  We present the design and test results of a compact C-band orthomode
transducer which comprises four rectangular probes orthogonally arranged in a
circular waveguide, designed to work in the WG13 band. Measurements of the
system in the frequency range 4.64 GHz to 7.05 GHz agree very well with
simulation results and show a cross-polarisation level below -58 dB, a return
loss of about -20 dB, and an insertion loss difference of less than 0.18 dB
between the orthogonal polarisation modes across the full waveguide band.

Astrophysics