um, to calculate from the 390 00:15:39,890 --> 00:15:42,619 signal the satellite 391 00:15:42,620 --> 00:15:44,359 picture, which. 392 00:15:44,360 --> 00:15:47,209 Yeah, it's just an FM modulated signal. 393 00:15:47,210 --> 00:15:49,489 And here for example, there are 394 00:15:49,490 --> 00:15:51,499 a lot of clouds here. 395 00:15:51,500 --> 00:15:53,599 This is Italy, like the boot of Italy 396 00:15:53,600 --> 00:15:56,299 can be seen here and 397 00:15:56,300 --> 00:15:56,629 yeah. 398 00:15:56,630 --> 00:15:57,630 Here is 399 00:15:59,270 --> 00:16:01,789 what this is the Mediterranean 400 00:16:01,790 --> 00:16:03,919 Reunion with some clouds. 401 00:16:03,920 --> 00:16:06,320 And this is kind of Central Europe. 402 00:16:07,940 --> 00:16:10,249 So we're kind of 20, 403 00:16:10,250 --> 00:16:11,389 25 euros. 404 00:16:11,390 --> 00:16:13,549 You can just see Europe from above. 405 00:16:13,550 --> 00:16:15,979 So if you have some spare time, 406 00:16:15,980 --> 00:16:18,139 you should really go out and 407 00:16:18,140 --> 00:16:19,739 hunt for some satellite. 408 00:16:21,150 --> 00:16:23,869 Um, but back to some 409 00:16:23,870 --> 00:16:25,789 propagation first. 410 00:16:25,790 --> 00:16:27,889 So we get the the vertical and we 411 00:16:27,890 --> 00:16:30,409 got the circular polarization. 412 00:16:30,410 --> 00:16:33,679 Um, there's also elliptical polarization 413 00:16:33,680 --> 00:16:34,910 that comes up. 414 00:16:36,140 --> 00:16:38,149 If you got also two components, like the 415 00:16:38,150 --> 00:16:40,189 circular polarization, but they have 416 00:16:40,190 --> 00:16:42,379 different amplitudes, so we don't 417 00:16:42,380 --> 00:16:43,969 have to circle back to it. 418 00:16:43,970 --> 00:16:46,069 Let's take a 419 00:16:46,070 --> 00:16:48,370 look. I don't know, um, 420 00:16:50,570 --> 00:16:52,639 regarding polarization, if you want 421 00:16:52,640 --> 00:16:54,699 to see, for example, the 422 00:16:54,700 --> 00:16:56,879 horizontal polarized signal with 423 00:16:56,880 --> 00:16:59,419 the vertical polarized antenna, 424 00:16:59,420 --> 00:17:01,519 you always lose 425 00:17:01,520 --> 00:17:02,809 some signal power. 426 00:17:03,830 --> 00:17:06,529 Now, for example, if your circular 427 00:17:06,530 --> 00:17:08,868 antenna is 428 00:17:08,869 --> 00:17:11,179 circling in the wrong direction of 429 00:17:11,180 --> 00:17:12,180 the signal, 430 00:17:13,400 --> 00:17:14,400 um, 431 00:17:15,589 --> 00:17:18,799 it's actually you got something. 432 00:17:18,800 --> 00:17:20,959 It also depends on whether you 433 00:17:20,960 --> 00:17:23,239 are in or out, because every 434 00:17:23,240 --> 00:17:25,879 reflection and the scattering 435 00:17:25,880 --> 00:17:28,249 and stuff also manipulates 436 00:17:28,250 --> 00:17:29,239 your signal. 437 00:17:29,240 --> 00:17:31,759 So you don't only have a vertical 438 00:17:31,760 --> 00:17:34,039 component, but often it makes sense. 439 00:17:34,040 --> 00:17:36,049 Like to move the antenna a bit. 440 00:17:36,050 --> 00:17:38,359 If you have bad signal or in many 441 00:17:38,360 --> 00:17:40,459 modern equipment, you have 442 00:17:40,460 --> 00:17:42,529 like two receiving antenna that do some 443 00:17:42,530 --> 00:17:44,689 kind of receiver diversity to 444 00:17:44,690 --> 00:17:46,859 get both components of a signal. 445 00:17:59,870 --> 00:18:00,870 If we take a look, 446 00:18:02,070 --> 00:18:04,459 unfreeze step is freespace propagation 447 00:18:04,460 --> 00:18:06,559 and the real world, we 448 00:18:06,560 --> 00:18:08,719 assume we have a certain distance 449 00:18:08,720 --> 00:18:10,579 between the transmission antenna and the 450 00:18:10,580 --> 00:18:12,709 receiving antenna, 451 00:18:12,710 --> 00:18:14,599 and it's good to assume that this 452 00:18:14,600 --> 00:18:17,089 distance exceeds 453 00:18:17,090 --> 00:18:19,519 the antenna length and also 454 00:18:19,520 --> 00:18:22,849 the wavelength by several multiples, 455 00:18:22,850 --> 00:18:25,130 because in this case, you can 456 00:18:26,510 --> 00:18:28,789 you can you're 457 00:18:28,790 --> 00:18:30,709 pointing vector like the Earth from 458 00:18:30,710 --> 00:18:33,109 before, um, 459 00:18:34,130 --> 00:18:36,469 seems to radiate from a single 460 00:18:36,470 --> 00:18:37,470 point. 461 00:18:38,210 --> 00:18:40,399 And we can use the phone of 462 00:18:40,400 --> 00:18:42,559 a perfect approximation just 463 00:18:42,560 --> 00:18:44,659 code, which simplifies a 464 00:18:44,660 --> 00:18:47,359 lot because we can divide 465 00:18:47,360 --> 00:18:50,509 our term of propagation, like the point 466 00:18:50,510 --> 00:18:52,879 that the energy flux density 467 00:18:52,880 --> 00:18:55,099 here in a 468 00:18:55,100 --> 00:18:57,409 spherical propagation part. 469 00:18:57,410 --> 00:18:59,509 So you can this can 470 00:18:59,510 --> 00:19:01,039 be seen in the figure here. 471 00:19:02,360 --> 00:19:05,149 We can divide the propagate 472 00:19:05,150 --> 00:19:08,179 the area on a sphere cross. 473 00:19:08,180 --> 00:19:10,279 So here we get a small area and then 474 00:19:10,280 --> 00:19:12,409 we if we move further 475 00:19:12,410 --> 00:19:14,629 away from our transmitting antenna 476 00:19:14,630 --> 00:19:17,509 here in the middle, the area 477 00:19:17,510 --> 00:19:19,609 on this fear grows 478 00:19:19,610 --> 00:19:21,559 proportional to the square of the 479 00:19:21,560 --> 00:19:22,849 distance. 480 00:19:22,850 --> 00:19:24,979 And the same 481 00:19:24,980 --> 00:19:28,069 time, if we use the density, 482 00:19:28,070 --> 00:19:30,440 this one drops inversely proportional. 483 00:19:31,730 --> 00:19:33,709 So this behavior is 484 00:19:34,970 --> 00:19:37,729 the four P.D.A square 485 00:19:37,730 --> 00:19:39,289 and this part. 486 00:19:39,290 --> 00:19:41,599 And then we have the three 487 00:19:41,600 --> 00:19:43,789 dimensional profile coming 488 00:19:43,790 --> 00:19:45,279 from the antenna pattern. 489 00:19:46,600 --> 00:19:49,459 So on the whole, this becomes quite 490 00:19:49,460 --> 00:19:51,339 easy for propagation. 491 00:19:53,660 --> 00:19:55,879 You also know that higher 492 00:19:55,880 --> 00:19:58,039 frequency do not reach as far 493 00:19:58,040 --> 00:20:00,319 as lower frequencies and 494 00:20:00,320 --> 00:20:03,139 this is caused by the antenna 495 00:20:03,140 --> 00:20:04,339 aperture. 496 00:20:04,340 --> 00:20:06,709 The A here 497 00:20:06,710 --> 00:20:08,899 equals the pattern G 498 00:20:08,900 --> 00:20:10,639 are the antenna pattern. 499 00:20:10,640 --> 00:20:12,949 Ah, and here Lundahl 500 00:20:12,950 --> 00:20:15,229 Square, our wavelength 501 00:20:15,230 --> 00:20:17,029 divided by four P. 502 00:20:18,340 --> 00:20:20,529 Um, and the antenna 503 00:20:20,530 --> 00:20:22,929 aperture determines how well an antenna 504 00:20:22,930 --> 00:20:25,449 can pick up power from an incoming 505 00:20:25,450 --> 00:20:27,729 electromagnetic wave and 506 00:20:27,730 --> 00:20:28,990 at higher frequency 507 00:20:30,140 --> 00:20:31,869 can be seen like that. 508 00:20:31,870 --> 00:20:33,969 The antenna in proportion to the 509 00:20:33,970 --> 00:20:36,729 distance is smaller and therefore 510 00:20:36,730 --> 00:20:38,979 we cannot pick up as 511 00:20:38,980 --> 00:20:39,980 much power. 