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435 MHz CP antenna



Tracy K7KCS:

I would like recommendations on an uplink 70cm CIRCULAR polarized antenna for AO-40 (or linear if I don't need circular . . you tell me).   My available power is about 30 watts.  I'd prefer to purchase not build.

Wayne replies:

I would recommend the M-squared 436CP30 antenna.  It is circular polarized with 30 elements (15 on each plane) on a 9.75 foot boom.  It's small enough to be pointed with TV rotors.  For AO40 you probably don't need the polarity switching upgrade.  That just adds cost and decreases reliability.

You could also try to find a used KLM circular polarized antenna.  KLM is out of business, but they made great antennas.  The most popular KLM 435 MHz antenna had 40 elements on a very long (19 foot?) boom, which is inconveniently long in my opinion.

30 watts (with low cable loss) to a 436CP30 is probably barely enough power to "meet LEILA" when the off-pointing angle is low.  Times Microwave LMR-400 is a good low-loss cable for short-to-medium cable runs.  It has about the same loss as Belden 9913, but it more water-resistant.

Wayne Estes W9AE
Mundelein, IL, USA
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