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Posted: 10/6/2007 4:42:18 PM EDT
[#1]
You can try loading the elements, but I'm wondering why? An AR15 is bigger than a 3 el 2m yagi and the reflector is no longer than your arm.
Doesn't get much easier than a simple 2m beam...remember, the element (diameter) determine bandwidth. |
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Posted: 10/6/2007 4:52:52 PM EDT
[#2]
Normally I'd have a response but I'll reserve it after that code thread.
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Posted: 10/6/2007 4:59:11 PM EDT
[#3]
all the lengths are "critical"
and "critical" is a relative term. your reflector is typically larger than your driven element and just the opposite for your directors. get an antenna book or look on line for calculating element length. |
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Posted: 10/7/2007 12:49:45 AM EDT
[#4]
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Posted: 10/7/2007 9:16:32 AM EDT
[#5]
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Posted: 10/7/2007 1:45:08 PM EDT
[#7]
Feel free to kiss my ass now.
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Posted: 10/7/2007 1:56:28 PM EDT
[#8]
If you scale down an antenna, it operates at a proportionally higher frequency range.
CJ |
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Posted: 10/7/2007 2:31:47 PM EDT
[#9]
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Posted: 10/7/2007 3:16:31 PM EDT
[#10]
No, really.
 These smileys are great fun. |
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Posted: 10/7/2007 3:30:52 PM EDT
[#11]
Ok, what code thread? Sounds like someone got their coax in a bunch 
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Posted: 10/7/2007 3:34:51 PM EDT
[#12]
No comment.
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Posted: 10/7/2007 6:35:04 PM EDT
[#13]
Go look up 4nec2, which is one of the free antenna modelling programs. Note that without a modelled feedline and a ground plane and the mount and so on, you're (over)simplifying, but at least you can get some ideas of what will happen on the frequencies you're interested in.
I've only glanced at it myself - I have yet to figure out how to add anything to a model (or even modify it, really, other than hand editing the text file), but I didn't spend more than a few minutes with it, either. |
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Posted: 10/7/2007 6:38:21 PM EDT
[#14]
How's about a folding version of a 2m handheld yagi? This is on my list of projects in the near-term. Collapses down pretty nicely! Oh, and I don't think there's an easy way to change the element lengths on a homebrew beam such as this, since it's basically a dipole antenna if you ignore the director/reflector. The driven must be resonant on the op frequency and the other elements are set at pre-calculated lengths and spacing for the best directional effect.
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Posted: 10/7/2007 9:43:42 PM EDT
[#15]
2 meter antennas have to be some of the easiest to make. When I first got my license, I was using nothing more than an ancient Kenwood HT hooked up to a variety of home made antennas ranging from coat hanger 1/4 wave groundplanes to 3 and 5 element beams made of 12ga solid copper wire and 2x2 lengths of wood. There is plenty of info online on how to make them, or get some of the ARRL antenna books.
I'm sure there's probably going to be a few useful links if you dig around at www.ac6v.com. And then there are the totally insane things that I do... Lots of bamboo and 70 feet of wire 
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Posted: 10/8/2007 2:53:34 AM EDT
[#16]
Not always...there are many options to shorten a yagi. It's quite common to see them on HF antennas where element lengths can get quite long, but it's too simple and easy to build a full size yagi for 2m. There are many comprises with shortened yagi's. |
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Posted: 10/8/2007 4:10:21 AM EDT
[#17]
Ok, you might not win the internet, but you win this thread Now just what is that for? That's Hamsexy
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Posted: 10/8/2007 4:47:05 AM EDT
[#18]
I need to finish mine. I've had everything done except the SO239 connector for a couple of months. You'd think I could get off my butt long enough to solder the stupid thing on.  fwiw you can get steel tape measures at Harbor Freight dirt cheap. This is about all they're good for. I bought two. The one I didn't cut up won't go back into the case. But for the price I didn't expect much.
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Posted: 10/8/2007 4:34:14 PM EDT
[#19]
It was an experiment to create a mobile NVIS antenna for 80/40m. Not as successful as I had hoped. I might try it again someday, hopefully slightly more compact
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