[eagle] Re: Another idea on phased array configuration

John B. Stephensen kd6ozh at comcast.net
Sat Apr 28 23:21:12 PDT 2007


The spreadsheet distributed early last year shows a 9 degree squint angle at 
the leading and trailing horizons at apogee. An antenna with an 18 degree 
half-power beamwidth has a gain of 41000/(HPBW^2) = 127 = 21 dBi. It would 
be best to illuminate the earth with a loss of only 1 dB at the edges and 
the -1 dB beamwidth is going to be 2/3 or less of the -3 dB beamwidth. The 
gain should then be adjusted by 4/9 or 3.5 dB less. This would be 17.5 dBi.

73,

John
KD6OZH

----- Original Message ----- 
From: "Matt Ettus" <matt at ettus.com>
To: "John B. Stephensen" <kd6ozh at comcast.net>
Cc: "Louis McFadin" <w5did at amsat.org>; "Robert McGwier"
<rwmcgwier at gmail.com>; "AMSAT Eagle" <Eagle at amsat.org>; <K3IO at verizon.net>
Sent: Saturday, April 28, 2007 19:57 UTC
Subject: Re: [eagle] Re: Another idea on phased array configuration


>
> John B. Stephensen wrote:
>> Since the generated beam needs to cover the entire earth from a maxmum of
>> 35,000 km in alttude, the beam can't be made very narrow. I don't think
>> that all 36 or 43 elements ever need to be on at one time. Many could be
>> held in reserve.
>
>
> Where do you come up with this?  What sort of analysis?
>
> Matt
>
>



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