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#1
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The nature of Free Space (Once called, "The Lumeniferous Aether")
"rickman" wrote in message
... Uh, if they are matched, there won't be any reflection energy. Untrue, because you match the inout impedance but not the radiation resistance, which in the case of a dipole are largely the same, so, yes, in a dipole it does all get radiated. |
#2
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The nature of Free Space (Once called, "The Lumeniferous Aether")
On 9/12/2015 5:33 PM, Brian Morrison wrote:
On Sat, 12 Sep 2015 22:17:27 +0100 "gareth" wrote: "rickman" wrote in message ... Uh, if they are matched, there won't be any reflection energy. Untrue, because you match the inout impedance but not the radiation resistance, which in the case of a dipole are largely the same, so, yes, in a dipole it does all get radiated. If it doesn't get radiated with a matched antenna that has a small radiation resistance then that remaining energy is converted into heat in the antenna/matching network, not reflected back to the Tx. Picture that with ideal components and then tell me what happens. Or better yet, since we are talking about antenna geometry and not feed lines and matching networks, imagine *no* feed line, just a signal generator with a dipole attached directly to the output. The output impedance of the generator exactly matches the input impedance of the antenna in each case. The power measured going into the antenna in each case is 100 W. Will the emitted field be the same? -- Rick |
#3
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The nature of Free Space (Once called, "The Lumeniferous Aether")
"rickman" wrote in message ... On 9/12/2015 5:33 PM, Brian Morrison wrote: On Sat, 12 Sep 2015 22:17:27 +0100 "gareth" wrote: "rickman" wrote in message ... Uh, if they are matched, there won't be any reflection energy. Untrue, because you match the inout impedance but not the radiation resistance, which in the case of a dipole are largely the same, so, yes, in a dipole it does all get radiated. If it doesn't get radiated with a matched antenna that has a small radiation resistance then that remaining energy is converted into heat in the antenna/matching network, not reflected back to the Tx. # Picture that with ideal components and then tell me what happens. Or # better yet, since we are talking about antenna geometry and not feed # lines and matching networks, imagine *no* feed line, just a signal # generator with a dipole attached directly to the output. The output # impedance of the generator exactly matches the input impedance of the # antenna in each case. The power measured going into the antenna in each # case is 100 W. Will the emitted field be the same? I'm with you. For a valid comparison of the radiation of two antennas, they both have to have the same power radiated to start with. If one has power reflected/consumed by heat or whatever, then simply crank up the power for that antenna until they both radiate the same power. Let's consider an isotropic antenna (that's about the limit of "shortness") compared with whatever bigger antenna. At distance D, the isotropic antenna will have all its power spread over a spherical surface of radius D. As I understand Gareth's assertion, at every position on the point source sphere, the field strength would be lower than for a bigger antenna replacing the point source. I doubt that is true. |
#4
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The nature of Free Space (Once called, "The Lumeniferous Aether")
On Saturday, September 12, 2015 at 6:52:44 PM UTC-5, Wayne wrote:
As I understand Gareth's assertion, at every position on the point source sphere, the field strength would be lower than for a bigger antenna replacing the point source. I doubt that is true. He's trying to blame the poor old radiator, "free space", or the "Aether" for rig to feed line to radiator matching losses. My reason to even join this circus is to bring to his attention that his opening statement is totally false. The Lumeniferous Aether... The story of Art Unwin's long lost cousin. chortle.. |
#5
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The nature of Free Space (Once called, "The Lumeniferous Aether")
wrote:
On Saturday, September 12, 2015 at 6:52:44 PM UTC-5, Wayne wrote: As I understand Gareth's assertion, at every position on the point source sphere, the field strength would be lower than for a bigger antenna replacing the point source. I doubt that is true. He's trying to blame the poor old radiator, "free space", or the "Aether" for rig to feed line to radiator matching losses. My reason to even join this circus is to bring to his attention that his opening statement is totally false. The Lumeniferous Aether... The story of Art Unwin's long lost cousin. chortle.. It seems quite evident that Gareth's mental state has recently deteriorated even further than its usual squalid depths. -- STC // M0TEY // twitter.com/ukradioamateur |
#6
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The nature of Free Space (Once called, "The Lumeniferous Aether")
Stephen Thomas Cole wrote:
wrote: On Saturday, September 12, 2015 at 6:52:44 PM UTC-5, Wayne wrote: As I understand Gareth's assertion, at every position on the point source sphere, the field strength would be lower than for a bigger antenna replacing the point source. I doubt that is true. He's trying to blame the poor old radiator, "free space", or the "Aether" for rig to feed line to radiator matching losses. My reason to even join this circus is to bring to his attention that his opening statement is totally false. The Lumeniferous Aether... The story of Art Unwin's long lost cousin. chortle.. It seems quite evident that Gareth's mental state has recently deteriorated even further than its usual squalid depths. Have you nothing to say on the subject of aerials? You could at least correct the spelling of "luminiferous" if you have nothing else useful to say. -- Roger Hayter |
#7
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The nature of Free Space (Once called, "The Lumeniferous Aether")
Roger Hayter wrote:
Stephen Thomas Cole wrote: wrote: On Saturday, September 12, 2015 at 6:52:44 PM UTC-5, Wayne wrote: As I understand Gareth's assertion, at every position on the point source sphere, the field strength would be lower than for a bigger antenna replacing the point source. I doubt that is true. He's trying to blame the poor old radiator, "free space", or the "Aether" for rig to feed line to radiator matching losses. My reason to even join this circus is to bring to his attention that his opening statement is totally false. The Lumeniferous Aether... The story of Art Unwin's long lost cousin. chortle.. It seems quite evident that Gareth's mental state has recently deteriorated even further than its usual squalid depths. Have you nothing to say on the subject of aerials? You could at least correct the spelling of "luminiferous" if you have nothing else useful to say. What's to say? Gareth has poured a bucket of faeces into the group, there's precisely zero useful conversation to have with the gibbering idiot on the subject of antennas. -- STC // M0TEY // twitter.com/ukradioamateur |
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