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Building a Mil-Air Antenna

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trainman111

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This question is directed to anyone who can answer it but specifically to ka3jjz.

Mike, earlier in my mil-air post (before it went off topic, sorry, I didn't even realize it should have been in the antenna forum) you told me about an idea when building the ground-plane antenna. you said,

"In fact, let me throw something else out here - you can make the ground plane dual band by cutting one vertical element for one set of freqs (say 140 mhz - which will put you right in the middle of the 138-144 milair band, where many air national guards hang out...) another vertical element for 300 mhz or so. Cut the radials 5% longer than the 140 mhz element and you should be good to go."

How do I put two vertical elements in one so239 socket?? Anyone have pictures of how this is done that I can see whatt I should be doing...

Nick
 

ka3jjz

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I've said this before, Nick, and will repeat it again - that information is in the Wiki. There's a project there that describes building a 2m/440 dual band ground plane that would work almost the same way. The name of the article is "The NA4IT Cheap Dual Band Ground Plane"
If you go to the main page, you will see on the left frame 'Wiki Categories'; select 'Antennas', then from that article, 'Scanner Antennas' - that page has a section for homebrew projects, including the well known Off Center Fed dipole. There's also a link for the dual band ground plane. His pix are pretty good, so you should be able to adapt what he did for your purposes.

A ground plane, and the Off Center Fed Dipole are, I think, 2 of the easiest antennas to build - and the dipole might have the edge for being more broadbanded. Both are good starter projects. Enjoy.

73s Mike
 
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trainman111

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Thanks Mike,
Sorry for being such a pain...I saw the NA4IT one before but I never realized what it was unitl now...now its time to start building!

Nick
 

gcgrotz

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A 1/4 wave whip for VHF works fairly well at the third harmonic as a 3/4 wavelength like 155/465 MHz. That's what I use on my truck, a 19" whip and mag mount.
 
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