A design method of microstrip directional coupler with multi-elements compensation

A design method of microstrip directional coupler with multi-elements is presented. The theory, design and measurements are given. In order to obtain high directivity, the two-, three- and four-compensated capacitors are added to realize capacitive compensation. The experimental results show that the microstrip directional coupler with multi-compensated capacitors have the better isolation compared with the conventional directional coupler at the frequency range from 2.5GHz to 3.5GHz and the couplers with three- and four-compensated capacitors have the wider frequency response compared with the coupler with two-compensated capacitors. The experimental results validate the design method well.