Towertalk
[Top] [All Lists]

Re: [TowerTalk] Antenna model

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Antenna model
From: jimlux <jimlux@earthlink.net>
Date: Wed, 22 Feb 2017 17:55:24 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 2/22/17 5:16 PM, john nistico wrote:

I used eznec to model a small beam for my son who is going for his
general. 2 element 20 meter yagi on a 10 ft boom the results were
pretty good. Any suggestions on how to improve? The driven element is
16fy 6 inches per side reflector is +10%


It's a two element design, so it's probably not real sensitive to
misalignment or length errors.  But that's one of the real values of
modeling.. you can change the angles (so that the elements aren't
perfectly aligned, like when the clamp slips) and see if the match or
gain change significantly.  Ditto if you are off by an inch in length.

What sort of feed are you using to get 50ohms? uniform diameter tubing for the 10 foot
pieces sticking out each side? what diameter?


Running the optimizer in 4nec2 on the example 2 element yagi, with 10 foot spacing, I get driven element of 16.188 ft (16 ft 2-1/4") and reflector of 16.805 ft (16 ft 9-2/3"), with forward gain of 12.2 dBi and 1.8:1 VSWR (because the Yagi has a 27 ohm feed point impedance.. any sort of matching network will fix that nicely)

Your design seems to tune a bit lower in frequency..it has about 11 dBi gain across the band. But it also has a 1.4:1 match to a 50 ohm line at 14.1.





_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>