[TowerTalk] 80m 3element

[Jim Lux]

SNR usually applies to a link (i.e. transmitter to receiver)

Are you assuming that the noise distribution is uniform around the antenna?
Then the SNR would be the incoming signal power density, times the effective
aperture (which is related to the directivity, etc.) , divided by the noise
power.  Given, however, that for HF frequencies, atmospheric and
environmental noise dominates over receiver noise, and those external noise
sources tend to be nonuniformly distributed, you might need a more
sophisticated approach.

VOACAP (which is free) can take an antenna pattern and calculate SNR for a
particular link (or links) under various assumptions of environmental noise,
transmitted signal strength, SSN, time of year, etc.  However, they're just
statistical forecasts, and I don't think they take into account noise
distribution, just noise environment in the bulk sense (i.e. Rural,
Suburban, Urban, etc.) in accordance with ITU/CCIR type recommendations.

Several antenna modeling programs (4nec2, for instance) can generate the
file in the format needed by VOACAP.

Jim Lux, W6RMK

----- Original Message -----
From: "DanB" <longterm at chatusa.com>
To: "tower" <towertalk at contesting.com>
Sent: Sunday, February 23, 2003 4:12 PM
Subject: [TowerTalk] 80m 3element


> Looking for a program that can  calculate  signal to noise for 3 element
> on 80M beam. I am using EZNEC now.
>
> NN7J
>
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