A software configurable coupler with programmable coupling coefficient

Abstract

A novel microstrip parallel coupler with tunable coupling coefficient is proposed. Two varactors are placed on microstrip parallel-coupled lines to tune the coupling coefficient. With proper combinations of the capacitances of two varactors, the coupling coefficient can be tuned from 10 dB to 6 dB with good return loss and directivity. By using the Labview program and data acquisition component, at software configurable coupler is implemented. This software configurable coupler will be useful in microwave instrumentation.