In this paper, an anisotropic coding metasurface is proposed to achieve dual-mode vortex beam generator by independently manipulating the orthogonally linearly polarized waves. The metasurface is composed of ultrathin single-layer ground-backed Jerusalem cross structure, which can provide complete and independent control of the orthogonally linearly polarized incident waves with greatly simplified design process. As proof of concept, a metasurface is designed to generate vortex beams with different topological charges under orthogonal polarizations operating at 15 GHz. Experimental measurements performed on fabricated prototype reveal high quality, and show good agreements with theoretical designs and simulation results. Such ultrathin dual-mode vortex beam generator may find potential applications in wireless communication systems in microwave region.

In this paper, a high-order mode (TE340-mode) empty substrate integrated cavity (ESIC) fed high-gain circularly polarized 2×2 patch antenna array is presented. By using ESIC TE340-mode cavity, compact size and low-loss feeding network is achieved. Each cavity-backed circular patch is etched by a pair of inclined slits to achieve circular polarization. To verify the concept, a 2×2 antenna array is fabricated and measured. The measured -10 dB impedance bandwidth of the array is 19.58% (from 36.85 to 44.85 GHz). The measured 3-dB axial ratio bandwidth is 5.74% (from 42 to 44.5 GHz). The measured total gain is 14.02 dBi. The proposed high-gain and low-cost circularly polarized antenna array can be a proposing candidate in the future millimeter-wave communications.

This paper proposes a monostatic backscatter communication system with enhanced isolation between excitation and receiver. This enables a mechanism akin to simultaneous co-frequency full-duplex operation, allowing the receiver to effectively amplify and quantify the weak reflected backscatter signals, subsequently demodulating them to extract valid data. Compared to RFID systems, which also employ monostatic backscatter communication, this approach can substantially extend the effective communication range. Furthermore, the exciting source and receiver are integrated in the same system, which makes the base-station system's framework compatible with a common WiFi router. Meanwhile, the communication power consumption of the remote node is significantly decreased

In this paper, a broadband left-handed circularly polarized (LHCP) corrugated horn antenna using a dielectric circular polarizer is proposed. Circularly polarized (CP) waves are generated by inserting an improved dovetail-shaped dielectric plate into the circular waveguide. Compared with the traditional dovetail-shaped circular polarizer, the proposed improved dovetail-shaped circular polarizer has a wider impedance bandwidth and 3 dB axial ratio bandwidth. A substrate-integrated waveguide (SIW) structure is designed as a wall to eliminate the influence of fixed grooves on the circular polarizer. The simulated reflection coefficient of the dielectric plate circular polarizer is less than −20 dB in the frequency band from 17.57 to 33.25 GHz. Then, a conical corrugated horn antenna with five corrugations and a four-level metal stepped rectangular-circular waveguide converter are designed and optimized. The simulated −10 dB impedance and 3 dB axial ratio (AR) bandwidths of the circularly polarized horn antenna integrated with the polarizer are 61% (17.1–32.8 GHz) and 60.9% (17.76–33.32 GHz), respectively. The simulated peak gain is 17.34 dBic. The measured −10 dB impedance is 52.7% (17.2–27.5 GHz).

A two‐layered wideband single‐fed circularly polarised (CP) antenna is presented by the authors. A single‐fed corner‐truncated square patch with four identical rectangular matching branches acts as a bottom‐driven patch to generate CP radiation. To broaden the 3‐dB axial ratio (AR) bandwidth, a similar patch with a larger size is loaded atop the driven patch as a parasitic patch. The measured results show that the proposed CP antenna has a 17.9% impedance bandwidth from 2.13 to 2.55 GHz and an 11% 3‐dB AR bandwidth from 2.15 to 2.4 GHz, respectively. The measured total gain is 7.1 dBic. The results indicate that the proposed antenna is a good candidate for Wireless Local Area Network band applications.

In this paper, a low-temperature co-fired ceramic (LTCC)-based E-shaped planar in-verted-F antenna (PIFA) is proposed for circularly polarized (CP) at D-band (110-170GHz). For stable CP radiation characteristic, a densified self-sequential rotation feeding (DSRF) technique is applied for 2×2 subarray. Certain perturbance of field distribution is achieved by arranging the coupling feed disks properly. Hence, a TE410-mode/quasi-TE330 high-order-mode (HOM) substrate integrated waveguide (SIW) cavity is excited with four coupling feeding slots properly arranged to obtain equal amplitudes and sequential 90°-phase shifts, which can be deemed as high-order-mode based densified self-sequential rotation feeding (HOM-DSRF) configuration. Thanks to the proposed HOM-DSRF configuration, the overall dimension of the 2×2 CP subarray is only 1.05λ×1.05λ with a simulated aperture efficiency up to 96%, which is significantly superior to conventional sequentially rotation feeding methods in terms of overall dimension and aperture efficiency. Finally, a 4×4 antenna array is designed, fabricated and measured. The measured impedance bandwidth and 3-dB axial ratio bandwidth are 10.4% from 145.7 to 161.7 GHz and 10.5% from 144 to 160 GHz, respectively. The measured peak gain is 15.1 dBic, with measured aperture efficiency up to 71%. The measured results agree well with the simulated ones. The proposed HOM-DSRF configuration has potential applications for terahertz (THz) CP antenna array designs.