Microstrip Array for Reflector Feed Applications

The performance of a small microstrip array for use as a reflector feed is reported. Patch arrays incorporating both coplanar and reduced height electro magnetically coupled feed networks have been investigated. Radiation from the feed network is found to be significant and results in some copolar pattern distortion and cross polarisation of about -20dB and -28dB for the two feed types respectively. Cross polarisation of -28dB is observed from a reflector with the coplanar feed. Array analysis based on a magnetic current model and including feed network radiation and diffraction effects is presented and shows good agreement with measurements.