A novel wideband substrate integrated waveguide (SIW) cavity-backed antenna element and its array are proposed in this letter. The proposed linearly polarized array element consists of a SIW cavity, stacked patches, and a coaxial probe. The SIW cavity-backed array element is implemented with physically connected stacked patch. The coaxial pin is directly connected to the two patch radiators. Blind and buried vias were avoided, this work significantly reduces the manufacture cost and complexity. The array features light weight and simple feed structure. The proposed element exhibits an impedance-matching bandwidth of 18.2% (14.5–17.4 GHz) for | S ₁₁ |<−10 dB. Simulation results illustrate that the infinite array can scan up to ±80° in the H -plane with 8% bandwidth (14.4–15.6 GHz), under the criterion of active voltage standing- wave ratio (VSWR) ≤ 3. For verification purposes, a 4 × 16 active phased array antenna prototype is fabricated using the conventional microwave multilayer printed circuit board (PCB) process. The measured results agree very well with simulations.

A new efficient synthesis method of angular selective surfaces (ASSs) based on the accurate equivalent circuit model is proposed. The angular dispersion of different components under oblique incidence is modeled by virtual lumped elements in the angular domain. The processes of obtaining the equivalent circuit for substrates, electrically small grids and patch arrays are presented in detail. The synthesized circuits are simple and accurate. Full-wave simulations are carried out to obtain the angular dispersion of different structures, and the calculated results are in good agreement with those of the equivalent circuit. A third-order ASS with bandpass response and a second-order ASS with a tunable bandwidth are given as design examples. The implemented second-order ASS shows the 0.33 to 0.52 tunable bandwidth in the angular domain. The transmission loss is better than 1.2 dB when the incidence angle is 65 $^\circ$ –77 $^\circ$ . The simulation results and calculated results are in good agreement with the measured results.

A modified electromagnetic‐bandgap (M‐EBG) structure and its application to planar monopole ultra‐wideband (UWB) antenna are presented. The proposed M‐EBG which comprises two strip patch and an edge‐located via can perform dual notched bands. By properly designing and placing strip patch near the feedline, the proposed M‐EBG not only possesses a simple structure and compact size but also exhibits good band rejection. Moreover, it is easy to tune the dual notched bands by altering the dimensions of the M‐EBG. A demonstration antenna with dual band‐notched characteristics is designed and fabricated to validate the proposed method. The results show that the proposed antenna can satisfy the requirements of VSWR < 2 over UWB 3.1–10.6 GHz, except for the rejected bands of the world interoperability for microwave access (WiMAX) and the wireless local area network (WLAN) at 3.5 GHz and 5.5 GHz, respectively.

This communication proposes a reconfigurable reflectarray (RA) with decoupled RHCP/LHCP 2D beam steering. A simple-structured unit with mechanical reconfigurability is designed to achieve the 1×1-bit dual-circularly-polarized (dual-CP) phase modulation, which enables the decoupled 2D scanning of the dual-CP beams. A prototype of the designed reconfigurable dual-CP RA is tested under two working scenarios. For the RHCP beam at (45°, -30°) and the LHCP beam in (135°, 0°~-50°), the RHCP/LHCP gain fluctuation is less than 0.9/2.9 dB. For the LHCP beam at (135°, -30°) and the RHCP beam in (45°, 0°~-50°), the RHCP/LHCP gain fluctuation is less than 3.0/0.7 dB. For the RHCP and LHCP beams at (45°, -30°) and (135°, -30°), the axial ratio (AR) bandwidth is over 24% (AR < 2 dB), and the overlapped 1-dB gain and AR < 2 dB bandwidth is 7.5%. The prototype also exhibits ideal AR beam width of over 6° (AR < 2.5 dB) and maximum aperture efficiency of 20.9%. The proposed reflectarray design simultaneously realizes independent polarization control and dual-CP 2D beam steering for the first time, which is of great value in many fields.

A novel low‐profile substrate integrated waveguide (SIW) cavity‐backed slot antenna with an enhanced gain is proposed. By etching four parallel transverse slots at the edges of the hexagonal SIW cavity as the radiating elements, higher resonance mode of quasi‐TM ₃₁₀ can be excited to achieve gain enhancement. A fabricated prototype with a size of 1.3 λ ₀ × 1.3 λ ₀ × 0.025 λ ₀ has been measured. Results show that the proposed design achieves a 10‐dB impedance matching bandwidth of 195 MHz and a maximum boresight gain of 10.74 dBi. The proposed antenna exhibits a high front‐to‐back ratio and low cross‐polarisation level. It still retains the advantages of low cost, ease of fabrication, and easy integration with planar circuits, making it a good candidate for low‐cost mass‐production.

In this paper, a single-fed circularly polarized (CP) aperture-coupled antenna with multilayer structure is proposed for satellite applications in Ku-band. It is composed of substrate integrated waveguide (SIW) cavity, aperture coupling slot, hollow cavity, and stacked patches. CP operation is realized by embedding a pair of L-shaped strips around the two opposite corners of the square radiation patch. Simulation results show an impedance bandwidth (IBW) with Sl1<;-10dB from 13.5 to 19 GHz (33.8%) and a 3-dB axial ratio bandwidth (ARBW) from 15.5 to 16.4 GHz (5.6%), and gain of 5.8 ± 0.2 dBi across the 3-dB axial ratio bandwidth. The overall volume of the antenna is 0.47λ ₀ ×.47λ ₀ ×0.12λ ₀ at 15.8 GHz.