512 00:20:41,230 --> 00:20:43,479 Um, and then, 513 00:20:43,480 --> 00:20:45,889 yeah, we can put in here, 514 00:20:45,890 --> 00:20:46,890 um. 515 00:20:47,710 --> 00:20:50,049 No, that's afterwards, 516 00:20:50,050 --> 00:20:52,179 then at the receiver here, we get the 517 00:20:52,180 --> 00:20:54,609 power PR, this equals 518 00:20:54,610 --> 00:20:56,709 the energy flux density, 519 00:20:56,710 --> 00:20:59,079 which is like the wave in the 520 00:20:59,080 --> 00:21:01,239 in the freespace 521 00:21:02,430 --> 00:21:04,989 multiplied with the antenna aperture. 522 00:21:04,990 --> 00:21:07,329 Then we can put all the stuff here, the S 523 00:21:07,330 --> 00:21:08,560 and the AI 524 00:21:09,700 --> 00:21:11,829 in here, and we got this term 525 00:21:11,830 --> 00:21:14,229 for our receiving power. 526 00:21:16,120 --> 00:21:18,309 At the receiving antenna now 527 00:21:18,310 --> 00:21:21,189 dependent on the distance 528 00:21:21,190 --> 00:21:23,380 and also on the frequency. 529 00:21:26,220 --> 00:21:27,220 And 530 00:21:28,410 --> 00:21:30,509 then we one term, which is 531 00:21:30,510 --> 00:21:32,699 often used as a phrase 532 00:21:32,700 --> 00:21:34,859 transmission equation that defines the 533 00:21:34,860 --> 00:21:37,319 ratio of power available at the input 534 00:21:37,320 --> 00:21:39,479 of the receiving antenna to the 535 00:21:39,480 --> 00:21:41,579 output power to, 536 00:21:41,580 --> 00:21:44,160 um, of the transmitting antenna. 537 00:21:45,430 --> 00:21:47,549 Um, and 538 00:21:47,550 --> 00:21:49,649 here the inverse fact of this 539 00:21:49,650 --> 00:21:51,480 equation is called 540 00:21:52,800 --> 00:21:55,109 the freespace loss, which 541 00:21:55,110 --> 00:21:56,999 is actually the minimum loss you always 542 00:21:57,000 --> 00:21:57,329 have. 543 00:21:57,330 --> 00:22:00,539 If you have two antennas 544 00:22:00,540 --> 00:22:02,669 sending around something, 545 00:22:02,670 --> 00:22:05,639 mostly you get additionally 546 00:22:05,640 --> 00:22:08,339 reflections, diffraction detonations 547 00:22:08,340 --> 00:22:10,169 from the atmosphere and so on. 548 00:22:10,170 --> 00:22:12,419 But, um, yeah, this is 549 00:22:12,420 --> 00:22:14,700 the minimum loss you have. 550 00:22:20,100 --> 00:22:22,409 When it then comes 551 00:22:22,410 --> 00:22:25,229 to Antenna's, um, 552 00:22:25,230 --> 00:22:27,419 we always like this antenna 553 00:22:27,420 --> 00:22:29,549 patterns because they describe like 554 00:22:29,550 --> 00:22:32,189 how much of 555 00:22:32,190 --> 00:22:34,259 the energy is 556 00:22:34,260 --> 00:22:36,899 sent in which direction. 557 00:22:36,900 --> 00:22:39,029 Um, this pattern depends on 558 00:22:39,030 --> 00:22:41,159 the current distribution on the 559 00:22:41,160 --> 00:22:43,319 antenna, because here 560 00:22:43,320 --> 00:22:45,389 we we we have mostly 561 00:22:45,390 --> 00:22:47,909 some metallic materials. 562 00:22:47,910 --> 00:22:49,409 So we get some current. 563 00:22:49,410 --> 00:22:50,520 So J isn't 564 00:22:51,690 --> 00:22:53,129 equal to zero. 565 00:22:53,130 --> 00:22:55,439 For example, here we get a half 566 00:22:55,440 --> 00:22:56,609 Lambda Dipole. 567 00:22:58,560 --> 00:23:00,629 The calculation of the pattern is 568 00:23:00,630 --> 00:23:02,879 then based on Maxwell's 569 00:23:02,880 --> 00:23:04,949 equation. Again, um, 570 00:23:04,950 --> 00:23:07,919 you normally work with a vector potential 571 00:23:07,920 --> 00:23:10,259 and everything in circular 572 00:23:10,260 --> 00:23:12,569 coordinates and it 573 00:23:12,570 --> 00:23:14,489 becomes a bit complicated. 574 00:23:14,490 --> 00:23:16,559 So fortunately there are a lot of 575 00:23:16,560 --> 00:23:18,629 nice programs who do the work 576 00:23:18,630 --> 00:23:19,630 for you. 577 00:23:20,450 --> 00:23:22,799 Um, this year 578 00:23:22,800 --> 00:23:25,049 was calculated with 579 00:23:25,050 --> 00:23:27,329 Fornicator, which is a really 580 00:23:27,330 --> 00:23:28,469 nice program. 581 00:23:28,470 --> 00:23:30,639 It's free and uh, 582 00:23:30,640 --> 00:23:32,430 I think it's not open source, but 583 00:23:33,480 --> 00:23:34,649 it's also for windows. 584 00:23:34,650 --> 00:23:37,019 But it works also fine with Vion 585 00:23:37,020 --> 00:23:38,339 and Linux. 586 00:23:38,340 --> 00:23:40,739 Um, it is based 587 00:23:40,740 --> 00:23:43,109 on the numerical electro 588 00:23:43,110 --> 00:23:45,389 magnetic code which is 589 00:23:45,390 --> 00:23:47,270 the neck here in between. 590 00:23:48,540 --> 00:23:51,119 And the code is based on the 591 00:23:51,120 --> 00:23:53,879 method of moment solution 592 00:23:53,880 --> 00:23:56,489 of the electric field into 593 00:23:56,490 --> 00:23:57,759 equation. 594 00:23:57,760 --> 00:23:58,760 Um, 595 00:24:00,480 --> 00:24:02,609 Nick was originally written for the US 596 00:24:02,610 --> 00:24:04,829 military and is then 597 00:24:04,830 --> 00:24:07,289 put under public domain. 598 00:24:07,290 --> 00:24:10,109 And um, it's a bit complicated 599 00:24:10,110 --> 00:24:12,719 to build your own antennas 600 00:24:12,720 --> 00:24:14,879 with this. So it's possible. 601 00:24:14,880 --> 00:24:16,410 But yeah, probably 602 00:24:17,940 --> 00:24:20,459 there are lots of very expensive program 603 00:24:20,460 --> 00:24:22,859 which makes it easier. 604 00:24:22,860 --> 00:24:24,629 But the cool thing about this program is 605 00:24:24,630 --> 00:24:26,849 that it has many, many example 606 00:24:26,850 --> 00:24:29,069 antennas with which comes 607 00:24:29,070 --> 00:24:31,559 along with the program. 608 00:24:31,560 --> 00:24:33,809 So, for example, also this queue 609 00:24:33,810 --> 00:24:35,939 of antenna I showed before for 610 00:24:35,940 --> 00:24:39,419 receiving the NOAA weather satellites, 611 00:24:39,420 --> 00:24:41,519 um, was also 612 00:24:41,520 --> 00:24:44,489 already included in the examples. 613 00:24:44,490 --> 00:24:46,589 So here you can see the 614 00:24:46,590 --> 00:24:49,649 main window of the program. 615 00:24:49,650 --> 00:24:52,139 Then you can go here to calculate. 616 00:24:52,140 --> 00:24:54,089 Then you get this window here, you can 617 00:24:54,090 --> 00:24:56,999 choose. Yeah, I want to calculate the 618 00:24:57,000 --> 00:24:59,639 pattern of my antenna. 619 00:24:59,640 --> 00:25:01,799 Um, then you can just go to 620 00:25:01,800 --> 00:25:03,959 generate and then 621 00:25:03,960 --> 00:25:06,449 you get a nice you get to 622 00:25:06,450 --> 00:25:08,549 do your patterns but you get also get 623 00:25:08,550 --> 00:25:10,979 a nice Preedy pattern. 