A 90-dB Microstrip Switch on a Plastic Substrate (Correspondence)

A single-pole double-throw (SPDT) microstrip switch has been designed on a plastic (polyolefin) substrate to switch two 10-W CW carriers into a common load over the frequency range 1.7 to 2.3 GHz. No tuning adjustments are used over this 30-percent bandwidth to obtain a 90-dB minimum isolation, a 23-dB minimum return loss, and a 1-dB maximum insertion loss. Units now in production typically have a 0.6-dB insertion loss, a 26-dB return loss, and isolation levels of 105/spl plus mn/5 dB.