A 90 DB Microstrip Switch on a Plastic Substrate

A SPDT microstrip switch has been designed on a plastic (polyolefin) substrate to switch two 10 watt cw carriers into a common load over the frequency range 1.7 to 2.3 GHz. No tuning adjustments are used over this 30% bandwidth to obtain a 90 dB minimum isolation, a 23 dB minimum return loss, and a one dB maximum insertion loss. Units now in production typically have a .6 dB insertion loss, a 26 dB return loss and isolation levels of 105/spl plusmn/5 dB.