Broadband quarter-wavelength slot array fed by a microstrip line

A 2×2 quarter-wavelength slot array fed by a microstrip line has been presented. By using the quarter-wavelength slots as radiating elements and by properly orienting and placing them with the mutual coupling effects taken into consideration, the physical size of the array can be kept compact. The proposed design has broadband and moderate-gain features and radiates broadside bidirectional patterns.