Metantennas: From Patch Antennas to Metasurface Mosaic Antennas (Invited Paper)

“Microstrip Patch Antenna” has been widely and intensively investigated and applied in wireless system in the past five decades. To alleviate the narrow bandwidth of the antennas, many techniques have been proposed. One of them is to reduce the Q-factor for increasing the radiation from the antenna. The bandwidth is enhanced from 1% to 10% by increasing the thickness from 1% to 6% times wavelength and removing the dense dielectric of substrate supporting the radiating patch. Furthermore, U-slotted patch has been proposed to introduce additional modes to further increase the bandwidth to 30 ~ 40%. L-probe is another wideband feeding structure to perfectly excite the broadband suspended plate antenna. The both are invented in 1990s by K. F. Lee and K. M. Luk. Recently, a new type of slotted patch antennas like an array of mushroom and later a mosaic has been proposed for bandwidth enhancement in terms of impedance and radiation patterns. The mosaic antenna is still printed onto a piece of full-dielectric PCB. The grid-slots on the patch significantly increase the radiation and change the dispersion response of patch antenna acting as a metasurface. With an aperture coupling feeding structure, the two adjacent modes are well excited and generate identical radiation performance. More and more variations of the metasurface mosaic antenna have been proposed and developed for performance enhancement and new functionalities.