624 00:25:10,980 --> 00:25:12,929 For example, here it can be seen this 625 00:25:12,930 --> 00:25:15,239 antenna is for 626 00:25:15,240 --> 00:25:17,489 this weather satellites were running 627 00:25:17,490 --> 00:25:19,799 like above you from Horizon 628 00:25:19,800 --> 00:25:21,059 2000. 629 00:25:21,060 --> 00:25:23,189 So you want to have an antenna pattern 630 00:25:23,190 --> 00:25:25,349 which also goes up from horizontal, 631 00:25:25,350 --> 00:25:27,779 horizontal and which also does 632 00:25:27,780 --> 00:25:29,469 the circular polarization. 633 00:25:29,470 --> 00:25:31,559 So this fits pretty 634 00:25:31,560 --> 00:25:32,560 well. 635 00:25:35,140 --> 00:25:37,389 An important principle 636 00:25:37,390 --> 00:25:39,759 when it comes to antenna patterns 637 00:25:39,760 --> 00:25:42,189 is the interference between 638 00:25:42,190 --> 00:25:43,190 different signals. 639 00:25:44,350 --> 00:25:46,689 So if you get, for example, to 640 00:25:46,690 --> 00:25:49,599 Vegas, you always have a 641 00:25:49,600 --> 00:25:51,639 there's always constructive and 642 00:25:51,640 --> 00:25:54,849 destructive interference. 643 00:25:54,850 --> 00:25:57,309 So, for example, 644 00:25:57,310 --> 00:25:58,989 when it comes to interference here you 645 00:25:58,990 --> 00:26:01,869 can see swimming pool interference 646 00:26:01,870 --> 00:26:03,939 then by I think this is a French 647 00:26:03,940 --> 00:26:06,639 astronaut who is doing this like 648 00:26:06,640 --> 00:26:09,129 putting two arms 649 00:26:09,130 --> 00:26:11,499 in the water and then the waves 650 00:26:11,500 --> 00:26:14,469 coming from two sides are interfering 651 00:26:14,470 --> 00:26:15,399 by each other. 652 00:26:15,400 --> 00:26:17,889 So we got here, we got some peeks of the 653 00:26:17,890 --> 00:26:20,109 of the water. 654 00:26:20,110 --> 00:26:22,299 And sometimes 655 00:26:22,300 --> 00:26:23,300 it goes down 656 00:26:25,900 --> 00:26:28,299 here if we got to where 657 00:26:28,300 --> 00:26:29,799 they are in faith. 658 00:26:29,800 --> 00:26:32,259 So which means 659 00:26:32,260 --> 00:26:34,329 they are starting at 660 00:26:34,330 --> 00:26:37,779 the same time and location, 661 00:26:37,780 --> 00:26:40,299 they are causing constructive 662 00:26:40,300 --> 00:26:42,399 interference, interference. 663 00:26:42,400 --> 00:26:44,619 And if those two 664 00:26:44,620 --> 00:26:45,640 waves are 665 00:26:47,530 --> 00:26:49,719 90 degree order, phase faith 666 00:26:49,720 --> 00:26:50,829 can be seen here. 667 00:26:50,830 --> 00:26:53,739 You get destructive interference. 668 00:26:53,740 --> 00:26:56,049 So if they cancel each other 669 00:26:56,050 --> 00:26:58,269 and for anything in between, 670 00:26:58,270 --> 00:27:00,699 you could also get some some interference 671 00:27:00,700 --> 00:27:02,809 in between, which makes this 672 00:27:02,810 --> 00:27:05,589 resulting signal a bit smaller or better. 673 00:27:05,590 --> 00:27:06,660 Bigger depends. 674 00:27:08,170 --> 00:27:10,839 I also found this nice picture of 675 00:27:10,840 --> 00:27:12,939 two interfering waves 676 00:27:12,940 --> 00:27:15,159 coming from two points here 677 00:27:15,160 --> 00:27:17,259 on Wikipedia so I 678 00:27:17,260 --> 00:27:18,700 can take a deep look. 679 00:27:37,350 --> 00:27:38,609 OK, thanks 680 00:27:41,190 --> 00:27:43,709 very descriptive antenna 681 00:27:43,710 --> 00:27:45,809 for explaining the 682 00:27:45,810 --> 00:27:48,899 interference stuff as the antenna 683 00:27:48,900 --> 00:27:50,579 you can see here, for example, Yagi 684 00:27:50,580 --> 00:27:52,859 antenna built for the 685 00:27:52,860 --> 00:27:55,949 flight from a wireless 686 00:27:55,950 --> 00:27:57,899 network, like to get a directional 687 00:27:57,900 --> 00:28:00,959 antenna for two point fifty four 688 00:28:00,960 --> 00:28:01,960 gigahertz. 689 00:28:03,030 --> 00:28:05,159 You always got a driven element, which 690 00:28:05,160 --> 00:28:07,349 is this one in this case, 691 00:28:07,350 --> 00:28:10,289 and then you get some parasitic 692 00:28:10,290 --> 00:28:13,229 elements, a 693 00:28:13,230 --> 00:28:15,299 director here, another 694 00:28:15,300 --> 00:28:17,459 direction in front 695 00:28:17,460 --> 00:28:19,829 and reflect here in the back. 696 00:28:21,170 --> 00:28:23,309 Um, the parasitic 697 00:28:23,310 --> 00:28:25,589 elements are receiving the signal from 698 00:28:25,590 --> 00:28:27,869 the driven element and at the same time 699 00:28:27,870 --> 00:28:29,310 also sending it out 700 00:28:30,810 --> 00:28:31,859 again. 701 00:28:31,860 --> 00:28:34,259 And they are not exactly resonant, 702 00:28:34,260 --> 00:28:36,599 but somewhat shorter or longer than 703 00:28:36,600 --> 00:28:37,600 are 704 00:28:38,730 --> 00:28:41,849 half lambda wavelength. 705 00:28:41,850 --> 00:28:44,129 And this creates a capacity 706 00:28:44,130 --> 00:28:46,199 for inductive reactants. 707 00:28:46,200 --> 00:28:47,490 And this 708 00:28:48,600 --> 00:28:50,969 reactance modifies the face 709 00:28:50,970 --> 00:28:53,149 of the elements current with respect 710 00:28:53,150 --> 00:28:56,249 to the to its excitation 711 00:28:56,250 --> 00:28:58,319 from the Triveni element. 712 00:28:58,320 --> 00:29:00,749 So you can see this 713 00:29:00,750 --> 00:29:02,459 for this two element. 714 00:29:02,460 --> 00:29:04,679 Yagi, we got the driven element and 715 00:29:04,680 --> 00:29:07,319 the emission from this element 716 00:29:07,320 --> 00:29:09,899 and then we get the director 717 00:29:09,900 --> 00:29:12,539 and the emission from the director 718 00:29:12,540 --> 00:29:14,609 is out of phase in 719 00:29:14,610 --> 00:29:16,679 such a way that here to the front of the 720 00:29:16,680 --> 00:29:19,679 antenna we got a constructive 721 00:29:19,680 --> 00:29:20,879 interference. 722 00:29:20,880 --> 00:29:23,999 So the signals getting getting 723 00:29:24,000 --> 00:29:26,159 bigger and to the 724 00:29:26,160 --> 00:29:28,859 back, the backward emission, 725 00:29:28,860 --> 00:29:31,409 we got a destructive interference 726 00:29:31,410 --> 00:29:33,599 so we get less power 727 00:29:33,600 --> 00:29:35,789 to the back and more power to the front 728 00:29:35,790 --> 00:29:36,790 as wanted. 729 00:29:40,920 --> 00:29:43,289 So what, 730 00:29:43,290 --> 00:29:45,839 for example, if we connect all 731 00:29:45,840 --> 00:29:48,089 this Yagi elements here to 732 00:29:48,090 --> 00:29:50,189 a source and then we could, 733 00:29:50,190 --> 00:29:52,319 for example, manipulate the 734 00:29:52,320 --> 00:29:55,230 face of each element in G individually? 735 00:29:57,630 --> 00:29:59,339 So we can see this here, 736 00:30:00,660 --> 00:30:02,880 this is called manifest right 737 00:30:03,900 --> 00:30:05,909 here, for example, we have a lot of small 738 00:30:05,910 --> 00:30:08,109 antennas, then we have a face 739 00:30:08,110 --> 00:30:10,769 shifter. So it's in German here 740 00:30:10,770 --> 00:30:12,090 on your phones is a German. 