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Author Topic: 43 Ft Vertical Blatant Lie  (Read 35898 times)
W5DXP
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« Reply #45 on: September 24, 2012, 06:46:23 AM »

Nothing I said disagrees with the fact there might be some cases where delay is large or where an inductor does not behave like a single lumped component.

Point is a 75m Texas Bugcatcher coil does not behave like a single lumped component. How do you explain the EZNEC simulations and university EE lab measurements that completely disagree with the results of a lumped component analysis? Even EZNEC gets wildly different results when a Texas Bugcatcher coil is modeled as a lumped inductor vs modeled using the helix option. The lumped inductor results completely disagree with the lab measurements while the helix modeling results correlate nicely.

http://www.w5dxp.com/BugTest1.JPG

Quote
I haven't found any that can replace an inductor, over a wide frequency range, with a simple transmission line.

Mainly because those large air-core loading coils have a Z0 characteristic impedance in excess of 2000 ohms. Here's how to replace the entire tuner with transmission line.

http://www.w5dxp.com/notuner.htm

Quote
For example a plate choke at lowest series resonance behaves quite well like back-to-back L networks.

Why do you insist on changing the subject away from large air-core loading coils? A lumped-circuit design works just fine for a lot of applications. I'm talking about the times when a lumped-circuit analysis yields completely invalid results like the BugTest1.JPG results above. Wouldn't you agree that when the lumped-circuit results are wildly inaccurate that it is time to used the distributed network model?

Quote
As another example, a long radial-mode helical antenna could have considerable "electrical degrees" of length. I've never said otherwise, in the full context of what I actually said and not what someone says I have said.

On the contrary, you have said otherwise. Here's a quote from your web page concerning that large air-core loading coil that you tested. A 3 ns delay at 4 MHz is 4.3 degrees. Yet the Hamwaves inductance calculator says it is about 30 degrees long.

"Phase delay of current is also essentially zero. Only voltage decreases and changes phase along the length of the loading coil."

Those are false statements as can be seen from the following EZNEC simulation:

www.w5dxp.com/bugctchI.zip

The voltage at the source end of the coil is 257v at 0 degrees.
The current at the source end of the coil is 0.1a at 0 degrees.

The voltage at the load end of the coil is 257v at -42 degrees.
The current at the load end of the coil is 0.1a at -42 degrees.

That sure looks like a matched 42 degree long transmission line to me. The reason that your results look otherwise is because of the 100:1 mismatch existing during your measurements. Instead of a load of 50 ohms, if you loaded your coil with a resistor equal to the coil's characteristic impedance (~4000 ohms) you would see the same transmission line effects as reported above.

These results correlate to the measurements made in a university EE lab. They disagree with the above statement from your web page and wildly disagree with the results of a lumped-circuit analysis.

It's easy to uncover your error. Measure the phase delay through 30 degrees of Z0=600 ohm feedline terminated with an 8 ohm resistor. Your measured phase delay will be about 3 ns. Would you then argue that the RF signal is jumping from one end of the 30 degree long transmission line to the other end in 3 ns? You said that about your coil. To be consistent, you should say the same thing about a transmission line.

Tom, your postings on this subject are devoid of any technical content. Please explain the transmission-line-like effects above and in EE lab measurements.
« Last Edit: September 24, 2012, 07:08:07 AM by W5DXP » Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
G3TXQ
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« Reply #46 on: September 24, 2012, 08:26:55 AM »

Nope, it doesn't alter that fact. But of these two explanations of why the sky is blue, which is the most accurate?

1. My Mother's explanation: The sky is blue because God made it blue.

2. My explanation: The sky is blue because of the nitrogen content in the atmosphere.

Both explanations say the sky is blue but one is based on religion and one is based on physics. Which would you chose?


I choose to believe both explanations - they are not mutually exclusive!

Steve G3TXQ
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W5DXP
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« Reply #47 on: September 24, 2012, 08:49:31 AM »

I choose to believe both explanations - they are not mutually exclusive!

Smiley I guess that analogy doesn't work for religious people so here is a technical question for you. Given a black box with an unknown component inside:

Does the measured phase delay through the black box accurately predict the number of electrical degrees occupied by the contents of the black box?

