Low-Profile High-Gain and Wide-Angle Beam Scanning Phased Transmitarray Antennas

Peng-Yu Feng,Xiao-Han Chen,Shiwen Yang,Shi-Wei Qu

doi:10.1109/access.2020.2974066

Abstract

Combining the inherent multiple beam capabilities of transmitarray antennas (TAAs) and the flexible fields launched by phased array antennas (PAAs), PAA-fed TAAs are proposed in this paper for high-gain and wide-angle beam scanning in millimeter-wave (MMW) band. After thoroughly analyzing the operating mechanisms of the PAA-fed TAAs, a divisionally multi-focal method is proposed to deploy the TAA elements, which can be better adapted to the PAA feed whereby the scanning performances are improved. Subsequently, two PAA-fed TAAs with feeding distance-to-diameter ratios (H/Ds) of mere 0.28 are numerically demonstrated at 39 GHz, wherein both TAAs are composed of the square subwavelength low-pass elements and the cavity-backed bowtie patch antenna is identified as the PAA feed element. Simulated results show that the first design example achieves a conical beam steering over ±30° with a 30.9 dBi peak gain and gain drop below 2.1 dB. The second design can scan across ±50°/±10° along the E/H planes, respectively, together with the gain losses of 3.3 and 1.6 dB from the peak value of 31.1 dBi. Finally, the first design case is fabricated and measured for experimental verification purpose, whose measured results agree reasonably well with the simulated ones.

Highlights

Millimeter-wave (MMW) communication systems have attracted growing research attention due to their wide available frequency spectrum
Since the phased array antennas (PAAs) feed is located between the transmitarray antennas (TAAs) and its real focal spot, dispersed energy distributions are produced across the PAA feed aperture, successfully activating more feed elements simultaneously for any given desired scan direction
The scanning range and gain drop are the most pivotal criteria to gauge the performances of wide-angle beam scanning TAAs, which are mainly determined by the phase mismatching between the required phase compensations and those provided by the available TAA elements at each scan angle

Summary

INTRODUCTION

Millimeter-wave (MMW) communication systems have attracted growing research attention due to their wide available frequency spectrum. Combining the space-fed mechanism of traditional lens antennas and the operations of PAAs, transmitarray antennas (TAAs) are emerging as an attractively low-cost candidate of high-gain beam scanning MMW array antennas. Because the TAA phase distribution in [14] is determined by traditional singlefocal method, obvious scan loss up to 3.7 dB is suffered according to the measured results Inspired by these works, PAA-fed TAAs aiming at highgain and wide-angle two-dimensional (2-D) beam scanning are proposed in this paper in MMW band. Since the PAA feed is located between the TAA and its real focal spot, dispersed energy distributions are produced across the PAA feed aperture, successfully activating more feed elements simultaneously for any given desired scan direction Such a phenomenon enables remarkable EIRP enhancements against traditional switched beam TAA in the transmitting mode. Less susceptible to electromagnetic interference, benefiting the simplification of the RF front-end circuits

DIVISIONALLY MULTI-FOCAL METHOD

CONCLUSION