This paper presents a bandwidth-enhanced, low-profile dual-polarization (dual-pol) patch antenna array with a height of only 0.03λ₀ for glass-enclosed mobile platforms in 5G-enabled IoT applications at the millimeter-wave band. The bandwidth improvement and low-profile characteristic are achieved through a single-layer radiating patch fed by closely positioned lateral microstrip resonators, forming a multi-resonance structure that expands bandwidth while reducing the overall height by minimizing vertical feeding components. Dual-pol performance is accomplished via common-mode excitation of back-to-back C-shaped quarter-wavelength resonators on one side of the patch for one polarization, and differential-mode excitation of folded line-shaped resonators symmetrically placed on opposite sides for the orthogonal polarization, achieving extended bandwidth and high isolation. Building on this antenna element, a 1×4 dual-pol phased array is implemented for beam steering, fabricated using high-density interconnect (HDI) technology. Measurements reveal an operating bandwidth of 25.56–28.04 GHz (a fractional bandwidth of 9.5%) forx-pol and 24.42–28.49 GHz (15.6%) for y-pol. Beam scanning across ±45° shows a gain degradation of less than 3 dB, with cross-polarization levels remaining below -20 dB within the main lobe at each scan angle. This design is intended for integration within the camera region of a mobile terminal and has been optimized for operation in an under-glass environment. Performance tests conducted with a glass cover confirm the robustness of the design as an effective under-glass antenna for terminal applications.

This study introduces an innovative K-/Ka-band planar active shared-aperture phased array (ASAPA), advancing low earth orbit (LEO) terminal design through synergistic innovations in shared-aperture topology and three-dimensional (3D) integration. Breaking from conventional shared-aperture topologies plagued by cross-band interference and radiation pattern distortion, we propose a partial-element-reuse-based (PER) topology that strategically repurposes 50% of dual-band dual-polarized elements for simultaneous transmit and receive (STAR) operation. This configuration eliminates active element pattern distortion while achieving a reduction in element count, enabling wide-angle beam scanning essential for dynamic satellite tracking. Furthermore, a sandwich-structured printed circuit board (PCB) lamination method is further employed to streamline integration by partitioning functional modules into antenna, coupler, and active circuit layers interconnected via ball grid array (BGA) technology. This 3D integration strategy simplifies vertical interconnects, minimizes PCB layer requirements, and enhances thermal dissipation through embedded air gaps. Experimental results validate robust beamforming performance across ±60° scanning ranges for both transmitting and receiving arrays, achieving high transceiver isolation and signal integrity, which are imperative for high-capacity satellite links. By addressing key bottlenecks in LEO terminal design, the proposed innovations can accelerate the deployment of energy-efficient, cost-effective satellite networks, thus advancing the 6G vision of ubiquitous global connectivity.

A wideband dual-polarized planar phased array with filtering characteristic is presented. The array element, working as a filtenna, is implemented with a dual-polarized stacked patch coupled by a cross-shaped slot. The parasitic patch not only generates an extra resonant mode to broaden the bandwidth but also introduces a radiation null at the upper edge of passband. Another radiation null at the lower edge of passband is introduced by loading the parasitic strips around the driven patch. The filtering mechanism is further verified by constructing an efficient equivalent circuit model. Two sets of carefully designed feedlines are arranged orthogonally in a limited size (meet the space requirement of a phased array) and combined with the cross-shaped slot to improve the out-of-band suppression level in both upper and lower stopbands. The proposed element is subsequently deployed in building a low-profile dual-polarized phased array. A prototype is finally implemented, and the measured results agree well with the simulated ones. A ±60° scanning range accompanied with a gain fluctuation within 5.2 dB is observed in the operating passband ranging from 12.3 to 15.8 GHz. The average out-of-band suppression level among different beam directions is found better than 12 dB.

A low-cost millimeter-wave wideband filtenna integrating filtering and radiation performance for next-generation millimeter-wave (mmWave) Internet of Things (IoT) devices is proposed in this article. The filtering performance is achieved by utilizing the intrinsic high-pass property of a microstrip-fed magneto-electric dipole (ME-dipole) and filtering feeding mechanism. Several shorted parasitic patches are settled around the E-dipole to enhance the radiation performance within the operating band and develop suppression levels at both the lower and upper bands. A stepped cross-shaped microstrip-line structure is added in the center of the radiating aperture to generate two resonances, so that the in-band impedance performance and the selectivity can be improved. Measurement results indicate that the proposed filtenna achieves a wide operating bandwidth of 30.26% (22.8-31.4 GHz), a peak gain of 8.21 dBi and an out-of-band gain suppression better than 23 dB. Furthermore, a 2×2 filtenna subarray is constructed with some shorted parasitic patches being shared, and then, a 4×4 circularly-polarized (CP) sequential rotated (SR) array is also delicately designed using the 2×2 filtenna subarray. Remarkable operating bandwidths and appropriate out-of-band suppression performance with simplistic structures are all confirmed well through experiments. The outstanding performance of the proposed filtenna and its arrays makes them potential candidates for the B5G/6G mmWave communications.

In the era of 5G and beyond, the strategic utilization of both sub-6 GHz and millimeter-wave (mmWave) spectrums supports diverse communication services. Through smartphones, consumers can conveniently access a wide range of 5G/6G-enabled Internet of Things (IoT) scenarios anytime and anywhere. In this paper, mmWave and sub-6 GHz aperture-shared antenna and array are proposed for mobile terminals. For the mmWave antenna design, a slot radiating array is integrated into the metallic frame of a smartphone. This design incorporates a differential square-ring feeder and utilizes hybrid mode operation, enabling dual-polarized radiation capability across a wide operating frequency band. Importantly, this configuration requires only two metal layers with a 1.0-mm profile. Sharing the same frame, an inverted-F antenna (IFA) and a hybrid mode antenna with loop antenna and IFA operation are designed to work in sub-6 GHz bands. With the design principle of equal clearance, the sub-6 GHz antennas can perform well with the coexistence of the mmWave array. This approach is particularly applicable for sub-6 GHz antennas of different modes and frequencies. The proposed 1×4 mmWave phased array prototype demonstrates a -10 dB bandwidth of 23.3-30.8 GHz (covering the 5G n257/258 bands), a beam scanning range of ±40∘, and an in-band realized gain above 10.3 dBi. The sub-6 GHz antennas effectively cover 5G bands n1/2/3/7/18/28. By utilizing impedance tuning technique, the lower band can be further tuned to cover the bands n8/5.

This article presents a$K$-band high gain monopulse variable inclination continuous transverse stub (VICTS) antenna for satellite-aided vehicular communications. The radiating part is divided into four regions and fed by an air-filled single-layer E-plane waveguide comparator cascaded with two groups of mirror-symmetric multiple-port excited linear source generators (LSGs). Two waveguide delay lines are carefully designed to compensate the phase difference between the adjacent radiating regions in the desired frequency band. Combined with the nonuniform slow-wave structure underneath the radiating slots, excitation signal with uniform phase distribution can be obtained, and then, the sum and difference patterns can be produced by using the comparator. For verification, a prototype operating at$K$-band is designed and demonstrated. The experimental results show that the reflection coefficients for the sum and difference patterns are all lower than −10 dB within the frequency range of 19–21 GHz. The gain drop of the sum pattern is less than 5.7 dB within the beam scanning range of −1° to −62° at 21 GHz, while the amplitude imbalance and null depth of difference patterns are less than 4.5 and −20.6 dB, respectively. The proposed antenna can be a potential candidate for the future Internet of Vehicles.