Frequency agile annular ring microstrip antenna loaded with IMPATT diode

A theoretical investigation of IMPATT diode integrated annular ring microstrip antenna is proposed. In which the resonance frequency is controllable by means of bias voltage of IMPATT diode without altering the radii of annular ring. The investigations based on cavity model are carried out for the various feed location and reverse bias voltage and maximum frequency agility of 10 MHz is achieved with bias voltage.