Compact active patch antenna

The authors describe an original active patch antenna in which the whole bias circuit, transistor, decoupling circuit and the patch element form a structure which is not bigger than a passive antenna. A compact amplifier circuit composed of a transistor placed on the same face as the radiating patch and a bias circuit etched in the ground plane ensures a high gain and a low loss for the realized antenna. Some precautions have been taken so that the radiation pattern is not affected and the cross polarization level doesn´t have to be raised. This element can be used in active array antennas