Wideband beam-steerable configuration of metasurface loaded slot antenna

Abstract

In this article, a wideband two dimensional (2D) beam‐steerable antenna structure is presented. The proposed structure is based on a radially gradient hybrid metasurface (RGHMS) illuminated through a slot antenna. The half aperture of the RGHMS comprises of a gradient phase profile topology, while its other half aperture consists of a constant phase profile configuration. The slot antenna possessing the bidirectional radiation pattern is printed on a relatively thin substrate, which operates over a wide bandwidth of 1420 MHz (15.10%). The placement of RGHMS tilts the main beam of slot antenna by 15° away from normal direction. Further, in‐plane movement of MS provides beam steering in both elevation and azimuth planes, with a conical region of an apex angle of 30°. Apart from the beam steering capability, the placement of RGHMS in front of slot antenna also enhances the overall bandwidth and gain by 360 MHz and 5 dB, respectively. Thus, a wide band beam steering configuration with the impedance bandwidth of 1780 MHz (18.85%) is obtained. In order to investigate the frequency dependent beam tilting capability of the RGHMS in the elevation plane, a detailed analysis is carried out using the principle of refraction.

A compact configuration of semicircular metasurface loaded slot antenna for beam steering application

“…For showing the potential of the proposed beam steering configuration in the real scenario, the measurement is carried out while considering one of the SCRGMs with slot antenna. In summary, as compared to the previous work, the proposed antenna configuration is more compact and is providing large range for elevation beam scanning in both of the upper and the lower hemispheres of the slot antenna, which is the first structure of its kind. The proposed antenna is designed to operate in the frequency range starting from 9.3 to 9.85 GHz.…”

“…The main emphasis in refs. was to achieve beam steering in both azimuth and elevation planes, which basically requires quite rotationally symmetric phase distribution of the corresponding electric field component. It was observed that at an approximate height of 0.50 λ 0 from the aperture of the antenna, the nonzero E y component shows quite rotationally symmetric phase distribution for this configuration as clearly seen in Figure A.…”

“…Hence, the radially gradient hybrid metasurface could be safely placed at an approximate height of 0.50 λ 0 from the aperture of antenna to facilitate beam steering in both azimuth and elevation planes in refs. . However, the main aim of this work is to achieve quite compact configuration to achieve beam steering in the elevation plane only, using the proposed semicircular radially gradient hybrid metasurface (SCRGM).…”

“…To achieve compactness in the beam steering structures, the intermediate planar lens has been eliminated in refs. . In these structures, a radially gradient hybrid metasurface (RGHMS) was directly illuminated through the spherical wavefront of the source element and hence a compact beam steerable configuration has been achieved.…”

“…It was investigated that at an approximate height of 0.50 λ 0 from the aperture of antenna, the nonzero E y component of the antenna shows quite rotationally symmetric phase distribution. Hence, the RGHMS with the approximate aperture size of 4.5 λ 0 2 was safely placed at an approximate height of 0.50 λ 0 from the aperture of antenna to facilitate beam steering in both the azimuth and elevation planes . It was later realized that using slightly asymmetric phase distribution of the E y component of antenna in its close proximity, the more compact configuration with better beam scanning range in the elevation plane can be obtained while tolerating beam steering in the horizontal plane.…”