Because he is feeding it balanced, not with a unbalanced coax feed.
You could scale to 11m if you were really keen to try.
You could scale to 11m if you were really keen to try.
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Building 102' vertical Antenna for 11 meters...
- Thread starter T23
- Start date
As it has been stated before, you need to crawl before you can walk. Start out simple. Make a simple dipole as examples have been made above. They even put the needed lengths in for you - already. Homer even gave you the diagrams for how to make the same thing a couple of different ways; decent advice at that.
The antenna in the link you provided isn't for the CB band - which is the 11 meter band BTW. It was cut to length for the 160 meter band.
Simple formula:
468 divided by the frequency in mhz (in your case, the frequency is 27.205mhz for CB use) equals 17.2 ft total length. Each side will be 1/2 of that length - or 8.6 ft long. Solder one of these 8.6 ft long wires to the center conductor of a piece of coax, and the other wire to the shield. Attach it between a couple of trees - with enough non-conducting string/cord - and you are done.
Let's say you got you Ham license - and you want to make your first dipole for the 20 meter band. The same formula will apply! We take the "468" number and divide it by 14.205mhz (the 20 meter frequency) and get 32.95 ft overall length - or 16.47 ft for each half.
Notice that when the frequency got smaller (from ~27mhz to ~14mhz) - the antenna got longer?
But if we want to make an antenna for a higher frequency - say 145.230mhz - the antenna gets much shorter. It has to - in order to be resonant.
The higher the frequency; the smaller the antenna will be.
The lower the frequency; the longer it becomes.
Hope this helped some . . .
Any piece of wire will work for receiving signals; but to transmit on the same wire it has to be resonant to that frequency. All we've done is make sure that the lengths are right for some wire to transmit on. Doesn't matter if it is skinny copper wires, steel rods, or 1/2 inch wide aluminum tubes - either will work the same.
Start simple; and build on that experience and success.
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Those two wire going to the house are the feed line for that antenna, parallel conductor, or "ladder line" without the insulators. The distance between those parallel conductors determines the impedance. Not sure about that 25 cm separation, but the resulting impedance is probably around 600 + ohms. And like the author said, since he's using a tuner so the impedance just doesn't matter that much since the mismatch won't affect the feed line like it would with coax.
I think he's got a very nice set up!
- 'Doc
Oh, and yes, it would work for any band, 11 meters included.
I think he's got a very nice set up!
- 'Doc
Oh, and yes, it would work for any band, 11 meters included.
Thanks for being patient with me and my ignorance. I will admit some things don't soak into my brain well without physically seeing it. Thanks, Josh.
