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No antennae radiate all the power fed to them!
On 11/3/2014 3:48 PM, wrote:
rickman wrote: On 11/3/2014 3:09 PM, wrote: rickman wrote: On 11/3/2014 1:07 PM, wrote: rickman wrote: On 11/2/2014 4:11 PM, wrote: Lostgallifreyan wrote: wrote in : The only external heat source in space is the Sun; solution, sun shade. Maybe not. I just did a bit of Googling for 'superconductors in space' minus quotes. There's a lot of statements abotu space missions ended because required helium or hydrogen coolant ran out, Yeah, the coolent ran out for the things that GENERATE a lot of heat and need to be cooled more than radiation can provide. Radiative cooling does not provide for a lot of cooling. and also of space having latent temperatures up to 100K, so a sun shade won't help a lot there with current materials. There really is no such thing as temperature in space as it is a vacuum. That is a gross oversimplification. The temperature of space is the temperature of the background radiation, even in a near vacuum. That is also an simplification. But not a gross oversimplification. True. Shall we go into why an ordinary thermometer exposed to the Sun at about Earth's distance from the Sun allowed to stabilze will read the tempurature of space as about 7 C and what are the unstated assumptions for this to happen? The number I found was about 4 °C. I believe it was posted with all the assumptions... I didn't see that post. If it has already be done, so be it. It is just the assumption that the object is a round, highly conductive, black body so that it absorbs all radiation hitting it and spreads the heat so it is isothermal and re-radiates it at that temperature the same in all directions. Sort of an inside out integrating sphere. This was the post where I quoted a formula that said the energy from the sun would produce 77 °K at about 13 AU. -- Rick |
No antennae radiate all the power fed to them!
"Lostgallifreyan" wrote in message
. .. wrote in : You write like a starry eyed dreamer that believes long established principals are going to go away simply by putting something in space. Actually, no. My point has more to do with establishing precedent, aimed at getting a mass public interested Your ramblings are irrelevant to amateur radio, and, as such, you are a troll who is polluting these NG. |
No antennae radiate all the power fed to them!
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No antennae radiate all the power fed to them!
On 11/3/2014 4:05 PM, wrote:
On Monday, November 3, 2014 2:01:21 PM UTC-6, rickman wrote: On 11/3/2014 12:13 PM, wrote: On Monday, November 3, 2014 11:05:11 AM UTC-6, gareth wrote: "Lostgallifreyan" wrote in message . .. How many other people who are not engineers or scientists do you see posting around here? In discussions about short antennae, quite a few from Yankland. I'm just a regular ole ham here. Never studied any of this stuff in school, and don't work in any related field. Everything I've learned, I learned on my own. Mainly from books, of which I have several. I trust good textbooks a lot more than I trust usenet jibber jabber. Usenet jibber jabber is only as good as the qualifications of the one jabbering. Some info is good, some is bad, and some is pure unadulterated bafflegab. Will you do us *all* a favor and stop replying to him? You keep feeding the tosser... er, I mean troll. -- Rick Why don't you kiss my differential. If I want to reply to him I will, and I don't care if chaps the ass of every "Rick" on the planet. No one is holding a pistol to your head making you read it. Exactly, and the same goes for your rants to Gareth. No one is making you read his nonsense. But both of you make this group a less pleasant group. -- Rick |
No antennae radiate all the power fed to them!
On 11/3/2014 4:23 PM, gareth wrote:
"rickman" wrote in message ... On 11/3/2014 12:13 PM, wrote: On Monday, November 3, 2014 11:05:11 AM UTC-6, gareth wrote: "Lostgallifreyan" wrote in message . .. How many other people who are not engineers or scientists do you see posting around here? In discussions about short antennae, quite a few from Yankland. I'm just a regular ole ham here. Never studied any of this stuff in school, and don't work in any related field. Everything I've learned, I learned on my own. Mainly from books, of which I have several. I trust good textbooks a lot more than I trust usenet jibber jabber. Usenet jibber jabber is only as good as the qualifications of the one jabbering. Some info is good, some is bad, and some is pure unadulterated bafflegab. Will you do us *all* a favor and stop replying to him? You keep feeding the tosser... er, I mean troll. The other ignorant yank redneck vomits his usual verbal diarrhoea. Why be happy in your state of igorance, when, with a little reading around and self-training you could be an expert yourself? I screwed up. My post triggered a reply which is the last thing I want. -- Rick |
No, antennae radiate all the power fed to them!
On Sat, 01 Nov 2014 15:32:03 -0400, rickman wrote:
On 11/1/2014 11:26 AM, gareth wrote: Ignoring, for the moment, travelling wave antenna, and restricting discussion to standing wave antennae ... A wave is launched, and radiates SOME of the power, and suffers both I2R losses and dielectric and permeability losses associated with creating and collapsing the near field. At first, there is no standing wave, until the wave reaches the point of reflection in the antenna and heads back the way it has come (because not all has been radiated*****) On the way back, it againn suffers the losses described above, as well as radiating a bit more. It then reaches the other end and suffers further reflections ad infinitum. An interesting conclusion is, therefore, that the I2R losses are repeated, each tiome with a smaller loss, as the wave decrements. ***** Without the remnants of non-radiated power, there could NOT be a standing wave! I think the subject says it all. Yes, antennae radiate all the power fed to them. The larger part as electromagnetic wave, the smaller part as infrared radiation. w. |
No antennae radiate all the power fed to them!
wrote in message
... About what? I read what I need to read in order to do whatever it is I need to do. I don't need to read any more about small antennas in order to deal with the likes of you. As you recall, I was probably the first one to jump on you when you falsely claimed that small radiators are inefficient. Anyone that has actually read up on the subject knows that that is not true. If anyone needs to invest in some good textbooks on the subject, it's you. Based upon what you write, I suspect that your textbooks were written by Dr.Seuss. The most advanced of my textbooks, which was a course textbook back in the early 1970s was, "Fields and Waves in Communications Electronics" by Ramo, Whinnery and Van Duzer; Ramo and Whinnery being the R and the W in TRW. Short antennae are poor radiatiors. I refer you to the book, "Antennas" by "Those Engineers Ltd", a Yank book from 1948 that discusses that issue. |
No antennae radiate all the power fed to them!
On 11/3/2014 3:43 PM, Lostgallifreyan wrote:
rickman wrote in : The reason why cooling something gets harder as it approaches absolute zero is because the heat flow is proportional to the difference in temperature. Even if your pump is perfect and acts as if you put the thing being cooled in contact with a heat sink at 0 °K, the rate of heat flow decreases as that temperature delta diminishes. Ok, that helps. It's close to what I had in mind, though my reasoning may still be bad. For what it's worth... if a superconductor is very cold, needing to be so, then because there is no way to go below zero K, there are more things hotter, than colder, so they have more effect than the shaded space conditions. That balance might favour a need for forced cooling just to play safe in many cases, but I accept that isolation might be fairly easy to do, and I also accept that 77K is likely far enough above shaded space conditions that it gives a wide margin to prevent small leaks from nearby heat sources causing failure. There is nothing at all in your posts that is based on any facts. Science and engineering don't work on "might favor". Get the equations and do the math. Otherwise it is just waving hands and flapping gums. -- Rick |
No antennae radiate all the power fed to them!
"rickman" wrote in message
... Get the equations and do the math. Physician, heal thyself. |
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