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Is this a proper defenition?
resonant antenna [′res·ən·ənt an ′ten·ə]
(electromagnetism) An antenna for which there is a sharp peak in the power radiated or intercepted by the antenna at a certain frequency, at which electric currents in the antenna form a standing-wave pattern. McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc. I thought a resonant antenna was resistive without any reactance. Mikek |
Is this a proper defenition?
On Wednesday, August 22, 2012 7:47:07 PM UTC-5, amdx wrote:
I thought a resonant antenna was resistive without any reactance. Consider a transmission line with standing waves. There is a point every 1/2WL where the impedance is a low "resistance without any reactance". That is the point where the standing wave voltage is in phase with the standing wave current. A 1/2WL dipole is a standing wave antenna with an SWR on the antenna of approximately 20:1. At the center feedpoint, the standing wave voltage is in phase with the standing wave current so the feedpoint impedance is "resistive without any reactance". If you look at the current and voltage distribution on a standing wave antenna you will find that it looks just like the current and voltage distribution on a transmission line with reflections. http://www.learn-about-electronics.c...d-voltage.html http://vsagar.com/2012/02/23/voltage...ipole-antenna/ -- 73, Cecil, w5dxp.com |
Is this a proper defenition?
On 8/22/2012 7:47 PM, amdx wrote:
resonant antenna [′res·ən·ənt an ′ten·ə] (electromagnetism) An antenna for which there is a sharp peak in the power radiated or intercepted by the antenna at a certain frequency, This is not correct. at which electric currents in the antenna form a standing-wave pattern. The standing waves will exist whether resonant or not. McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc. I thought a resonant antenna was resistive without any reactance. Mikek It is resistive *at the feedpoint* when properly made. John |
Is this a proper defenition?
On Thursday, August 23, 2012 9:36:23 AM UTC-5, John S wrote:
An antenna for which there is a sharp peak in the power radiated or intercepted by the antenna at a certain frequency, This is not correct. At 14.32 MHz a certain dipole accepts 159.2w from a 100v source into a resonant 62.8 ohm feedpoint impedance. At 14.25 MHz, it accepts 160.2w from a 100v source into a non-resonant 61.9-j6 ohm feedpoint impedance. So it appears that you are technically correct but maybe splitting hairs.:) -- 73, Cecil, w5dxp.com |
Is this a proper defenition?
On Wednesday, August 22, 2012 7:47:07 PM UTC-5, amdx wrote:
resonant antenna [′res·ən·ənt an ′ten·ə] (electromagnetism) An antenna for which there is a sharp peak in the power radiated or intercepted by the antenna at a certain frequency, at which electric currents in the antenna form a standing-wave pattern. Seems that these conditions would also exist for any conjugately matched non-resonant standing-wave antenna. |
Is this a proper defenition?
On 8/23/2012 3:22 PM, W5DXP wrote:
On Thursday, August 23, 2012 9:36:23 AM UTC-5, John S wrote: An antenna for which there is a sharp peak in the power radiated or intercepted by the antenna at a certain frequency, This is not correct. At 14.32 MHz a certain dipole accepts 159.2w from a 100v source into a resonant 62.8 ohm feedpoint impedance. At 14.25 MHz, it accepts 160.2w from a 100v source into a non-resonant 61.9-j6 ohm feedpoint impedance. So it appears that you are technically correct but maybe splitting hairs.:) -- 73, Cecil, w5dxp.com It does not say "a sharp peak in the power *accepted*" by the antenna. John |
Is this a proper defenition?
On 8/23/2012 3:22 PM, W5DXP wrote:
On Thursday, August 23, 2012 9:36:23 AM UTC-5, John S wrote: An antenna for which there is a sharp peak in the power radiated or intercepted by the antenna at a certain frequency, This is not correct. At 14.32 MHz a certain dipole accepts 159.2w from a 100v source into a resonant 62.8 ohm feedpoint impedance. At 14.25 MHz, it accepts 160.2w from a 100v source into a non-resonant 61.9-j6 ohm feedpoint impedance. So it appears that you are technically correct but maybe splitting hairs.:) -- 73, Cecil, w5dxp.com You just showed that the off-resonant antenna accepts *more* power than the resonant one. That is not a "sharp peak." John |
Is this a proper defenition?
On 8/23/2012 3:22 PM, W5DXP wrote:
On Thursday, August 23, 2012 9:36:23 AM UTC-5, John S wrote: An antenna for which there is a sharp peak in the power radiated or intercepted by the antenna at a certain frequency, This is not correct. At 14.32 MHz a certain dipole accepts 159.2w from a 100v source into a resonant 62.8 ohm feedpoint impedance. At 14.25 MHz, it accepts 160.2w from a 100v source into a non-resonant 61.9-j6 ohm feedpoint impedance. So it appears that you are technically correct but maybe splitting hairs.:) -- 73, Cecil, w5dxp.com You used a fixed 100V source. If you can do that, I can use a fixed 1A source. In that case a resonant antenna of 62.8 ohms feedpoint resistance will radiate very nearly 62.8W. An antenna with a feedpoint impedance of 62.8 + j50 will radiate very near 62.8W. There is no sharp peak in the power radiated whether at resonance or not. The definition as it stands is incorrect. |
Is this a proper defenition?
