[eagle] Re: Another idea on phased array configuration
matt at ettus.com
Sat Apr 28 23:57:05 PDT 2007
So what? We can have, and were planning on having, an 18dB gain array.
That doesn't mean we need to turn any elements off.
John B. Stephensen wrote:
> 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.
> ----- 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?
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