Please note that the phase delay in one element of a dipole from the feedpoint to the tip end of the dipole is about 3 degrees while we know the element is electrically 90 degrees long.
« Last Edit: September 24, 2012, 08:51:28 AM by W5DXP » Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
W8JI
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« Reply #48 on: September 24, 2012, 08:52:27 AM »

Hijacking of threads to pontificate about a pet theory really gets old after several years. I gave up reading that same old repeating stuff years ago, although I certainly do read what new contributors say.

Unfortunately, it just destroys or confuses threads.
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WX7G
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« Reply #49 on: September 24, 2012, 10:03:00 AM »

http://www.eham.net/articles/27057
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W5DXP
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« Reply #50 on: September 24, 2012, 11:28:50 AM »


That article is Rev. 1.3. An updated and expanded version, Rev. 1.8, is available on my web page at:

http://www.w5dxp.com/coilmeas.htm
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73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
W5DXP
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« Reply #51 on: September 24, 2012, 11:58:27 AM »

Hijacking of threads to pontificate about a pet theory really gets old after several years.

Smiley Correcting your technical mistakes is not hijacking a thread. The fact that you offer no technical defense for your concepts and no technical argument for proving mine wrong speaks volumes. If you would repeat your coil bench test, you would find a value of load resistor equal to the coil's Z0 that proves your coil is about 30 degrees long on 4 MHz with a propagation delay of about 22 ns while exhibiting transmission line effects.

The mistake with your last measurement was using standing-wave current to try to measure phase delay but pure standing-wave current doesn't change phase from one end of the coil to the other. When standing wave magnitude is high, phase delay is useless for calculating propagation delay. You have got to know that by now as it is easy to demonstrate such using transmission lines.
« Last Edit: September 24, 2012, 12:05:56 PM by W5DXP » Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
KB4QAA
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« Reply #52 on: September 24, 2012, 12:33:34 PM »

Cecil,
I'm disappointed that you started up this coil nonsense again.  You had worked your way back into my graces and I was enjoying reading your other contributions.

While I can't pretend to fully understand the discussions, I think I can recognize either a shell game of "it's electrical degrees, no mechanical degrees, no delay, no eznec, no laboratory results, etc.   Put another way "Where does my lap go when I stand up?".

I refuse to believe that you have discovered some principle that Mr. Faraday, et al, didn't already know.

Which leads me to the conclusion that you are just doing this to bait arguments.

Please stop hijacking other's threads and keep your pet theories within your threads.

73, Bill

[edit]   I don't reject your arguments outright, and find the discussion worthwhile to a point.  In the end, I think it is important to understand that there is more than one way to model coils, depending on your needs. 
« Last Edit: September 24, 2012, 01:01:06 PM by KB4QAA » Logged
M6GOM
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« Reply #53 on: September 24, 2012, 02:16:44 PM »

Is this the guy who claims to have re-written the laws of physics yet refuses to have his claims put to test on a proper antenna test range?
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W5DXP
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« Reply #54 on: September 24, 2012, 04:11:29 PM »

I refuse to believe that you have discovered some principle that Mr. Faraday, et al, didn't already know.

Bill, there is absolutely nothing new in what I am saying. Both the lumped-circuit model and distributed network model have been around since long before I was born. Contrary to your false implication above, I have never claimed to have discovered anything new. All I have done is point out some well known limitations in the lumped-circuit model and the technical conceptual mistakes that some people make because of those limitations.

In particular, when we are analyzing a coil like a 75m Bugcatcher coil, a lumped inductor model will yield invalid results while the distributed network model will yield valid results. This has been confirmed by university EE lab measurements.

Understanding the transmission line characteristics of 75m mobile loading coils could lead to improvements in 75m mobile antenna performance and that would be a good thing.
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73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
RFRY
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« Reply #55 on: September 24, 2012, 04:56:42 PM »

Those are false statements as can be seen from the following EZNEC simulation: <snip>

The voltage at the source end of the coil is 257v at 0 degrees.
The current at the source end of the coil is 0.1a at 0 degrees.

The voltage at the load end of the coil is 257v at -42 degrees.
The current at the load end of the coil is 0.1a at -42 degrees.

