Substrate-integrated Fabry-Pérot cavity antenna fed by slot-coupled patch array for directivity enhancement

This paper presents a substrate-integrated Fabry-Pérot cavity (FPC) antenna fed by a slot-coupled patch array. The patch array contributes to a homogeneous excitation on antenna aperture and achieves further improvement on directivity. The effects of array´s interelement distance on antenna´s radiation characteristics are investigated to show a different trend with that of arrays in air-filled FPC antennas. Besides, the slot-coupled structure is introduced to feed the patch array to prevent the feeding network from radiating in the cavity. For verification, substrate-integrated FPC antennas fed with 1 and 4 patches operating in X-band are manufactured. The measurement shows that the antenna fed by 4 patches presents a maximum gain of 15.5 dBi at 10.0 GHz, which is 1.5 dB more than antenna fed by 1 patch.