A Transmission-Type Ultralow-Profile Fabry-Perot Cavity Antenna with Wide Directivity Bandwidth Using Anisotropic PRS and Isotropic AMC

Fabry-Perot-Cavity (FPC) antenna frees the feeding networks of the traditional microstrip arrays with its cavity-fed antenna configuration, but its half-wavelength cavity height will reversely restrict its application in the lower operating bands. Although several cavity-compressed FPCs have been reported to unlock this restriction, it still suffers from ultra-narrow -3 dB directivity bandwidth due to the unsatisfied inter-cavity phase resonance relationship resulting from the finite cavity resonance modes. We target this issue and propose a novel methodology to implement an FPC antenna featured in broadband high gain and ultralow cavity profiles. The proposed FPC antenna contains an anisotropic partially reflective surface (PRS) providing a multi-mode reflection phase, an isotropic artificial-magnetic-conductor loaded ground offering phase compensation, and an inter-cavity feed source. The multi-mode reflection phase of the anisotropic PRS will assist in constructing the multi-mode FP cavity which has a wide phase resonance bandwidth. With a wide-band satisfied phase relationship, the wide-band directivity bandwidth can be achieved. The proposed FPC antenna realizes a 15.3% -3 dB directivity bandwidth under a 0.3 mm cavity height.