Zhe Xiong

A novel microstrip magnetic-current electronically steerable leaky-wave antenna (LWA) is proposed, capable of wide-angle two-dimensional (2-D) beam scanning over a broad band. The radiation mechanism is realized through a simple microstrip magnetic-current array. To enable dynamic beam control, each magnetic-current controlling unit is integrated with a PIN diode to allow operating state switching. Holographic method is employed to achieve real-time 2-D beam scanning in both azimuth and elevation planes. Besides, conventional LWAs often suffer from beam squint, which degrades the stability of signal strength in specific directions in the bandwidth. To address this issue, a center-fed substrate integrated waveguide is developed for the excitation of the microstrip magnetic-current array. This architecture effectively suppresses beam squint and stabilizes the gain across the signal bandwidth. A prototype is fabricated and measured, demonstrating 2-D beam scanning from 4.5 to 5.6 GHz. The antenna achieves a peak realized gain of 15.66dBi at 5.0 GHz. Measured gain drops are constrained to 3.90dB for scans up to ±50° and 5.18dB up to ±60°, with an average reduction of 3.75dB toward the band edges. Measured results show a good agreement with the simulated ones, validating the effectiveness of the proposed design. Due to its simple structure, low profile, low cost and lightweight, the antenna is suited for beam-scanning communication scenarios.

In this paper, a dual-polarized (DP) fixed-frequency beam-scanning leaky-wave antenna (LWA) is presented. Operating from 24.5 to 27.5 GHz, the LWA consists of a vertically polarized (VP) patch array, a horizontally polarized (HP) printed dipole array, and a dual-channel gap waveguide (GW) that provides traveling-wave excitation. The VP patch array, located at the center of the antenna aperture, contains 80 slot-excited patches. The HP dipole array is divided into two subarrays distributed on both sides of the antenna aperture and is excited by slot-coupled microstrip lines. The VP and HP arrays are independent, enabling simultaneous control of both polarization beams. Due to the low profile of the printed dipole, the radiation aperture of the antenna can be fully utilized, providing the ability to expand in two dimensions. To achieve fixed-frequency beam scanning, each antenna unit has a 1-bit amplitude modulation capability, realized by electrically controlling the PIN diode. A dual-channel GW capable of transmitting both TE01 and TE10 modes is designed, and the stacked architecture makes it suitable for a compact DP antenna. Holographic method is employed to realize the beam scanning. Simulated and measured results verify that the proposed antenna can achieve fixed-frequency, wide-angle, and quasi-continuous beam scanning.

This article presents a fixed-frequency beam-scanning leaky-wave antenna (LWA) that relies on phase control to achieve beam steering and reconfigurable polarization in millimeter-wave (mm-wave) band. The entire antenna is comprised of an air-filled groove gap waveguide and 64 reconfigurable polarization perturbation unit, facilitating the transition between left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP). Each unit is equipped with four PIN diodes, enabling the switching of polarization states and radiated phase states. Through simulation and experimental verification, the designed LWA demonstrates a large scanning range, covering from backward -45° to forward 50° in both LHCP and RHCP. The measured peak realized gain attains 15.4dBic for LHCP and 15.6dBic for RHCP. Additionally, the axis ratios of majority scanning beams remain below 3dB, showing good circular polarization characteristics. The polarization reconfigurable LWA has potentials in the field of mm-wave wireless communication.

In this letter, a hexa-polarization reconfigurable fixed-frequency beam scanning leaky-wave antenna (LWA) operating in the millimeter-wave band is developed. Two parallel gap waveguides (GWs) are used as the basic transmission structure, and wide serrated ridges are adopted to produce quasi-TEM mode and slow-wave transmission in the GWs. A square patch array excited by the GWs is designed to generate radiation with desired polarization. A control structure loaded with PIN diode is applied to tune the working state of each patch unit. Then based on the holographic theory, the hologram on the antenna aperture can be manipulated by controlling the states of all the patch elements. In this way, six polarizations can be obtained (±45° linear polarizations, horizontal polarization, vertical polarization, left-hand circular polarization and right-hand circular polarization), and independent fixed-frequency beam scanning for each polarization can be achieved. In the measurement, a beam-scanning range of 100° is realized for each polarization state, and the property of two circular polarizations is also verified by the measured axial ratios. Therefore, this LWA shows potential in the millimeter-wave applications that demand polarization agility and fixed-frequency beam scanning.