A Ka-band one-dimensional beam scanning leaky-wave antenna based on liquid crystal

Abstract

Fixed frequency beam-scanning leaky-wave antennas have been a focus of attention for many scholars in recent years, and numerous related results have been obtained. However, these antennas suffer from several issues such as small beam-scanning range, low gain, and unsatisfactory impedance matching. To address these problems, this paper proposes a microstrip line (ML) antenna unit based on liquid crystal (LC) materials etched Complementary Split Ring Resonator (CSRR). In a first-of-its-kind approach, the substrate integrated waveguide (SIW) structure and the ML transmission structure are combined to present the SIW-ML transmission structure. The antenna operates in the Ka-band with excellent resonance characteristics at 34.7 GHz, and the S11 parameters are below − 13 dB in the frequency range of 30–40 GHz, indicating outstanding impedance matching. By arranging 56 antenna units, a periodic leaky-wave antenna is created, enabling fixed-frequency beam-scanning at 34.7 GHz. Experimental results show that the antenna can achieve scanning of angles between − 53° and + 60° with a gain of up to 12.63 dB. Once single-beam scanning is achieved, a method combining LC and discrete amplitude weighting technique, as well as multi-beam theory, is proposed for multi-beam study. Experimental results reveal that the designed 56-unit beam-scanning antenna can effectively realize beam scanning in two directions.

MCML-BF: A Metal-Column Embedded Microstrip Line Transmission Structure with Bias Feeders for Beam-Scanning Leakage Antenna Design

“…However, this structure has the disadvantages of a complicated fabrication process and poor flexibility in unit configuration. To combine the advantages of the two structures, we propose a metal-column embedded microstrip line (MCML) transmission structure based on the traditional ML structure by borrowing the structural characteristics, i.e., by placing two rows of metal posts in the SIW [ 45 ]. It is worth noting that, unlike SIW, the metal columns of the MCML structure do not play the role of connecting the upper and lower metal layers.…”

“…This design achieved a beam scanning range from −45° to 51°, with a maximum gain exceeding 9 dBi and a reflection coefficient below −10 dB [ 44 ]. A microstrip line leakage antenna based on the etched complementary open resonant ring of LC materials is proposed in [ 45 ]. The antenna works in the Ka-band, and by arranging 56 antenna units to form a periodic leakage antenna, it can achieve a scanning angle between −53° and 60° at 34.7 GHz, and the gain can reach 12.63 dB.…”

“…Current research on beam scanning leakage antennas based on LC materials has achieved an excellent level; these advances have the advantages of wide beam scanning range, high gain, and high-frequency band. The authors of [ 45 ] achieved excellent beam scanning performance. Low attenuation loss transmission of electromagnetic waves was accomplished by embedding two rows of metal columns in the medium on the basis of a traditional ML transmission structure.…”