Transparent Transmitarray Antenna with Large Aperture for Significant Gain Enhancement in Millimeter-Wave 5G Communication Networks

This paper introduces an optically transparent transmitarray, measuring 720 × 720 mm² at 28.0 GHz. The antenna tackles design challenges related to the full-wave simulation of an electrically-large aperture (67.2 squared wavelengths), utilization of a lossy glass window as a substrate, and the trade-off between transparency and tunable phase range. The transmitarray comprises two glass substrates with three metallic layers, each featuring a 10-μm-width mesh, achieving 70% transmittance. Phase compensation is discretized using 8 unit cell configurations. While simulating the entire structure comprised of 290 × 290 meshed unit cells proves challenging, we use three smaller fully-coated test pieces to observe aperture efficiency variation. After examining the consistency, we predict the gain of the large-aperture configuration. The proposed transparent transmitarray is subsequently fabricated and tested, achieving a measured gain of 37.5 dBi when fed with a quasi-Yagi antenna (with a gain of 7.8 dBi).