741 00:30:13,800 --> 00:30:15,869 And then by 742 00:30:15,870 --> 00:30:18,359 manipulating the face of each antenna, 743 00:30:18,360 --> 00:30:20,669 we can change the direction 744 00:30:20,670 --> 00:30:21,769 of this array. 745 00:30:25,300 --> 00:30:26,300 Um, 746 00:30:28,210 --> 00:30:30,699 the direction of propagation 747 00:30:30,700 --> 00:30:33,369 here is another example, 748 00:30:33,370 --> 00:30:34,959 we got two antennas. 749 00:30:34,960 --> 00:30:37,089 If we put 750 00:30:37,090 --> 00:30:39,069 signals on each antenna with the same 751 00:30:39,070 --> 00:30:41,199 face, the main lobe of 752 00:30:41,200 --> 00:30:43,269 this array, EQUASS, 753 00:30:43,270 --> 00:30:45,939 the main direction of each antenna. 754 00:30:45,940 --> 00:30:48,489 So it's going straight 755 00:30:48,490 --> 00:30:50,109 forward in this direction. 756 00:30:51,400 --> 00:30:53,469 In the other case, 757 00:30:53,470 --> 00:30:55,839 if we delay 758 00:30:55,840 --> 00:30:58,269 the of the face of the antenna 759 00:30:58,270 --> 00:31:00,609 slightly, then 760 00:31:00,610 --> 00:31:02,829 the slope moves up, the lobe 761 00:31:02,830 --> 00:31:05,469 of the antenna array moves up, 762 00:31:05,470 --> 00:31:07,779 and the gain of the resulting 763 00:31:07,780 --> 00:31:09,939 antenna always consists 764 00:31:09,940 --> 00:31:12,429 of the gain from each single antenna. 765 00:31:12,430 --> 00:31:14,769 And then there is an array factor. 766 00:31:15,970 --> 00:31:17,979 So if you have a lot of antenna, you can 767 00:31:17,980 --> 00:31:20,139 create a very 768 00:31:20,140 --> 00:31:21,489 high antenna gains. 769 00:31:21,490 --> 00:31:24,579 And by manipulating the faces, 770 00:31:24,580 --> 00:31:27,699 you can then move the slope direction 771 00:31:27,700 --> 00:31:28,700 as wanted. 772 00:31:32,100 --> 00:31:34,659 There are different techniques to 773 00:31:34,660 --> 00:31:35,829 do the 774 00:31:37,030 --> 00:31:40,059 Festschrift the first one. 775 00:31:40,060 --> 00:31:42,219 Once we're in hardware, so you 776 00:31:42,220 --> 00:31:44,409 get just longer cables, for 777 00:31:44,410 --> 00:31:46,599 example, a car. 778 00:31:46,600 --> 00:31:49,149 Ferdinand Braun invented this technique 779 00:31:49,150 --> 00:31:51,010 in nineteen five. 780 00:31:52,720 --> 00:31:55,089 Then it was mostly used 781 00:31:55,090 --> 00:31:57,339 as often for military 782 00:31:57,340 --> 00:31:58,599 purposes. 783 00:31:58,600 --> 00:32:00,729 For example, it is still highly used in 784 00:32:00,730 --> 00:32:01,930 radar systems. 785 00:32:03,230 --> 00:32:05,529 It was later then also adapted to radio 786 00:32:05,530 --> 00:32:07,719 astronomy, leading also to a Nobel 787 00:32:07,720 --> 00:32:09,849 Prize for physics for 788 00:32:09,850 --> 00:32:13,089 Anthony Hewish and Martin Ryle 789 00:32:13,090 --> 00:32:15,249 for the entire four metric 790 00:32:15,250 --> 00:32:17,179 radio antennas. 791 00:32:17,180 --> 00:32:19,599 Um, but more on this later. 792 00:32:23,250 --> 00:32:25,229 An interesting thing is 793 00:32:26,250 --> 00:32:28,499 when you mix or 794 00:32:28,500 --> 00:32:30,869 like some time ago, a software defined, 795 00:32:30,870 --> 00:32:33,119 defined radio, this technique 796 00:32:33,120 --> 00:32:36,089 came up in a large scale. 797 00:32:36,090 --> 00:32:38,159 And if you mix this with antenna 798 00:32:38,160 --> 00:32:39,959 arrays, you get a really a lot of 799 00:32:39,960 --> 00:32:42,299 flexibility into this 800 00:32:42,300 --> 00:32:44,249 phased arrays. 801 00:32:44,250 --> 00:32:46,319 You can, for example, 802 00:32:46,320 --> 00:32:48,509 manipulate the face of each signal and 803 00:32:48,510 --> 00:32:50,159 software. 804 00:32:50,160 --> 00:32:52,439 You get a very flexible, for example, 805 00:32:52,440 --> 00:32:53,819 beam forming. 806 00:32:53,820 --> 00:32:56,099 Depending on the face you set in 807 00:32:56,100 --> 00:32:57,719 software, you could change the direction 808 00:32:57,720 --> 00:33:00,089 of the beam and also mix 809 00:33:00,090 --> 00:33:02,979 this with Minamo techniques. 810 00:33:02,980 --> 00:33:05,579 So with MIMO multiple input, multiple 811 00:33:05,580 --> 00:33:07,549 output, you additionally do some 812 00:33:07,550 --> 00:33:09,689 recording on each 813 00:33:09,690 --> 00:33:11,819 signal from coming from from 814 00:33:11,820 --> 00:33:13,020 each antenna. 815 00:33:16,170 --> 00:33:18,389 And with this recording, you 816 00:33:18,390 --> 00:33:20,729 try to take advantage of the 817 00:33:20,730 --> 00:33:21,989 channel properties. 818 00:33:21,990 --> 00:33:23,999 For example, in a very scattering 819 00:33:24,000 --> 00:33:26,939 environment, a channel 820 00:33:26,940 --> 00:33:29,819 has a lot of different uncorrelated 821 00:33:29,820 --> 00:33:32,069 paths so it can 822 00:33:32,070 --> 00:33:34,349 increase the data rates, for example, 823 00:33:34,350 --> 00:33:36,839 its use within the new WiFi 824 00:33:36,840 --> 00:33:37,840 standards. 825 00:33:38,940 --> 00:33:40,439 It's also getting cheaper. 826 00:33:40,440 --> 00:33:42,779 So not only 827 00:33:42,780 --> 00:33:45,029 the military's can use it now. 828 00:33:45,030 --> 00:33:46,679 Also, like the mobile app for mobile 829 00:33:46,680 --> 00:33:48,989 broadband, they are doing a lot of 830 00:33:48,990 --> 00:33:50,459 research at the moment. 831 00:33:50,460 --> 00:33:52,619 For example, for a 3D 832 00:33:52,620 --> 00:33:54,209 beam forming. 833 00:33:54,210 --> 00:33:56,459 This is can be seen here in this picture. 834 00:33:56,460 --> 00:33:57,929 So we've got our base station. 835 00:33:57,930 --> 00:34:00,329 Then we get one beam 836 00:34:00,330 --> 00:34:02,399 here down and 837 00:34:02,400 --> 00:34:04,589 several beams to the skyscraper 838 00:34:04,590 --> 00:34:05,219 here. 839 00:34:05,220 --> 00:34:07,380 And the idea is, for example. 840 00:34:09,929 --> 00:34:12,569 To cover different levels of a skyscraper 841 00:34:12,570 --> 00:34:14,249 with different beams on the same 842 00:34:14,250 --> 00:34:16,379 frequency so they are always 843 00:34:16,380 --> 00:34:18,698 afraid to or how 844 00:34:18,699 --> 00:34:21,089 are they shell transport all the data, 845 00:34:21,090 --> 00:34:23,249 those mobile data, so they can 846 00:34:23,250 --> 00:34:25,499 actually reroute frequencies with 847 00:34:25,500 --> 00:34:27,569 this beam forming. 848 00:34:27,570 --> 00:34:30,419 So the latest headline came from 849 00:34:30,420 --> 00:34:32,519 the East China Mobile, which who 850 00:34:32,520 --> 00:34:35,009 did a test with the to the race 851 00:34:35,010 --> 00:34:37,408 with a total of one hundred twenty 852 00:34:37,409 --> 00:34:39,300 twenty eight antennas. 853 00:34:44,300 --> 00:34:46,488 Yes, I already told this 854 00:34:46,489 --> 00:34:48,359 software faced away. 855 00:34:48,360 --> 00:34:50,509 Technology is also 856 00:34:50,510 --> 00:34:52,400 used in radio astronomy 857 00:34:53,690 --> 00:34:56,269 there. It's for receiving 858 00:34:56,270 --> 00:34:58,489 signals and that's 859 00:34:58,490 --> 00:35:00,319 also very general. 