Three‐dimensional circular patch antenna under TM 02 mode with improved impedance matching

Abstract

A circular patch antenna under TM 02 mode with improved impedance matching is proposed by adopting 3D architecture. It is known that the TM 02 mode of circular patch can generate omnidirectional radiation, but its input resistance reaches maximum at centre point. In this context, impedance matching is difficult to be achieved and the feeding probe is often supposed to be placed a distance away from the centre, inevitably destroying the symmetry of radiation pattern. Without introducing pins or slots, a direct strategy is here employed where the circular patch is folded to form a concave at its centre. It is found that the input resistance can be effectively reduced with increasing depth of concave since the described concave serves as vertical electric wall in cavity and weakens the electric field in the region between centre and ground. By using electroplate technology based on plastics, a 3D antenna prototype is fabricated and measured to validate the proposed methodology.