- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
A Wideband, Single-Layer Reflectarray Exploiting A Polarization Rotating Unit Cell
摘要： We present a new technique for designing wideband, single-layer reflectarray antennas. The proposed reflectarray exploits a wideband, polarization rotating unit cell that rotates the polarization of the reflected wave with respect to that of the incident wave by 90?. This unit cell and its mirror image were used as 1-bit spatial phase shifters capable of providing a 0?/180? phase shift over a wide bandwidth of 5.4-12.7 GHz. Using this, a reflectarray antenna with 1-bit phase quantization was designed to operate at X band with aperture dimensions of 28.8 cm × 28.8 cm and a focal length of 30 cm. A prototype of the proposed reflectarray was fabricated and characterized using a spherical near-field measurement system. We determined the antenna’s 3 dB gain bandwidth to be approximately 37.4% with a maximum realized gain of 24.2 dBi. Over its entire band of operation, the polarization purity of the antenna remains better than 13 dB and side-lobe levels of better than 12 dB were achieved.
关键词： periodic structures,Reflectarray antennas,polarization rotation,antenna arrays
更新于2025-09-10 09:29:36
-
A 400-GHz Wideband High-Gain Quartz-Based Single-Layered Folded Reflectarray Antenna for Terahertz Applications
摘要： Compact high-gain antennas are highly desired in the high speed terahertz (THz) wireless system, especially for the space limited application such as the high speed inter-link inside the high density wireless communication base station. To this end, a 400-GHz folded reflectarray (FRA) antenna with high gain, high aperture efficiency and compact profile is proposed in this paper. It is composed of a feed source, a single-layered reflectarray using a lithography process on quartz, and a wire-grid polarizer implemented by the printed-circuit-board (PCB) technology. A 3-D printed fixture is used to assemble all parts together. In order to design accurately the THz electromagnetic properties of the supporting dielectric materials are extracted by using a THz time-domain spectrometer system. Then, a single-layered phasing element, made up of a pair of orthogonally I-shaped structures with an open square ring, is proposed and designed based on the extracted material characteristics. Both phase compensation and polarization conversion can be realized by the proposed unit cell. A reflectarray is designed by using the proposed phasing element with the conventional array synthesizing theory, and a THz grid polarizer is designed with strips on a 0.127 mm Taconic TLY-5 substrate. The THz grid is placed in front of the THz feed and the reflectarray, which is fully reflective to the feed and transparent to the reflectarray. All components of the FRA antenna have been fabricated and assembled. Experiments show that the FRA prototype has a peak gain of 33.66 dBi at 400 GHz with an aperture efficiency of 33.65%, and a 3-dB gain bandwidth of 16% (357-421 GHz).
关键词： terahertz,3-D printing,high-gain,material characteristics,quartz substrate,single-layer,Folded reflectarray antenna,THz time-domain spectrometer
更新于2025-09-10 09:29:36
-
[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - A Sub-Wavelength Reflectarray Element Based on Minkowski Fractal Loop
摘要： A novel reflectarray element consists of one Minkowski fractal loop in combination of a square loop is proposed. The size of the element is two fifth of a wavelength of the working frequency of 5.8 GHz. The proposed element offers a slope value of 20°/mm, while the phase range is in excess of 411°. Utilizing the proposed element, a 10 × 10 reflectarray antenna is simulated. Simulation results show that the antenna gain is 18.9 dBi at its working frequency 5.8 GHz, and has an impedance bandwidth (|S11| < -10 dB) of 3% (5.73 ~ 5.9 GHz).
关键词： Minkowski fractal loop,reflectarray element,antenna gain,square loop,phase range
更新于2025-09-04 15:30:14
-
[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Reconfigurable Reflectarrays and Transmitarrays: From Antenna Designs to System Applications
摘要： This paper reviews the recent research progress on reconfigurable reflectarrays (RRA) and reconfigurable transmitarrays (RTA) at Tsinghua University. Numerous antenna designs are presented, including W-band RRA, 2-bit RRA, 10240-element RRA, 2-layer RTA, and current-reversal RTA. Furthermore, the RRA and RTA demonstrate a promising potential in advanced wireless systems. As an example, a RRA-based security imaging system is illustrated in details.
关键词： reconfigurable,antenna,reflectarray,transmitarray
更新于2025-09-04 15:30:14
-
A Reflectarray for Generating Wideband Circularly Polarized Orbital Angular Momentum Vortex Wave
摘要： A reflectarray for generating wideband circularly polarized (CP) orbital angular momentum (OAM) vortex wave in X band is proposed. First, a dual-linearly-polarized element consisting of two rhombus-shaped metal patches etched on two dielectric substrates is designed. The element has high isolations between two polarizations and preferable linear phase responses in wide frequency band. Then, the phase distribution of the reflectarray carrying the OAM vortex wave with mode l=1 is designed, and dimensions of the elements are determined by their reflective phases. The far-field radiation patterns and near-field phase distributions are simulated to verify the proposed design. Finally, prototype of a 313-element reflectarray with a linearly polarized (LP) Vivaldi feed, which converts an incident LP wave into a reflective CP wave, is fabricated and measured. The results of measurement indicate that the reflectarray can generate CP OAM vortex wave with mode l=1 in 9-11 GHz band (a fractional bandwidth of 20%). The reflectarray also achieves 20% 1-dB gain bandwidth, and its peak gain is 19.9 dB at 11 GHz. Except for a very narrow band (10.9-11.1 GHz), its measured 3-dB axial ratio (AR) bandwidth is about 40%.
关键词： reflectarray,Wideband,orbital angular momentum,circular polarization
更新于2025-09-04 15:30:14
-
Tunable Liquid Crystal Based Phase Shifter with a Slot Unit Cell for Reconfigurable Reflectarrays in F-Band
摘要： An electrically tuned phase shifter based on the single slot unit cell and liquid crystal for a reconfigurable reflectarray antenna was presented. The simulation and measured results obtained at the F-band were used to demonstrate that the dielectric properties of a nematic state liquid crystal could be exploited to realize a slot unit cell phase shifter for the reconfigurable reflectarrays antennas. By reducing the inhomogeneous of the external electric field in the liquid crystal layer, a lower control voltage and improved model accuracy was obtained. In the experiments test, the achieved saturation bias voltage (10 V) was smaller than the previously reported structure, and the phase shift of the reflectarray greater than 300? was achieved in the frequency range 121.5–126 GHz. The maximum phase shift of 306? occurred at 124.5 GHz.
关键词： phase shifter,phase control,liquid crystal device,reconfigurable reflectarray
更新于2025-09-04 15:30:14