A microstrip multiple beam forming lens

A recent paper1 has described the design and performance of a waveguide-fed parallel plate lens which provides five beams from a sixteen element antenna array, with sidelobes ¿ ¿ 20 dB and beam crossovers ¿ ¿ 10dB, in the frequency band 8¿12 GHz. A microstrip version of this lens has been designed, constructed and tested, with the addition of a beam port overlap network to now provide nine beams with crossovers ¿ ¿ 2 dB. Fair performance is achieved at midband, but internal reflections are found to limit the bandwidth of the microstrip lens design.