Monopolar square patch antennas with wideband operation

The design of a wideband patch antenna with monopole-like conical radiation patterns is presented. The antenna has a square patch that is shorted to the ground plane through two shorting walls and is excited by a top-loaded coaxial feed centred below the square patch. Several prototypes with various antenna heights are implemented and measured. A prototype with impedance bandwidth of about 50% is achieved when its height is less than 0.09 free-space wavelengths.