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This article presents a new design of a differentially fed substrate integrated planar antenna array with dual-polarization. Compared with the traditional dual-polarized antenna arrays, the proposed array antenna has the advantages of simple configuration, high cross-polarization discrimination (XPD), and high gain. The 2 × 2-element subarray design with a via-loaded crossover structure is used, which reduces the complexity of the array antenna. The operation bandwidth is improved by generating three resonances in the subarray. An 8 × 8 antenna array is designed, prototyped, and tested to exemplify its potential applications in large dual-polarized antenna arrays. A planar orthomode transducer is used to achieve differential excitation for the antenna array. The measured results show that the proposed antenna array has an impedance bandwidth of 19.2–20.7 GHz for |S11|< −10 dB and port isolation higher than 20 dB. The array antenna exhibits a high XPD of 43 dB and a flat gain of about 22.2 dBi within the bandwidth. [ABSTRACT FROM AUTHOR]

A hybrid metasurface (HMS) is proposed to form a low-profile wideband antenna array. The antenna element is an array of $4\,\,\times4$ square metal patches and fed by a $50~\Omega $ microstrip line through an H-shaped coupling slot on the ground plane. Only are the edge patches of HMS antenna element grounded by shorting pins for the suppression of surface waves and cross-polarization levels as well as the enhancement of the gain. With the HMS antenna element, a compact $2\times 2$ array with an overall size of $1.58\lambda _{0} \times 1.58\lambda _{0} \times 0.068\lambda _{0}$ ($\lambda _{0}$ is the free-space wavelength at 5.0 GHz) is designed, where the adjacent elements share the edge patches of the elements. The measurement shows the impedance bandwidth of 28% (4.41–5.85 GHz) for $\vert \text{S}_{11}\vert \le -10$ dB is obtained, and the boresight gain is greater than 8.4 dBi across the operating band, covering both fifth-generation (5G) sub 6 GHz and WiFi bands. [ABSTRACT FROM AUTHOR]

A two-port pattern reconfigurable three-layered Yagi-Uda patch antenna with ±45° dual-polarization characteristic is presented. A driven patch (DP) and two large parasitic patches (LPPs) are printed on the top side of the middle layer, and the middle and bottom layers share a common metal ground. Two microstrip feedlines printed orthogonally on the bottom side of the bottom layer are used to feed the DP through two H-shaped slots etched in the ground. The LPPs are connected to/disconnected from the ground controlled by switches. By adjusting the connection states of the LPPs, one wide-beam mode and three narrow-beam modes can be obtained in both polarizations. A small parasitic patch is printed on the top side of the top layer to improve the pattern coherence of the two polarizations. This antenna is studied by both simulation and measurement. The measured common bandwidth of the four modes in both polarizations is 3.32–3.51 GHz, and the isolations between two polarizations in all the modes are higher than 20 dB. The low-profile antenna is very suitable for microbase-station applications. [ABSTRACT FROM PUBLISHER]

A novel method of achieving a single-feed circularly polarized (CP) microstrip antenna with both broad impedance bandwidth and axial ratio (AR) bandwidth is presented. The CP characteristics are generated by employing a resonator to excite the two orthogonal modes of the patch via two coupling paths and the required 90° phase difference is achieved by using the different orders of the two paths. The presented method, instead of conventional methods that power dividers and phase delay lines are usually required, not only significantly enhances the bandwidths of the antenna but also results in a compact feed, reduced loss and high gain. Based on this method, a dual-band shared-aperture CP array antenna is implemented for $C$ -/ $X$ -band satellite communications. The antenna aperture includes a $2 \times 2$ array at $C$ -band and a $4 \times 4$ array at $X$ -band. To accommodate the $C$ - $X$ -band elements into the same aperture while achieving a good isolation between them, the $C$ -band circular patches are etched at the four corners. The measured results agree well with the simulations, showing a wide impedance bandwidth of 21% and 21.2% at $C$ -band and $X$ -band, respectively. The $C$ -band and $X$ -band 3 dB AR bandwidths are 13.2% and 12.8%. The array also exhibits a high aperture efficiency of over 55%, low sidelobe ( $C$ -band: −12.5 dB and $X$ -band: −15 dB), and high gain ( $C$ -band: 14.5 dBic and $X$ -band: 17.5 dBic). [ABSTRACT FROM PUBLISHER]

Design of a circularly polarized reconfigurable reflectarray antenna (RRA) at X band is presented. The RRA element employs concentric dual split rings, and can be mechanically rotated to obtain continuous 360° phase coverage with negligible element loss. A prototype with 15\times15 manually rotated elements is first computed, simulated, and measured. Full-wave simulations show that the gain of the beam focused in ( \theta =20^{\circ } , \varphi = 0^{\circ } ) direction is 25.8 dB and the 1-dB gain bandwidth is over 28.6%. The measured results show that the beam at ( \theta = 20^\circ , \varphi = 0^\circ ) direction achieves the maximum gain of 25.6 dB, corresponding to an aperture efficiency of 51.8%. The beam-steering capability of the RRA is measured within ±60° angular range, and well-defined scanned beams are obtained with maximum scan loss of 3.7 dB. The versatile beam-forming capability of the RRA is also verified by synthesizing a square shaped beam and a cosecant shaped beam. Another micromotor-controlled prototype with 756 elements on an octagonal aperture is fabricated and its measured radiation performance validates the feasibility of the proposed design as well. [ABSTRACT FROM PUBLISHER]