[amsat-bb] CP antenna from 2 WiFi panels

Greg D. ko6th_greg at hotmail.com
Sun Jun 6 13:15:02 PDT 2010

Hi folks,

Before I start nailing stuff together, I just want to verify what I'm doing...

I want to make a 2.4ghz Right-Hand Circular antenna from two flat panel Wi-Fi antennas.  The idea is to mount them at 90 degrees from each other, with one 1/4 wavelength in front of the other.  Combine the two feeds with a simple Tee (the feeds are of equal length), and into the pre-amp.  Since I'm not transmitting, I'm not too worried about the resulting 25 ohm impedance (or should I be?).

If it matters, the panels are from HyperLink Technologies, their model HG2414P, with a claimed 14dBi gain.

So, the questions:

1.  1/4 wavelength at 2401 mhz is ((3 x 10**8 / 2401 x 10**6) / 4) meters, or about 1.23 inches.  Right?

2.  Most of our 2.4 ghz satellite downlinks seem to be either linear or RHCP, so I'm guessing that RHCP is probably the preferred construction.  (Yes?)  

3.  Looking at the Satellite Experimenter's Handbook (figure 7-10), I believe the panel rotated 90 degrees counter-clockwise as seen from behind the panels should be the one farther out in front, for RHCP.  (Their picture shows clockwise for LHCP.)  Is this correct?


Greg  KO6TH
The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with Hotmail. 

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