That sure looks like a matched 42 degree long transmission line to me.

So it may look like to you.  But even if that were true, should you or anyone else necessarily ascribe that coil to produce the radiation resistance and other radiation properties of a 42-degree linear conductor?
« Last Edit: September 24, 2012, 05:48:11 PM by RFRY » Logged
W5WSS
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« Reply #56 on: September 24, 2012, 05:48:49 PM »

RFRY what you just said is correct.

and may I add that never will a maximum efficient loading coil anywhere in the series placement along a vertical can the coil itself develope more field strength than if the physical length were available.in the first place.

But that is not what Cecil is contending.
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W5DXP
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« Reply #57 on: September 25, 2012, 05:20:00 AM »

But that is not what Cecil is contending.

Exactly, I have made no assertions about radiation which depends upon the physical length of the antenna. Talking about radiation is an obvious diversion away from what I am talking about.

However, the phasing of the currents has an effect on radiation. Witness the phasing coils in a vertical collinear antenna for 440 MHz. I am hoping that after we get the analysis of the antenna currents correct that then we can possibly design better antennas by taking advantage of the phasing inherent in large air-core loading coils like a 75m Bugcatcher loading coil.

My discussions are about the electrical length of the antenna, not the physical length. The phase of the feedpoint impedance depends upon the electrical length of the antenna. At the first frequency where the feedpoint impedance is purely resistive, a monopole (or one element of a dipole) is 90 degrees long electrically, no matter how long it is physically. However, for standing wave antennas, the magnitude of the feedpoint impedance is affected by the magnitude of the reflected wave which is affected by physical length.

So it may look like to you.  But even if that were true, should you or anyone else necessarily ascribe that coil to produce the radiation resistance and other radiation properties of a 42-degree linear conductor?

Those conditions indicate a matched transmission line with Z0=2571 ohms and a propagation delay of 42 degrees. With copper selected for the coil, EZNEC says the source power is 25.71 watts and the load power is 25.69 watts, i.e. 0.08% of the power is lost in/from the coil. We are only 0.08% inaccurate if we assume there are no I^2*R losses or radiation losses from the coil. 99.92% accuracy seems acceptable to me.

Of course, when we install the coil in a standing-wave antenna, the coil losses go up but the transmission line effects inherent in a large air-core loading coil prohibit it from doing much radiating. If one denies the transmission line effects in a large air-core loading coil, one is handicapped in trying to explain why it doesn't do much radiating.
----------------------------------------------------------------------------------------------
To all who object to my previously posted technical information:

My postings are not intended to upset newsgroup participants. Omniscient gurus, whining, and newsgroup politics seem out of place on a technical newsgroup. I always welcome formulas, math models, and measurements. Please feel free to offer any technical data that will disprove the existence of transmission line effects in large 75m mobile air-core loading coils or lumped-circuit calculations that agree with modeling and measurements.
« Last Edit: September 25, 2012, 05:50:21 AM by W5DXP » Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
RFRY
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« Reply #58 on: September 25, 2012, 05:55:35 AM »

Exactly, I have made no assertions about radiation which depends upon the physical length of the antenna. Talking about radiation is an obvious diversion away from what I am talking about.

However, the phasing of the currents has an effect on radiation.

Looks like you are talking about radiation.

The chief purpose of a base loading coil is to permit the current and voltage at the feedpoint to be in phase with each other (unity power factor).

This condition permits maximum transfer of the power available from the source to the linear conductor, where the r-f current then flowing along that linear conductor produces EM radiation.

However that base-loaded, resonant, short monopole still has essentially the same radiation resistance and radiation pattern it had before the loading coil was added -- not those of a linear, 90-degree monopole.
« Last Edit: September 25, 2012, 06:38:48 AM by RFRY » Logged
W8JI
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« Reply #59 on: September 25, 2012, 06:20:48 AM »

RFRY what you just said is correct.

and may I add that never will a maximum efficient loading coil anywhere in the series placement along a vertical can the coil itself develope more field strength than if the physical length were available.in the first place.

But that is not what Cecil is contending.

Please tell me what Cecil is saying.
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