860 00:35:00,320 --> 00:35:02,419 An antenna always behaves 861 00:35:02,420 --> 00:35:04,519 the same no matter if you're if it's used 862 00:35:04,520 --> 00:35:06,619 for transmission or reception. 863 00:35:06,620 --> 00:35:07,620 So also, 864 00:35:08,870 --> 00:35:10,969 if you're you know, you need a 865 00:35:10,970 --> 00:35:13,159 really precise time stamp of 866 00:35:13,160 --> 00:35:15,619 each signal on each antenna 867 00:35:15,620 --> 00:35:18,130 and then you can like, um, 868 00:35:19,400 --> 00:35:21,679 process the signal from the different 869 00:35:21,680 --> 00:35:24,139 antennas with different faith 870 00:35:24,140 --> 00:35:25,140 shifts, 871 00:35:26,930 --> 00:35:28,999 depending on which direction 872 00:35:29,000 --> 00:35:31,069 you want to you want 873 00:35:31,070 --> 00:35:33,839 to receive the signals from. 874 00:35:33,840 --> 00:35:35,959 And yeah, you can get a really 875 00:35:35,960 --> 00:35:38,209 good antenna gain by using 876 00:35:38,210 --> 00:35:39,440 a lot of antennas. 877 00:35:41,150 --> 00:35:43,369 And that's also important 878 00:35:44,480 --> 00:35:46,309 to distribute them on. 879 00:35:46,310 --> 00:35:49,249 Along the way, the radio astronomers 880 00:35:49,250 --> 00:35:51,529 actually have the problem 881 00:35:51,530 --> 00:35:53,839 that to explore signals 882 00:35:53,840 --> 00:35:56,119 at lower frequency, 883 00:35:56,120 --> 00:35:58,609 the telescopes need to be really, 884 00:35:58,610 --> 00:36:00,649 really big to have a good resolution. 885 00:36:02,540 --> 00:36:05,689 And it becomes quite handy. 886 00:36:05,690 --> 00:36:07,879 Like if you if you see the, 887 00:36:07,880 --> 00:36:10,339 um, the 888 00:36:10,340 --> 00:36:12,559 dishes, they already 889 00:36:12,560 --> 00:36:14,449 started, like building the dishes and. 890 00:36:14,450 --> 00:36:16,639 Well, yes, but then it becomes quite 891 00:36:16,640 --> 00:36:18,679 handy, like if if they want to get a 892 00:36:18,680 --> 00:36:21,169 signal from another galaxy, which is not 893 00:36:21,170 --> 00:36:23,479 right above the dish, but 894 00:36:23,480 --> 00:36:24,769 at some other location. 895 00:36:24,770 --> 00:36:26,929 So it's just 896 00:36:26,930 --> 00:36:29,000 not possible to move it anymore. 897 00:36:30,270 --> 00:36:32,869 Um, the angular 898 00:36:32,870 --> 00:36:35,479 resolution of a telescope here depends 899 00:36:35,480 --> 00:36:37,849 on the wavelength divided by D. 900 00:36:37,850 --> 00:36:40,519 D and the diameter 901 00:36:40,520 --> 00:36:42,859 of the telescope, or it's 902 00:36:42,860 --> 00:36:43,939 the baseline. 903 00:36:43,940 --> 00:36:46,519 So the length of the maximum 904 00:36:46,520 --> 00:36:48,649 physical separation of the telescope 905 00:36:48,650 --> 00:36:50,059 and the error. 906 00:36:50,060 --> 00:36:52,699 And a nice example is, for example, the 907 00:36:52,700 --> 00:36:55,070 loafer, the low frequency array, 908 00:36:56,150 --> 00:36:58,399 because they want to observe 909 00:36:58,400 --> 00:37:00,529 radio frequencies from 10 910 00:37:00,530 --> 00:37:03,439 to 250 megahertz. 911 00:37:03,440 --> 00:37:05,539 So you got really kind of 912 00:37:05,540 --> 00:37:08,059 long wavelength from thirty 913 00:37:08,060 --> 00:37:10,369 to one point three meter. 914 00:37:12,040 --> 00:37:14,189 So what they do is they build a lot of 915 00:37:14,190 --> 00:37:15,190 different 916 00:37:16,410 --> 00:37:18,629 stations and distribute 917 00:37:18,630 --> 00:37:20,309 them over half Europe 918 00:37:21,850 --> 00:37:24,659 and a total at around 25000 919 00:37:24,660 --> 00:37:26,729 small antennas 920 00:37:26,730 --> 00:37:29,519 concentrated in 48 large 921 00:37:29,520 --> 00:37:30,419 stations. 922 00:37:30,420 --> 00:37:32,069 They are also still building new 923 00:37:32,070 --> 00:37:33,899 stations. I think the last one was 924 00:37:34,980 --> 00:37:37,079 kind of last summer they they 925 00:37:37,080 --> 00:37:39,299 built the latest station in Germany 926 00:37:39,300 --> 00:37:41,669 near Bremen or Bremerhaven, something 927 00:37:41,670 --> 00:37:42,670 like this. 928 00:37:44,670 --> 00:37:48,449 Within Lofa, the angular resolution 929 00:37:48,450 --> 00:37:50,819 goes down to zero point to 930 00:37:50,820 --> 00:37:52,379 one arc seconds. 931 00:37:52,380 --> 00:37:54,599 And the whitespace line is something 932 00:37:54,600 --> 00:37:55,679 like 1000 933 00:37:57,150 --> 00:37:59,309 km and at the highest 934 00:37:59,310 --> 00:38:00,959 frequency. 935 00:38:00,960 --> 00:38:02,099 Mm hmm. 936 00:38:02,100 --> 00:38:04,919 And if you built such stations 937 00:38:06,960 --> 00:38:09,179 in software, it's also built with this 938 00:38:09,180 --> 00:38:10,799 software, radio technology. 939 00:38:10,800 --> 00:38:13,109 Also, the data processing becomes 940 00:38:13,110 --> 00:38:15,539 quite interesting because 941 00:38:15,540 --> 00:38:17,539 perhaps you remember you got your audio 942 00:38:17,540 --> 00:38:19,649 acidy, that 80 minutes of 943 00:38:19,650 --> 00:38:21,599 music, you get around seven hundred 944 00:38:21,600 --> 00:38:23,429 megabytes of that data. 945 00:38:24,630 --> 00:38:27,059 You can hear from 946 00:38:27,060 --> 00:38:29,429 twenty to twenty hertz 947 00:38:29,430 --> 00:38:31,109 to a 20 kilohertz. 948 00:38:31,110 --> 00:38:33,419 So you get like around 20 kilohertz. 949 00:38:33,420 --> 00:38:34,499 Audible bandwidth. 950 00:38:35,700 --> 00:38:38,459 Knackwurst told us 951 00:38:38,460 --> 00:38:40,799 that we need to double something. 952 00:38:40,800 --> 00:38:41,800 Right. 953 00:38:42,780 --> 00:38:45,149 So we often 954 00:38:45,150 --> 00:38:47,849 use the forty four point one kilohertz. 955 00:38:47,850 --> 00:38:50,789 Sixteen bit and two channels. 956 00:38:50,790 --> 00:38:53,429 Um, here we got frequencies 957 00:38:53,430 --> 00:38:55,499 from 10 to 250 958 00:38:55,500 --> 00:38:56,500 megahertz. 959 00:38:57,510 --> 00:38:59,819 Which makes it quite a 960 00:38:59,820 --> 00:39:02,009 bigger bandwidth and 961 00:39:02,010 --> 00:39:04,139 we get that like 25000 962 00:39:04,140 --> 00:39:06,659 antennas, which all 963 00:39:06,660 --> 00:39:08,759 generate a 964 00:39:08,760 --> 00:39:10,919 lot of data, what they then 965 00:39:10,920 --> 00:39:13,079 do is they do a kind of pre 966 00:39:13,080 --> 00:39:15,389 processing of the data to station 967 00:39:15,390 --> 00:39:18,029 already, like they have to decide 968 00:39:18,030 --> 00:39:20,389 before which direction they want to 969 00:39:20,390 --> 00:39:22,409 go to get the signals from. 970 00:39:22,410 --> 00:39:24,509 And then they do this correlation of 971 00:39:24,510 --> 00:39:27,809 the signals already partly 972 00:39:27,810 --> 00:39:30,209 at each station, and then they 973 00:39:30,210 --> 00:39:32,699 send the data to 974 00:39:32,700 --> 00:39:34,650 the Netherlands, to Corning and 975 00:39:35,700 --> 00:39:37,829 wear blue gene supercomputer. 