Synthesis procedure for active integrated radiating elements

This letter demonstrates a technique for the synthesis of a new integrated active radiating element topology. The approach adopted uses a microwave MESFET operating in large signal mode as the active device in an oscillator configuration. The oscillator has as its parallel feedback element and load element a microstrip patch antenna. The synthesis approach developed in this paper uses numerical optimisation to find the optimum terminal voltages for a given MESFET at a specified frequency. A set of explicit equations is presented in terms of these optimum terminal voltages. These allow the active radiating element terminations to be realised analytically. An NE71000 chip is used as the active device in the active radiating element circuit. Construction is on RT Duriod 5880 and the circuit operated at 10.2 GHz with 30 mW power delivered to the antenna.