A millimeter-wave broadband metasurface-based antenna with a low profile is proposed. In order to guide the mode excitation, the characteristic mode analysis (CMA) is used for the design and optimization of the proposed antenna. Four sets of coplanar patches with different dimensions on a thin printed circuit board are used to generate four adjacent broadside modes, which are directly fed by a coaxial probe. Then, to expand low-frequency bandwidth, a new resonant mode is introduced by etching slots on the parasite patch. Meanwhile, the extra mode introduced does not significantly change the radiation performance of the original modes. Moreover, dual slots are etched on the mid patch fed by the coaxial probe, which moves the orthogonal modes of the chosen modes out of the operating band to reduce cross-polarization levels. The proposed antenna realized 25.02 % (30–38.58 GHz) impedance bandwidth with dimensions of $1.423\times 1.423\times 0.029{\lambda }_{0 }^3$ (${\lambda }_0$ is the wavelength at 34 GHz in free space), and the realized gain in the band is 8.35–11.3 dB.

This paper demonstrates an integrated wide-angle scanning planar phased array based on pattern reconfigurable antennas. The pattern reconfigurable antenna unit consists of four rotationally symmetrical elements with a dimension less than 0.41λ×0.41λ. By exciting different elements, the beam of the unit switches between four modes and has a 3dB coverage of ±77°, which helps the antenna array achieve an expanded scanning range. The reconfigurable principle and bandwidth enhancement method of the compact antenna unit are analyzed; the radiation efficiency and the performances of the array are also discussed. The whole system of the phased array is integrated on a multilayer hybrid PCB board, which includes a 4×4 reconfigurable antenna array, TR modules, 4-channel RF chips, a beam control circuit, and a power management circuit. The measured return loss of the antenna unit is less than -10dB in the frequency range of 27GHz to 30GHz, and the scanning range is from -68° to 68° with a maximum gain of 16.4dBi. The gain fluctuation of the array in beam scanning is less than 2dB, and the scanning range of -3dB covers ±80°.

This letter presents an enhanced-bandwidth design of compact high-order-mode (HOM) cavity-backed slot antenna array for V-band communication systems. Pairs of small-distance parallel slots are utilized as radiating elements, which have merits of enhancing bandwidth by generating electric field perturbations in the cavity. Furthermore, four shorting pins are loaded around the coupling slot to enhance bandwidths as well as to improve the gain of the antenna. Based on studies on the electric field and important parameters, the operation principles of the bandwidth enhancement are analyzed. For the proof of concept, a HOM cavity-backed slot antenna array prototype with four subarrays is fabricated and measured. The measured impedance and 3-dB gain bandwidths are 12.04% (58.16-65.61 GHz) and 13.03% (58.35-66.48 GHz), respectively, with a measured maximum gain of 18.69 dBi and maximum aperture efficiency of 58.1%. The measured results are consistent with simulated results.

In this letter, an enhanced-bandwidth multibeam antenna based on center-fed linear slot array is proposed. First, by placing the coupling slot in the center and inserting matching vias, the proposed center-fed method can enhance the bandwidth by exciting slots of linear slot array in phase in an enhanced bandwidth. To illustrate the operation principle, the electric fields of center-fed structure and the function equations among the phase, distance, and frequency are analyzed and presented. Then the multibeam application of the center-fed linear slot array with 4 × 4 Butler matrix beamforming network is fabricated and measured. The measured impedance and 3-dB gain bandwidths are 13.69% and 14.09%. When exciting different ports, the beam angles fluctuate around -38°, -20°, 20°, and 40°, with peak gains of 16.66, 17.65, 17.74, and 16.88 dBi

This letter introduces a broadband magneto-electric dipole antenna with a stable broadside radiation pattern. The proposed antenna incorporates rectangular parasitic elements and grooves on the arc-shaped radiating patch, which introduce a current cancellation mechanism. This mechanism ensures that the main radiation pattern remains highly consistent across the operating band, thereby guaranteeing radiation pattern stability over the entire frequency range. Furthermore, in combination with the metal bracket, the design enables orthogonal superposition of the electric and magnetic current distributions, contributing to broadside radiation pattern. The antenna features a compact aperture size of 0.4λ₀ × 0.4λ₀ × 0.1λ₀. Within the operating band, the radiation efficiency exceeds 85%. Both simulated and measured results demonstrate an impedance bandwidth (IBW) of 77% (0.4–0.9 GHz), a peak gain of 5.07 dBi with a variation of only 0.37dBi, and an E-plane half-power beamwidth (HPBW) ranging from 92° to 123°.

A wideband pattern-reconfigurable antenna (PRA) integrating an asymmetric coplanar strip (ACS), coupled patches, and defected ground structure (DGS) loading is presented. The ACS provides the basic tilted-beam radiation, while the coupled patches and DGS provide complementary impedance-matching contributions in the upper and lower portions of the operating band, respectively. Their interaction with the original ACS response establishes three resonant responses that collectively broaden the matched band. The loading structures and two-PIN switching scheme are jointly designed to realize broadband radiation pattern reconfiguration, maintaining two selectable tilted-beam states across the wide operating band through a single feeding port. A prototype is fabricated and achieves a measured common −10 dB impedance bandwidth of 57.6%, covering 4.2–7.6 GHz. A radiation efficiency above 90% is obtained at the tested frequencies, and the measured radiation patterns generally maintain their overall tilted-beam shapes, with sidelobe levels more than 9 dB below the main beam. The proposed design provides a practical solution for broadband directional wireless applications requiring flexible coverage.