976 00:39:37,830 --> 00:39:39,959 Does the final processing from the 977 00:39:39,960 --> 00:39:42,239 distant stations then? 978 00:39:50,640 --> 00:39:53,309 Um, this Lofa telescope 979 00:39:53,310 --> 00:39:55,649 is also a Pathfinder project for 980 00:39:55,650 --> 00:39:57,530 the square kilometer array. 981 00:39:58,680 --> 00:40:00,809 And this one is 982 00:40:00,810 --> 00:40:02,999 in preconstruction phase 983 00:40:03,000 --> 00:40:04,000 at the moment. 984 00:40:05,760 --> 00:40:08,189 The and 985 00:40:08,190 --> 00:40:10,559 it's planned to be built in Australia 986 00:40:10,560 --> 00:40:12,780 apart in another part in South Africa. 987 00:40:13,830 --> 00:40:16,319 The plan is to cover frequency range 988 00:40:16,320 --> 00:40:18,449 from 50 megahertz up to 989 00:40:18,450 --> 00:40:20,579 14 gigahertz 990 00:40:20,580 --> 00:40:22,409 in the first two phases of the 991 00:40:22,410 --> 00:40:23,410 construction. 992 00:40:24,720 --> 00:40:27,149 So here you can see 993 00:40:27,150 --> 00:40:28,389 an animation. 994 00:40:28,390 --> 00:40:30,629 It's not very big of 995 00:40:30,630 --> 00:40:31,889 the dish antennas. 996 00:40:33,120 --> 00:40:35,669 And Phase one shall provide 997 00:40:35,670 --> 00:40:38,099 10 percent of the total 998 00:40:38,100 --> 00:40:41,009 collecting area at low frequencies 999 00:40:41,010 --> 00:40:43,199 by 2020, 1000 00:40:43,200 --> 00:40:45,419 20 by 2020, 1001 00:40:45,420 --> 00:40:47,789 and phase two, then share 1002 00:40:47,790 --> 00:40:50,129 complete the full array at lower 1003 00:40:50,130 --> 00:40:53,039 frequencies by 2025 1004 00:40:53,040 --> 00:40:55,229 and then phase three shall go 1005 00:40:55,230 --> 00:40:57,030 up to 30 gigahertz. 1006 00:40:58,110 --> 00:41:00,509 It's actually at three telescopes because 1007 00:41:00,510 --> 00:41:02,919 of the of the huge bandwidth. 1008 00:41:02,920 --> 00:41:04,219 So two dishes. 1009 00:41:04,220 --> 00:41:06,359 You can see the animation of 1010 00:41:06,360 --> 00:41:09,209 one of the dish antenna arrays. 1011 00:41:09,210 --> 00:41:11,279 And for the low frequency 1012 00:41:11,280 --> 00:41:14,099 is you get an array of dipoles. 1013 00:41:15,910 --> 00:41:18,129 The maximum line of this 1014 00:41:18,130 --> 00:41:21,459 antenna are three thousand kilometers 1015 00:41:21,460 --> 00:41:23,619 and the collecting area is one square 1016 00:41:23,620 --> 00:41:25,389 kilometer. Therefore, it's called square 1017 00:41:25,390 --> 00:41:26,390 kilometer array. 1018 00:41:28,180 --> 00:41:30,399 And within this project, also the main 1019 00:41:30,400 --> 00:41:32,649 challenge is the huge 1020 00:41:32,650 --> 00:41:34,499 amount of data. 1021 00:41:34,500 --> 00:41:36,909 I had an interview with the technical 1022 00:41:36,910 --> 00:41:39,159 director of the CIA earlier 1023 00:41:39,160 --> 00:41:41,229 this year, and he told that they 1024 00:41:41,230 --> 00:41:43,149 are they are 1025 00:41:45,130 --> 00:41:47,139 planning to have more data than the 1026 00:41:47,140 --> 00:41:49,029 Internet carries today on are all 1027 00:41:49,030 --> 00:41:50,590 together on their stations. 1028 00:41:51,880 --> 00:41:53,799 And all this data has to be processed, 1029 00:41:53,800 --> 00:41:55,899 transported and made available for 1030 00:41:55,900 --> 00:41:57,909 the scientists. 1031 00:41:57,910 --> 00:42:00,159 They plan to deploy like fiber 1032 00:42:00,160 --> 00:42:02,289 optic with the length that would reach 1033 00:42:02,290 --> 00:42:04,239 around the world twice. 1034 00:42:04,240 --> 00:42:06,429 And they actually trust in Moore's 1035 00:42:06,430 --> 00:42:08,829 Law to process all the data, although 1036 00:42:08,830 --> 00:42:11,079 they wait until they buy 1037 00:42:11,080 --> 00:42:13,539 the hardware until, yeah, 1038 00:42:13,540 --> 00:42:15,849 later is really 1039 00:42:15,850 --> 00:42:16,850 needed. 1040 00:42:17,770 --> 00:42:20,289 Um, the scientific 1041 00:42:20,290 --> 00:42:22,689 goals of this 1042 00:42:22,690 --> 00:42:24,969 this array, 1043 00:42:24,970 --> 00:42:27,279 this telescope is 1044 00:42:27,280 --> 00:42:28,299 between others. 1045 00:42:28,300 --> 00:42:30,759 The twenty one centimeter hydrogen 1046 00:42:30,760 --> 00:42:32,859 line, that channel map, 1047 00:42:32,860 --> 00:42:35,089 a billion galaxy out 1048 00:42:35,090 --> 00:42:37,539 to the edge of the observable 1049 00:42:37,540 --> 00:42:38,749 universe. 1050 00:42:38,750 --> 00:42:40,809 They will do research and the process 1051 00:42:40,810 --> 00:42:43,419 that's resulting in the galaxy formation 1052 00:42:43,420 --> 00:42:45,280 and evolution will be done 1053 00:42:46,600 --> 00:42:49,179 and research and the evolution of cosmic 1054 00:42:49,180 --> 00:42:51,639 magnetic fields and 1055 00:42:51,640 --> 00:42:53,739 the epoch of ionized 1056 00:42:53,740 --> 00:42:56,559 ionization after the Big Bang. 1057 00:42:56,560 --> 00:42:58,809 But yeah, here all this 1058 00:42:58,810 --> 00:43:00,879 stuff is again connected somehow 1059 00:43:00,880 --> 00:43:02,949 to relativity creation of 1060 00:43:02,950 --> 00:43:04,239 the universe. 1061 00:43:04,240 --> 00:43:06,639 So I will end here. 1062 00:43:06,640 --> 00:43:07,960 Thanks for your attention. 1063 00:43:09,730 --> 00:43:12,039 Yeah. And if you have some questions, I 1064 00:43:12,040 --> 00:43:14,199 can try to answer them. 1065 00:43:14,200 --> 00:43:15,200 OK. 1066 00:43:22,810 --> 00:43:25,189 As always, there's four microphones, 1067 00:43:25,190 --> 00:43:27,139 one day, one day, one day, one day, just 1068 00:43:27,140 --> 00:43:27,649 line up. 1069 00:43:27,650 --> 00:43:29,779 If you have any questions, 1070 00:43:29,780 --> 00:43:31,609 maybe you need a little refreshment and a 1071 00:43:31,610 --> 00:43:33,049 vector calculus. 1072 00:43:33,050 --> 00:43:35,329 Maybe just want to know some physics. 1073 00:43:35,330 --> 00:43:36,330 Just ask, 1074 00:43:37,970 --> 00:43:39,889 do we have questions from the Internet 1075 00:43:41,810 --> 00:43:44,539 on Internets already asleep. 1076 00:43:44,540 --> 00:43:46,429 OK, go ahead. 1077 00:43:46,430 --> 00:43:48,709 When when you were getting the 1078 00:43:48,710 --> 00:43:50,749 images from the satellites, could you 1079 00:43:50,750 --> 00:43:52,909 rely on good documentation or 1080 00:43:52,910 --> 00:43:54,380 was it a lot of trial and error? 1081 00:43:55,940 --> 00:43:58,129 No, there's actually kind 1082 00:43:58,130 --> 00:44:00,259 of good documentation and the 1083 00:44:00,260 --> 00:44:01,260 Internet. 1084 00:44:02,810 --> 00:44:04,969 Yeah, just 1085 00:44:04,970 --> 00:44:07,759 search around for no satellites 1086 00:44:07,760 --> 00:44:09,469 and FDR. 1087 00:44:09,470 --> 00:44:12,019 I also wrote an article about this 1088 00:44:12,020 --> 00:44:14,089 and the hardware projects, but it's not 1089 00:44:14,090 --> 00:44:15,389 online, unfortunately. 