High-Gain Patch Antenna Based on Cylindrically Projected EBG Planes

One kind of artificial ground consisting of nonperiodic electromagnetic band gap (EBG) structures with adjustable off-center vias is first proposed. According to the projection equivalence, an artificial plane similarly equivalent to a cylindrical metal reflector can be constructed by proper deployment of the vias in the EBG plane, which can strongly focus electromagnetic waves to realize an extremely directive antenna with a high gain. For demonstration, two X-band high-gain differential-fed patch antennas using the proposed EBG planes are accordingly designed. The simulated and measured results indicate high gains of 14.1 and 11.7 dBi are, respectively, achieved for these two antennas, over 1-2 dB improvement than the antennas based on periodic mushroom EBG structures, thus achieving higher aperture efficiencies of 88% and 107.2%; meanwhile, the gain variations are less than 2 dB in the whole frequency band of interest. Compared with a conventional 2x2 patch antenna array, the proposed antenna can not only avoid extra feeding network, but also exhibits a higher gain and a higher aperture efficiency within a much wider working band.