Design of gap-coupled variations of slotted and shorted 60° Sector microstrip antennas

Various configurations of slotted and shorted 60° Sector microstrip antennas for wider bandwidth are discussed. Slot tunes the spacing between shorted patch TM1/4,1 and TM1/4,0 resonant modes, that gives bandwidth of more than 800 MHz (>60%). The surface current distributions at modified shorted resonant modes were studied. Based on current variations against slot length, formulation in resonant length for shorted modes is proposed. Using proposed formulations frequencies were calculated. They show close agreement with simulated frequencies. The proposed formulations were further used to design slot cut gap-coupled shorted variations at different frequency on thicker air substrate. In all the configurations design procedure achieves wide band response.