1090 00:44:15,390 --> 00:44:17,669 So you do have to buy 1091 00:44:17,670 --> 00:44:18,919 the magazine. 1092 00:44:18,920 --> 00:44:19,920 Thank you. Thanks. 1093 00:44:21,000 --> 00:44:22,000 OK, 1094 00:44:24,910 --> 00:44:28,519 that's a software you presented. 1095 00:44:28,520 --> 00:44:30,649 Consider cases of 1096 00:44:30,650 --> 00:44:32,569 non free propagation. 1097 00:44:32,570 --> 00:44:35,149 So if an 1098 00:44:35,150 --> 00:44:37,399 electromagnetic active medium 1099 00:44:37,400 --> 00:44:39,170 is present in the near field. 1100 00:44:40,930 --> 00:44:42,670 This antenna software, 1101 00:44:44,680 --> 00:44:47,409 I don't think so, actually, 1102 00:44:47,410 --> 00:44:49,719 you can you can do like 1103 00:44:49,720 --> 00:44:51,969 areas like 1104 00:44:51,970 --> 00:44:53,380 Watson name. 1105 00:44:55,990 --> 00:44:58,449 Fletching and in German, 1106 00:44:58,450 --> 00:45:00,669 um, but 1107 00:45:00,670 --> 00:45:03,039 I think that Dawn doesn't 1108 00:45:03,040 --> 00:45:06,219 support, like, different materials 1109 00:45:06,220 --> 00:45:08,319 of the surrounding space, but 1110 00:45:08,320 --> 00:45:09,309 I'm not quite sure. 1111 00:45:09,310 --> 00:45:12,069 So there's also a lot of documentation 1112 00:45:12,070 --> 00:45:14,379 on the website from Phonic 1113 00:45:14,380 --> 00:45:16,510 to perhaps better have a look there. 1114 00:45:17,890 --> 00:45:19,299 Thank you. 1115 00:45:19,300 --> 00:45:20,139 OK. 1116 00:45:20,140 --> 00:45:22,569 To the right place in the 1117 00:45:22,570 --> 00:45:25,569 plot with a Yagi antenna, 1118 00:45:25,570 --> 00:45:27,999 the amplified amplitude of the 1119 00:45:28,000 --> 00:45:30,009 passive element was higher than the 1120 00:45:30,010 --> 00:45:32,669 field, uh, field 1121 00:45:32,670 --> 00:45:34,509 of the amplitude, often driven element. 1122 00:45:34,510 --> 00:45:36,399 I wonder how that could be if a 1123 00:45:36,400 --> 00:45:38,799 metrically producing some energy 1124 00:45:38,800 --> 00:45:41,099 or whether this big field 1125 00:45:41,100 --> 00:45:44,019 size come from on that plot. 1126 00:45:44,020 --> 00:45:46,689 Yeah. Um, from Wikipedia. 1127 00:45:48,010 --> 00:45:50,499 No, actually it shall be smaller 1128 00:45:50,500 --> 00:45:51,279 because yeah. 1129 00:45:51,280 --> 00:45:53,949 You always have some, some losses 1130 00:45:53,950 --> 00:45:56,139 when you're when, when the 1131 00:45:56,140 --> 00:45:58,809 elementary CFED and then again sent 1132 00:45:58,810 --> 00:45:59,949 the stuff. 1133 00:45:59,950 --> 00:46:00,939 So yeah. 1134 00:46:00,940 --> 00:46:01,940 You're right. 1135 00:46:03,850 --> 00:46:06,019 OK, yes. 1136 00:46:06,020 --> 00:46:06,939 Uh yes. 1137 00:46:06,940 --> 00:46:08,709 How do you deal with a noise being 1138 00:46:08,710 --> 00:46:10,329 generated by the antenna itself. 1139 00:46:12,100 --> 00:46:14,469 Can you do the waterways quickly 1140 00:46:14,470 --> 00:46:17,259 lowered the noise of content itself or 1141 00:46:17,260 --> 00:46:19,840 ways of making sure you have the maximum 1142 00:46:21,730 --> 00:46:22,730 noise ratio? 1143 00:46:24,050 --> 00:46:26,439 Um, you mean in a phased 1144 00:46:26,440 --> 00:46:28,719 array on the Yagi, 1145 00:46:28,720 --> 00:46:30,309 for example, or with, uh, with with 1146 00:46:30,310 --> 00:46:32,559 additions like, uh, you 1147 00:46:32,560 --> 00:46:34,389 in the later square kilometer array? 1148 00:46:35,620 --> 00:46:37,479 Oh, I don't know, actually. 1149 00:46:38,910 --> 00:46:41,429 And not so much into 1150 00:46:41,430 --> 00:46:43,529 the technology, I think 1151 00:46:43,530 --> 00:46:45,299 they have to deal with it because 1152 00:46:45,300 --> 00:46:47,459 probably they will catch up a lot of 1153 00:46:47,460 --> 00:46:50,519 noise, but yeah, probably, 1154 00:46:50,520 --> 00:46:52,799 you know, often lack of noise 1155 00:46:52,800 --> 00:46:54,809 have some regularity. 1156 00:46:54,810 --> 00:46:57,089 So you collect a 1157 00:46:57,090 --> 00:46:59,189 large amount of signals and then you can 1158 00:46:59,190 --> 00:47:01,170 kind of calculate the noise out. 1159 00:47:02,680 --> 00:47:04,749 So that's how you normally do it and 1160 00:47:04,750 --> 00:47:07,599 yeah, OK, Internet, 1161 00:47:09,970 --> 00:47:12,669 we have two questions here. 1162 00:47:12,670 --> 00:47:14,889 One is it is 1163 00:47:14,890 --> 00:47:17,019 intercontinental assessed to 1164 00:47:17,020 --> 00:47:17,979 be possible. 1165 00:47:17,980 --> 00:47:20,259 And if yes, which 1166 00:47:20,260 --> 00:47:22,959 type of antennas would they 1167 00:47:22,960 --> 00:47:24,549 need to do this? 1168 00:47:24,550 --> 00:47:27,429 And how big facilities, antennas be 1169 00:47:27,430 --> 00:47:28,569 intercontinental. 1170 00:47:28,570 --> 00:47:30,729 What is those given to 1171 00:47:30,730 --> 00:47:31,940 you? Yes. 1172 00:47:33,440 --> 00:47:35,119 Slow skating? 1173 00:47:35,120 --> 00:47:37,259 Yes, someone said, 1174 00:47:37,260 --> 00:47:39,559 yes, it's quite 1175 00:47:39,560 --> 00:47:40,560 slow. 1176 00:47:41,390 --> 00:47:43,669 OK. I actually 1177 00:47:43,670 --> 00:47:46,249 don't know what slow scale 1178 00:47:46,250 --> 00:47:47,509 TV is. 1179 00:47:47,510 --> 00:47:50,059 No, as far as 1180 00:47:50,060 --> 00:47:51,710 mass TV is possible 1181 00:47:52,940 --> 00:47:54,469 and H.F. 1182 00:47:54,470 --> 00:47:56,690 so as a TV is possible, 1183 00:47:57,710 --> 00:48:00,139 but you need time 1184 00:48:00,140 --> 00:48:01,809 because it's extremely slow, because of 1185 00:48:01,810 --> 00:48:02,959 low frequencies. 1186 00:48:02,960 --> 00:48:05,359 So you use this ionosphere 1187 00:48:05,360 --> 00:48:07,549 stuff reflecting stuff at 1188 00:48:07,550 --> 00:48:09,619 high frequencies. Yeah, well 1189 00:48:09,620 --> 00:48:11,089 OK. 1190 00:48:11,090 --> 00:48:13,249 On 20 meters the right 1191 00:48:13,250 --> 00:48:14,250 place. 1192 00:48:15,350 --> 00:48:16,820 Maybe I missed something, but 1193 00:48:17,870 --> 00:48:20,239 what is the connection between all this 1194 00:48:20,240 --> 00:48:22,489 Maxwell's stuff and the face area 1195 00:48:22,490 --> 00:48:23,509 stuff? 1196 00:48:23,510 --> 00:48:25,549 Because it does face array you can use 1197 00:48:25,550 --> 00:48:28,489 with conventional 1198 00:48:28,490 --> 00:48:30,619 ways to like ultrasonic or something. 1199 00:48:31,660 --> 00:48:34,399 Where's the connection between is this 1200 00:48:34,400 --> 00:48:36,979 really used for the space array? 1201 00:48:36,980 --> 00:48:39,919 This is only a superposition of 1202 00:48:39,920 --> 00:48:41,449 elementary waves. 1203 00:48:41,450 --> 00:48:42,529 Yeah, the farfield. 1204 00:48:42,530 --> 00:48:44,809 So I don't see the connection 1205 00:48:44,810 --> 00:48:46,789 to the equations there. 1206 00:48:46,790 --> 00:48:49,609 So the mics were equations like explain 1207 00:48:49,610 --> 00:48:51,589 or wave propagation. 