Edge-fed cavity backed patch antennas and arrays

A new edge-fed patch antenna that mitigates spurious radiation issues when thick substrates are used to create the antenna is presented. The radiator can be classified as an edge-fed cavity backed patch. Here, a thin substrate is used to develop the microstrip feed line, thereby ensuring the track widths are small and subsequently decreasing spurious feed radiation. The patch radiator utilises the thick substrate employed in the cavity ensuring reasonable return loss bandwidth can be achieved. A single element and a 2 times 2 array have been designed, fabricated and tested using the proposed technique and it has been shown that significant reduction in pattern distortion and increase in gain can be achieved compared to conventional edge-fed microstrip patch configurations. Because of the thin tracks used to feed the radiators, the new technique is very applicable to large arrays of microstrip patches where the area consumed by the distribution network must be minimised to ensure good radiation performance.