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Re: Helix feeds revisited



Thanks.. this is great.  All someone has to do now is take a protractor to 
the dish they have that is in question and match the appropriate 10 dB 
points in your table to the measured angle, and they would have an adequate 
feed.  Would you mind if I HTMLed this (someday-- I'm very busy for the next 
couple of weeks/months!!) and put it on my site with the Helix calculator?

Excellent work!

Fred W0FMS


>From: "Howard Long" <howard@howardlong.com>
>To: <amsat-bb@AMSAT.Org>
>Subject: [amsat-bb] Helix feeds revisited
>Date: Wed, 18 Jul 2001 17:44:41 +0100
>
>Folks
>
>I re-modelled the G3RUH helix feed from scratch with a far more accurate
>representation than my first attempt and came up with some slightly
>different results.
>
>  Turns  Gain (dBi) F/B (dB)  3dB Beamwidth  10dB Beamwidth
>   2.25      9.6      13.3        61.2            116
>   2.75     10.0      14.8        57.2            107
>   3.25     10.6      14.6        52.8             95
>   3.75     11.0      13.2        50.8             88
>   4.25     11.2      13.3        49.7             85
>   4.75     11.4      15.0        48.1             81
>   5.25     11.8      15.7        46.0             78
>   5.75     12.0      14.2        44.3             74
>   6.25     12.2      13.8        43.3             71
>   6.75     12.5      15.4        42.1             69
>   7.25     12.7      16.8        40.6             66
>   7.75     12.9      15.5        39.4             64
>
>Beamwidths are in degrees.
>
>73 Howard G6LVB
>
>----
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