1208 00:48:51,590 --> 00:48:53,689 So it doesn't matter if you have 1209 00:48:53,690 --> 00:48:55,819 radio frequencies or light. 1210 00:48:55,820 --> 00:48:58,639 So they are kind of explaining 1211 00:48:58,640 --> 00:49:00,139 the wave propagation. 1212 00:49:00,140 --> 00:49:02,329 And then I try 1213 00:49:02,330 --> 00:49:04,879 to explain what you can do with 1214 00:49:04,880 --> 00:49:07,189 a different field of the wave 1215 00:49:07,190 --> 00:49:08,029 propagation. 1216 00:49:08,030 --> 00:49:09,650 And regarding two antennas, 1217 00:49:10,700 --> 00:49:13,189 but the this 1218 00:49:13,190 --> 00:49:15,799 what you used afterwards, it's not 1219 00:49:15,800 --> 00:49:16,969 not a prop. 1220 00:49:16,970 --> 00:49:18,889 or it doesn't use a prop. 1221 00:49:18,890 --> 00:49:21,559 or a unique property of 1222 00:49:21,560 --> 00:49:23,809 radio frequencies for 1223 00:49:23,810 --> 00:49:25,869 this beam forming stuff. 1224 00:49:25,870 --> 00:49:27,829 So this is a fear that 1225 00:49:29,240 --> 00:49:30,799 with all your waves, for example. 1226 00:49:30,800 --> 00:49:31,909 Yeah, that's right. 1227 00:49:31,910 --> 00:49:32,910 So, OK. 1228 00:49:34,820 --> 00:49:35,820 OK, 1229 00:49:38,370 --> 00:49:40,339 John, what do you I will always be the 1230 00:49:40,340 --> 00:49:42,409 case that I would need multiple receivers 1231 00:49:42,410 --> 00:49:44,749 to make any use of a receiving 1232 00:49:44,750 --> 00:49:47,269 array or 1233 00:49:47,270 --> 00:49:49,849 be any way to use just one receiver 1234 00:49:51,020 --> 00:49:52,700 with an array 1235 00:49:54,260 --> 00:49:56,839 and somehow calculate 1236 00:49:56,840 --> 00:49:57,840 the direction. 1237 00:49:59,950 --> 00:50:02,049 So just if you just use 1238 00:50:02,050 --> 00:50:04,099 one receiver off the antenna 1239 00:50:05,260 --> 00:50:08,469 and to do what to 1240 00:50:08,470 --> 00:50:10,719 I don't know if you want like a 1241 00:50:10,720 --> 00:50:12,669 directional reception or something like 1242 00:50:12,670 --> 00:50:15,039 that, it 1243 00:50:15,040 --> 00:50:17,259 is always the case that I need one 1244 00:50:17,260 --> 00:50:19,509 receiver for one part 1245 00:50:19,510 --> 00:50:20,510 of the antenna. 1246 00:50:21,940 --> 00:50:24,369 They you need some kind of 1247 00:50:24,370 --> 00:50:26,679 construction that does the dove 1248 00:50:26,680 --> 00:50:28,749 activity, so you don't 1249 00:50:28,750 --> 00:50:29,859 need an antenna. 1250 00:50:29,860 --> 00:50:32,049 There are also other forms of 1251 00:50:32,050 --> 00:50:34,329 antennas which are directional, 1252 00:50:34,330 --> 00:50:36,549 but within the area, like you need 1253 00:50:36,550 --> 00:50:39,009 different signals to get 1254 00:50:39,010 --> 00:50:41,259 this different faces like to to 1255 00:50:41,260 --> 00:50:43,539 create your dove activity 1256 00:50:43,540 --> 00:50:44,540 then. 1257 00:50:50,370 --> 00:50:52,289 Please go to the mic if you want to say 1258 00:50:52,290 --> 00:50:54,719 something so extreme, can cannot 1259 00:50:54,720 --> 00:50:55,720 understand you. 1260 00:50:56,640 --> 00:50:58,939 Well, for a case of a race, 1261 00:50:58,940 --> 00:51:01,499 you don't need several receivers 1262 00:51:01,500 --> 00:51:03,459 at every antenna part. 1263 00:51:03,460 --> 00:51:05,659 You can also combine to signal. 1264 00:51:05,660 --> 00:51:07,229 And HeartWare was the face shifters, like 1265 00:51:07,230 --> 00:51:09,359 she said. And after 1266 00:51:09,360 --> 00:51:11,069 you have combined to signal over some 1267 00:51:11,070 --> 00:51:13,259 power components, you can just put 1268 00:51:13,260 --> 00:51:15,389 it into one single 1269 00:51:15,390 --> 00:51:17,489 receiver. But you have to 1270 00:51:17,490 --> 00:51:19,889 do all those fancy face shifting 1271 00:51:19,890 --> 00:51:22,049 stuff in hardware and that's how it is. 1272 00:51:22,050 --> 00:51:24,119 And to combine the signals after 1273 00:51:24,120 --> 00:51:25,120 you have digitalize. 1274 00:51:27,160 --> 00:51:28,160 Thank you. 1275 00:51:28,650 --> 00:51:30,049 OK, thank you. 1276 00:51:30,050 --> 00:51:32,089 Any more questions, OK? 1277 00:51:32,090 --> 00:51:33,649 Internet? 1278 00:51:33,650 --> 00:51:35,829 Yeah, I have one question about 1279 00:51:35,830 --> 00:51:37,969 some excellent questions. 1280 00:51:37,970 --> 00:51:40,129 And this question is, 1281 00:51:40,130 --> 00:51:42,939 is a second secret men's 1282 00:51:42,940 --> 00:51:45,409 statement on a specific points 1283 00:51:45,410 --> 00:51:46,909 or officer who fired? 1284 00:51:49,240 --> 00:51:51,550 And what on a specific path, 1285 00:51:52,720 --> 00:51:55,059 on a specific point or 1286 00:51:55,060 --> 00:51:56,289 so, who will filed? 1287 00:51:57,430 --> 00:51:59,439 You mean field the field? 1288 00:51:59,440 --> 00:52:02,199 Yes, um, 1289 00:52:02,200 --> 00:52:04,449 you know, it's it 1290 00:52:04,450 --> 00:52:05,959 doesn't need to be a point. 1291 00:52:05,960 --> 00:52:08,049 So, for example, but also if you got 1292 00:52:08,050 --> 00:52:10,779 capacitors, you can have 1293 00:52:10,780 --> 00:52:13,509 rectangular or whatever 1294 00:52:13,510 --> 00:52:15,879 form of 1295 00:52:15,880 --> 00:52:16,880 um. 1296 00:52:18,070 --> 00:52:19,749 I know this was the first one. 1297 00:52:19,750 --> 00:52:20,750 What the second. 1298 00:52:21,890 --> 00:52:23,839 Maybe just show the slide so we know what 1299 00:52:23,840 --> 00:52:24,840 you're talking about. 1300 00:52:26,540 --> 00:52:27,540 So. 1301 00:52:34,470 --> 00:52:35,470 So. 1302 00:52:40,370 --> 00:52:42,349 It was the second equation, right? 1303 00:52:43,620 --> 00:52:44,620 Yes, 1304 00:52:46,130 --> 00:52:48,619 and then if it's one point 1305 00:52:48,620 --> 00:52:51,259 or if it could be a kid, 1306 00:52:51,260 --> 00:52:53,359 if if this equation 1307 00:52:53,360 --> 00:52:55,819 is meant as a statement on a specific 1308 00:52:55,820 --> 00:52:58,040 point or who field. 1309 00:53:01,160 --> 00:53:03,259 Sorry, I don't get to stand on 1310 00:53:03,260 --> 00:53:05,479 the entire field because 1311 00:53:05,480 --> 00:53:07,939 the magnetic field, not 1312 00:53:07,940 --> 00:53:10,759 a magnetic point, which does not exist. 1313 00:53:10,760 --> 00:53:11,760 Um. 1314 00:53:13,040 --> 00:53:14,040 Thank you. 1315 00:53:15,170 --> 00:53:16,789 Technically, this is a statement about 1316 00:53:16,790 --> 00:53:19,249 the sources of the magnetic field, so 1317 00:53:19,250 --> 00:53:21,499 the second makes the equation just 1318 00:53:21,500 --> 00:53:23,119 says that there are no sources for the 1319 00:53:23,120 --> 00:53:25,129 magnetic field, which basically means 1320 00:53:25,130 --> 00:53:26,420 there are no monopoles. 1321 00:53:28,820 --> 00:53:30,350 Do we have more questions? 1322 00:53:36,140 --> 00:53:38,449 OK, thank you, thank us, speaker, 1323 00:53:38,450 --> 00:53:39,450 again, please.