A Wideband Dual-Linearly Polarized Folded ME-Dipole Transmitarray Antenna With Low H/F Ratio
Bing Jie Xiang, Kwai-Man Luk
Abstract
A wideband dual-linearly polarized (dual LP) low-profile transmitarray (TA) antenna is proposed based on a novel folded scheme and a magnetoelectric (ME) dipole structure. Introducing a phase-gradient reflective surface (PGRS) in the folded scheme, the space sandwiched by the TA surface and the feed is reduced by two-third, leading to the low-profile structure. To validate this scheme, a center-fed ME dipole antenna is proposed and extended to be a dual-LP TA element with independently controlled 1-bit resolution for the two orthogonal linear polarizations. On the other hand, the PGRS element is composed of cross-dipole and ME dipole structures, which can provide over 360° phase shift range and generate a focus and work as the feeding source. To verify its feasibility, a prototype operating at 26 GHz is simulated, processed, and tested. The measured results show that the proposed folded TA antenna can achieve a peak gain of 23 dBi, a peak aperture efficiency of 21%, and a 3-dB gain bandwidth of 26% for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x$ </tex-math></inline-formula> -polarization. The corresponding results for the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$y$ </tex-math></inline-formula> -polarization are 23 dBi, 21%, and 28%, respectively. This competitive performance together with merits, such as compact size, low cost, and low profile, enable the proposed prototype to be a promising candidate for the future millimeter-wave wireless communications.