[amsat-bb] Arecibo on 432 MHz Moon Bounce (some calculations)

i8cvs domenico.i8cvs at tin.it
Fri May 7 14:58:05 PDT 2010

Hi All,

I have received an email from Daniel Esteban LU2DDU informing me that
about the Arecibo radiotelescope he was in touch with Victor KP4PQ in order
to get from him more details about the feed line running from the operating
site up to the feed.

Victor says to Daniel that for 432.045 MHz they were using an existing wave
guide with the larger side 23" high ( 58 cm ) and 1500 ' long ( about 457
meters long) with a loss of 1 to 1.2 dB i.e. about 1.32 time in power ratio
at 432 MHz

Please note that the size of the above wave guide can be compared to the air
duct of an air conditioning system normally used into a big industrial shed.

Considering that the power amplifier was running at best 350 watt it follows
that the power reaching the feed was 350 / 1.32 = 265 watt

Since the gain of the Arecibo dish is 60 dB or 1000000 time in power ratio
it follows that the Arecibo EIRP was 265 MW

Tanks to Daniel LU2DDU and Victor KP4PQ for the above information.

Best 73" de

i8CVS Domenico

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