X band circular polarisation feeds...

Some experimental circular polarisation feeds for X-band:

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- the simplest and most reliable one is the helix ! ( 43k ) Matching is > 20 dB, ellipticity < 1 dB. Connector used is SMA.

- the AMSAT-OH reference, 45k, horn for P3D. The feed is a recalculated W2IMU design, 65k, with perfect matching and ellipticity.

- and this is a prototype of the flight model horn. The feed uses E & H plane probes, 14k, and a 90 phase shifted splitter to feed it.

- using a servo controlled TVRO rotary joint, 62k, and a delay, 65k, line inside, 62k, the horn waveguide, 78k, ANY polarisation can be achieved !!!

- dimensions for the experimental PTFE delay line used above lie here, 6k. Matching is about 15 dB at worst.

- converting rectangular waveguide TE10 mode directly (6k ) into circular after an idea in Microwave Transmission Circuits.

- some notes on these circular polarisation experiments in Finnish for the benefit of OH hams !

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Updated 06.07.1999