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Author Topic: ZS6BKW Antenna Question  (Read 5956 times)
N4CR
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« Reply #15 on: August 20, 2012, 03:57:11 PM »

Cecil, he was making a joke...
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73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
W5DXP
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« Reply #16 on: August 21, 2012, 04:47:07 AM »

Cecil, he was making a joke...

Actually, I wasn't responding to the joke but to what I thought was a valid question about my IMAXGRAF.EXE program.
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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.
G3TXQ
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« Reply #17 on: August 21, 2012, 05:05:24 AM »

Cecil,

Correct - it was a valid question; the "joke" was in response to Tom's posting!

One other thought about the programme: sometimes I use it to try to find "G5RV/ZS6BKW" solutions, but other times to try to avoid the voltage maxima that would cause problems for a tuner. I wonder how easy it would be to display the voltage maxima? It would probably be too "busy" to display the current maxima and the voltage maxima, so perhaps an option between the two as part of the initial set-up? I know you can interpolate between the current maxima, but my eyesight's not what it was Smiley

It's easy asking for changes - not so easy if you're the implementer Wink

73,
Steve G3TXQ
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W8JI
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« Reply #18 on: August 21, 2012, 05:26:55 AM »

In some multiband matching systems line impedance is fairly critical, so it is good to know what it really is.

Maybe we can get the real line impedance published at the same time the ARRL corrects the loss to realistic values.
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W5DXP
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« Reply #19 on: August 21, 2012, 07:15:19 AM »

I wonder how easy it would be to display the voltage maxima?

Piece of cake - I already display it with my IMAXMIN.EXE software:

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

But simply envisioning a bad point halfway between the good points would be easier.Smiley

In some multiband matching systems line impedance is fairly critical, so it is good to know what it really is.

Yes, good for trying to get closer to 50 ohms but relatively unimportant for simply locating the current maximum (purely resistive) points.

Quote
Maybe we can get the real line impedance published at the same time the ARRL corrects the loss to realistic values.

I once assumed that The Wireman #562 300 ohm transmitting line had a velocity factor of ~0.9 and cut lengths accordingly - it didn't work. Turns out the VF of the particular line that I had bought was closer to 0.8 than it was to 0.9.
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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.
W8JI
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« Reply #20 on: August 21, 2012, 07:26:18 AM »

I don't know why everyone neglects the dielectric in these twin-lead lines with occasional slots in the center. The slots only remove a tiny bit of dielectric effect. They are much closer to twinlead than to open wire because the slots barely have an effect on clean, dry, line characteristics.

I guess they imagine the dielectric isn't there around each wire where the electric fields are strongest, and convince themselves it is like bare conductor open wire line.
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WA9UAA
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« Reply #21 on: August 22, 2012, 05:47:45 PM »

Thanks to all that replied, the resulting discussion was worth the effort Grin. I have about 140 ft of ladder line out now and will simply add the ZS6BKW dipole to my existing 160M dipole.
73,
Rob
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AK4YA
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Posts: 106




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« Reply #22 on: August 26, 2012, 07:38:05 PM »

Thanks to all that replied, the resulting discussion was worth the effort Grin. I have about 140 ft of ladder line out now and will simply add the ZS6BKW dipole to my existing 160M dipole.
73,
Rob

nice that you seem to have a solution here...

anyone have any idea how a zs6bkw mounted only 27ft above ground would work?  I think its supposed to be 40 but thats kinda hairy given my situation
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W5DXP
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« Reply #23 on: August 27, 2012, 05:33:49 AM »

anyone have any idea how a zs6bkw mounted only 27ft above ground would work?  I think its supposed to be 40 but thats kinda hairy given my situation.

On 40m at 27', the approximate gain is 5.5 dBi at 45 deg elevation. Beats a 1/4WL vertical at all elevation angles above 15 deg in the dipole's favored direction. On 20m, it is 9.2 dBi at 35 deg TOA. On 10m, it is 10.3 dBi at 12 deg TOA. Happy DXing on 10m.
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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.
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