[amsat-bb] Phased Vertical Array for PACSATS?

[Bob Bruninga <bruninga@xxxxxxxxxxxxx>]

I'm working on a 3 element car-roof vertical phased array for mobile
9600 Baud PACSAT operations.  Mine uses 3 quarterwave whips on the roof
plane as opposed to the similar 4 antenna J-Pole array published in this
months AMSAT journal.  He claims 9 db for his 4 element but doesnt say if
this is dBi or dBd.  Best I can figure, my gain should be around 8 dBi

Cant find a definitive answer in the ARRL Antenna book.  Does anyone care
to model this antenna before I get too far with this?  For 3 verticals,
what is the opitimum spacing for gain?  1/4 wavelength? corner-to-corner
or 1/4 wavelength Apex-to-base?

My 3 whip antenna tonight did about 3 dB worse than a 3 element beam on
several comparitive passes...  So although I had VSWR down to 1.0, the
beam pattern must not be optimum... for my 1/4 spacing.

de WB4APR, Bob


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