A Planar Low-Profile Transverse Permittivity Gradient Phase Correcting Structure for Electromagnetic Bandgap Resonator Antennas

This paper presents a planar and a low profile phase correcting structure (PCS) for electromagnetic bandgap resonator antennas (ERAs). The PCS improves phase uniformity of the electric near-field of the ERA. It achieves phase uniformity by providing custom phase delays, to the electric field propagating through it, so that nearly uniform phase is achieved at the output. The phase delays are implemented using transverse permittivity gradient (TPG) in the PCS. The permittivity values are selected according to the non-uniformity in the phase distribution of the electric field radiated by the ERA. The TPG PCS is placed in the near-field of the ERA. It has a planar profile and better radiation performance in contrast to the dielectric PCSs proposed earlier.