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Author Topic: 20 meter dipole and a tuner.  (Read 4430 times)
KJ7WC
Member

Posts: 69




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« Reply #15 on: October 31, 2013, 10:44:56 PM »

WB6BYU:

Well, apparently you felt the need to rip apart my post, Dale. Thank you for pointing out the resonance on 20m; however, you seem to have made several assumptions about my [lack of] understanding of the system. I understand the Smith chart and impedance transformations. In the third quote, I could have phrased that statement a bit better, and assumed that someone would point-out the error. You must be an over-achiever with that level of arrogance.

KF5VZW:

I stand by what I said about half-wavelengths. If you give yourself a half-wave on the lowest frequency of operation and run balanced conductor to your tuner, you'll be happy. Make the extra work necessary to install a balanced system and you'll avoid a lot of loss.

For anyone interested in that book, here's a link to the CQ store for Reflections: http://store.cq-amateur-radio.com/Detail.bok?no=183
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W5DXP
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Posts: 3551


WWW

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« Reply #16 on: November 01, 2013, 05:36:06 AM »

Here's an interesting 20m EDZ antenna that tends not to agree with some things said so far. The ladder-line is ARRL Generic 450 ohm line.

Source---50 ohm coax---1:1 choke------41' ladder-line-----EDZ (136-j603 ohms)

The EDZ is clearly non-resonant and is clearly mismatched to the ladder-line with a 9.4:1 SWR on the ladder-line. The loss in the ladder-line is 0.22 dB (95% efficiency). The SWR on the coax is 1:1 and the source sees a load of 50 ohms without a tuner.

Is this a good antenna? Is it resonant or non-resonant? With that terrible mismatch at the antenna feedpoint, why doesn't it need a tuner? Why is it so efficient?
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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.
K0ZN
Member

Posts: 1542




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« Reply #17 on: November 01, 2013, 07:57:13 PM »


KJ7WC:  Understand how you feel.  It gets real frustrating.....you try to help someone; offer some simple, basic comments to help a beginner and
            someone treats your post like the editors of the IEEE Journal would a research proposal.  I am sure a LOT of the technical overkill just flies over the head of the new guy who just wants a SIMPLE answer and not a mathematical analysis of complex matching, etc.

I have pretty much quit commenting on here because the excessive technical analysis of what is intended to be a SIMPLE explanation. If you make a SIMPLE explanation or recommendation (and don't cover ALL the technical bases, parameters, scenarios, alternatives, etc.) the post will get hyper analyzed.    Whatever............

              .....and I am sure this post will draw some fire...... 

 73,    K0ZN
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KJ7WC
Member

Posts: 69




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« Reply #18 on: November 01, 2013, 08:24:21 PM »

No flames from me, K0ZN.

BTW, I like the questions Cecil.
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W5DXP
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Posts: 3551


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« Reply #19 on: November 02, 2013, 09:48:43 AM »

... the post will get hyper analyzed...

Smiley"hyper analyzed" is not in The IEEE Dictionary.Smiley
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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.
W9FIB
Member

Posts: 651




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« Reply #20 on: November 03, 2013, 05:13:05 AM »

No flames here either. But I do enjoy seeing a basic answer, and then an "in depth" answer. The basic answer makes me interested in the "why it works". So when someone goes into detail, there is usually an answer to the "why it works". To somebody who does not understand the "why it works", then yes the in depth answer is a waste of time. But to me, the more detail presented, the more I can learn.

I am in the process of designing the lightest weight, shortest length, most efficient antenna that covers 40 - 10 M to use on my dx vacation to the Philippines. So the "why it works" is very helpful.

So the thing to remember is that the forum can be a wealth of information. And those who "teach" beyond the basics are appreciated by those who may already know the basics, but want to learn more. But the basic answer works well for those who are just looking for the quick answer. So both are useful to the readers.

The audience is often more then the original poster! So kudos to those who provide any type of answer. Smiley
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