A Low-Profile Wideband Patch Antenna With Modified Parasitic Mushroom Structures on Nonperiodic AMC

In this letter, a low-profile wideband antenna working around 28 GHz based on the nonperiodic artificial magnetic conductor (AMC) is presented. Mushroom structures are loaded with central patch to broaden bandwidth. Four vias at edges are added to suppress cross polarization. A parasitically coupled structure is integrated with AMC. The nonperiodic AMC, central patch, and parasitic structures create five resonant modes together. Characteristic mode analysis and effective relative permittivity of AMC are calculated to explain the bandwidth broadening mechanism. A prototype is fabricated to verify the design concept. The measured result shows wide impedance bandwidth of 33% (24.05-33.52 GHz) and high peak gain of 10.24 dBi.