Microstar, Inc.
Broadband Feeds

These feeds provide broadband dual-polarization illumination for reflector antennas with f/D ratio between 0.35 and 0.5.

Above 6 GHz, full waveguide bandwidth is provided using a waveguide orthomode coupler with a scalar horn for dual linear polarization, or with the addition of a multi-pin polarizer if dual circular polarization is required. The VSWR is 1.5 maximum. The isolation for dual linear feeds is greater than 30 dB (40 dB can be provided at extra cost). The axial ratio for dual CP feeds is less than 3 dB, and less than 2 dB over most of the band. Waveguide-to-coax transitions can be provided if coaxial outputs are required.

The 4-6 GHz feed uses a quad-ridge transition with a scalar horn, plus a polarizer if dual CP is required. The 2-4 GHz feed uses a square quad-ridge radiator with the addition of a 90 degree coupler if dual CP is required. For these two feed types the VSWR is 2:1 max, the dual-linear isolation is 30 dB min, and the dual CP axial ratio is 3 dB max.

For the Dual Log Periodics at lower frequencies the VSWR is 2:1 max, the dual linear isolation is 25 dB min, and the dual CP axial ratio is 3 dB max.

4 - 6 GHz Dual CP Feed

4 - 6 GHz Dual CP Feed

1 - 2 GHz Dual Linear Feed

1 - 2 GHz Dual Linear Feed

2 - 4 GHz Dual CP Feed

2 - 4 GHz Dual CP Feed