Low loss ferroelectric microwave switch

A low loss ferroelectric microwave switch has been developed recently for operation at L-band frequencies. The switch is constructed in strip transmission line using (Ba-Sr)TiO3as the active element. It is capable of switching in less than 0.1 usec and provides isolation in excess of 20 db with an insertion loss of less than 0.7 db over a band of 20 Mc. The active element is a ferroelectric variable capacitor, which is controlled by a bias voltage of 600-800 volts in its present form. In pulse switching applications, the switch incorporates a blocking oscillator to provide fast voltage pulses of proper duration. When used as a DPDT switch, the device is placed in one output arm of a circulator. The power handling capabilities of the switch have not been assessed; however the active element is polycrystalline ceramic and is therefore not susceptible to burnout.