On Friday, August 24, 2012 12:25:23 PM UTC-5, John S wrote:
You used a fixed 100V source. Let's modify the definition until you agree with it. How about? resonant antenna [′res·ən·ənt an ′ten·ə] (electromagnetism) An antenna in which there is a peak in the standing wave energy on the antenna at a certain frequency during receive when configured as an unloaded parasitic element using a constant power, variable frequency source for the incident RF fields. Would you agree that that energy peak indicates antenna resonance? -- 73, Cecil, w5dxp.com |
Is this a proper defenition?
On 8/25/2012 8:59 AM, W5DXP wrote:
On Friday, August 24, 2012 12:25:23 PM UTC-5, John S wrote: You used a fixed 100V source. Let's modify the definition until you agree with it. How about? resonant antenna [′res·ən·ənt an ′ten·ə] (electromagnetism) An antenna in which there is a peak in the standing wave energy on the antenna at a certain frequency during receive when configured as an unloaded parasitic element using a constant power, variable frequency source for the incident RF fields. Would you agree that that energy peak indicates antenna resonance? -- 73, Cecil, w5dxp.com I'm sure you've heard the saying "Never mud wrestle with a pig..." |
Is this a proper defenition?
On Fri, 24 Aug 2012 05:20:25 -0700 (PDT), W5DXP
wrote: Seems that these conditions would also exist for any conjugately matched non-resonant standing-wave antenna. I hope I am never foolish enough to challenge your wisdom Cecil! de W8CCW John Ferrell W8CCW |
Is this a proper defenition?
On Saturday, August 25, 2012 2:04:58 PM UTC-5, John Ferrell wrote:
I hope I am never foolish enough to challenge your wisdom Cecil! Just paraphrasing Walter Maxwell, w2du (SK). -- 73, Cecil, w5dxp.com |
Is this a proper defenition?
On 8/25/2012 8:59 AM, W5DXP wrote:
On Friday, August 24, 2012 12:25:23 PM UTC-5, John S wrote: You used a fixed 100V source. Let's modify the definition until you agree with it. How about? resonant antenna [′res·ən·ənt an ′ten·ə] (electromagnetism) An antenna in which there is a peak in the standing wave energy on the antenna at a certain frequency during receive when configured as an unloaded parasitic element using a constant power, variable frequency source for the incident RF fields. Would you agree that that energy peak indicates antenna resonance? -- 73, Cecil, w5dxp.com Would you agree that my previous statements are correct? |
Is this a proper defenition?
On Sunday, August 26, 2012 4:46:16 PM UTC-5, John S wrote:
Would you agree that my previous statements are correct? Going back how many years?:) -- 73, Cecil, w5dxp.com |
Is this a proper defenition?
On 8/26/2012 5:51 PM, W5DXP wrote:
On Sunday, August 26, 2012 4:46:16 PM UTC-5, John S wrote: Would you agree that my previous statements are correct? Going back how many years?:) -- 73, Cecil, w5dxp.com If you have to ask, then you are just being an asshole as usual. You always want to have an argument whether you are right or wrong. That's why I referred to wrestling a pig. Go screw with somebody else, pig. |
Is this a proper defenition?
On Sunday, August 26, 2012 8:32:23 PM UTC-5, John S wrote:
On 8/26/2012 5:51 PM, W5DXP wrote: Would you agree that my previous statements are correct? Only a perfect person never makes an incorrect statement. I gave an example where that definition applies to a conjugately matched non-resonant antenna. Of course, all conjugately matched antenna *systems* are resonant whether the antenna is a resonant or non-resonant length. Seems that definition has the same flaw as in Reflections, by Walter Maxwell (SK).. Where he said, "My antenna tuner really does tune my antenna", he probably should have said, "My antenna tuner really does tune my antenna system." The definition should IMO also eliminate the word "sharp" from the definition. A resonant 1/2WL dipole does have a peak but it isn't sharp because of the broad bandwidth. -- 73, Cecil, w5dxp.com |
Is this a proper defenition?
I don't see why both definitions can't be 'true'. One doesn't exclude the other.
- Paul --------------------- On Wednesday, August 22, 2012 7:47:07 PM UTC-5, amdx wrote: resonant antenna [′res·ən·ənt an ′ten·ə] (electromagnetism) An antenna for which there is a sharp peak in the power radiated or intercepted by the antenna at a certain frequency, at which electric currents in the antenna form a standing-wave pattern. McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc. I thought a resonant antenna was resistive without any reactance. Mikek |
Is this a proper defenition?
On Tuesday, August 28, 2012 5:22:46 AM UTC-5, (unknown) wrote:
I don't see why both definitions can't be 'true'. One doesn't exclude the other. The definition of a "resonant antenna" *should* exclude non-resonant antennas just as the definition of a "red car" should exclude non-red cars. A non-resonant antenna that is conjugately matched meets the definition of a resonant antenna. That seems to be ambiguous at best and at worst, a contradiction. Updating the definition: resonant antenna (also applies to a conjugately matched non-resonant antenna) - An antenna for which there is a peak in the power radiated or intercepted by the antenna at a certain frequency, at which electric currents in the antenna form a maximum current standing-wave pattern So much for the myth that resonant antennas radiate better than non-resonant antennas. Consider the following two examples without transmission lines. 50 ohm Source---50 ohm load 100+j100 ohm Source---100-j100 ohm load Which system has the most efficient power transfer efficiency? Has anyone ever considered that if the coax is disconnected from a center-fed half-wavelength antenna, the antenna is no longer resonant and could instead be used for a non-resonant guy wire at that frequency? -- 73, Cecil, w5dxp.com |
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