A theoretical investigation of the circular printed circuit antenna

A circular, conducting disc above a ground plane is analyzed theoretically to provide a design procedure for practical antennas. The fields within the cavity formed by the disc and the ground plane are calculated using the conditions of resonance for a circular resonant structure . A parallel plate antenna is used as a mathematical model. The far fields are found both by using the surface currents on the discs and also from the fields at the aperture between the disc and the ground plane. The two methods result in essentially identical results for electrically thin structures. The total radiated power and the power losses are found and approximate results are also given for the case with the cavity filled with a dielectric material.