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Re: Topband: Antenna thoughts

To: w5jmw@towerfarm.net
Subject: Re: Topband: Antenna thoughts
From: Dave Cuthbert <telegrapher9@gmail.com>
Date: Tue, 2 Mar 2021 09:19:58 -1000
List-post: <mailto:topband@contesting.com>
John, here are EZNEC results for your downward sloping inverted-L and your
T-vertical.

Inverted-L radiation resistance = 8 ohms
T-vertical radiation resistance = 12 ohms

How the radiation efficiency compares depends on your ground system. The
efficiencies for 2.5, 5, and 10 ohm ground systems are compared:
*Antenna    GND R    Rad Eff  * *T over L*
L                   2.5           76%
T                   2.5           83%       0.4dB

L                   5.0            62%
T                   5.0           71%       0.6dB

L                   10            44%
T                   10            55%       0.9dB

L                    20            29%
T                    20           38%       1.2dB

   Dave KH6AQ



On Mon, Mar 1, 2021 at 10:20 PM John <w5jmw@towerfarm.net> wrote:

> Hello all.I currently have a coaxial inv. L.apex at 50ft and rest going
> out at abt 45 degrees.The end is abt 20-30 ft high.It has been a very good
> antenna.I used a l because I did not have the option of 2 masts.I am
> changing a bit.Doing away from vhf/uhf beams.So I have another 50 ft
> mast.They are abt 200ft apart.My question is…Would a tee type vertical be
> better that an L.Yes I could elevate 2 or 3 radials.I am using  a radial
> ground on the inv.L.Thoughts on this please.I am not really concerned about
> matching.Just effenciency.Is a tee better? Thanks,john
>
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