A Dual-Polarized Linear Antenna Array With Improved Isolation Using a Slotline-Based 180° Hybrid for Full-Duplex Applications

In this article, a dual-polarized planar phased array with high polarization isolation and low cross-polarization is presented operating from 4 to 18 GHz, i.e., 4.5:1. The proposed array is comprised of tightly coupled dipoles with integrated coupled-Marchand baluns. To improve the uniformity of fields distributed on the array, the center-feeding dipole is used in this design instead of the conventional edge-feeding one at first. Then, the outer conductors of the feed are composed of a group of shorted vias with the proper number and position. Based on these methods, the output balance of the balun is significantly improved, resulting in high isolation between ports with different polarization modes. Furthermore, this feed has a natural ability to suppress the D-plane common mode resonance. The capacitive metallic annular plate over adjacent radiating elements and the thick aluminum plate with an air cavity placed under the array are employed together to suppress the in-band coupled-loop modes. The infinite array simulation indicates that the array can achieve transmit (Tx)/receive (Rx) isolation more than 48 dB at broadside. Isolation better than 32 and 30 dB can be achieved when scanning to 45° in E-/H-planes and 60° in E-plane, respectively. The cross-polarization level is below −54 dB at broadside and remains below −29 dB when scanning to 60° in E-plane as well as 45° in H-plane. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12\times12$ </tex-math></inline-formula> dual-polarized antenna array is fabricated and measured to validate the correctness of this design. This type of antenna can be applied in wideband simultaneous transmit and receive (STAR) monostatic systems.

A compact wideband dual-polarized omnidirectional antenna array for base-station applications is proposed. It consists of ten antenna units. To generate ±45° dual-polarized ominidirectional radiation with low gain variation for each unit, three close-in crossed-dipole elements are uniformly arranged in a regular triangle shape and excited by two 1-to-3 power dividers with equal magnitude and phase, acting as a dual-polarized loop antenna. To obtain wide impedance bandwidth for each unit, the dipole element and power divider are designed to operate in a wide and well-matched band. Moreover, the unit features steady structure, easy fabrication, and high scalability, which makes it convenient to form an antenna array. To achieve a high gain for base-station applications, a ten-unit antenna array is designed, fabricated, and measured. A wide impedance bandwidth of 52.3% (1.62–2.77 GHz) for standing-wave ratio (SWR) < 1.5 and a high port-to-port isolation of 26 dB are realized. It also features a high gain of 10.3 ± 0.9 dBi and a small gain variation of less than 2.5 dB in the horizontal plane. Additionally, the sidelobe suppression of 18 dB and null filling below the main vertical beam are obtained by the designed feeding networks. These results make the proposed design attractive in base-station applications.

To meet the requirements of a millimeter-wave (mmWave) communication system prototype complying with 5G (24.25-29.5GHz) and B5G/6G (30-33GHz) standards, this letter presents a compact wideband widebeam ±45° dual-polarized dipole element antenna to form a wideband phased array antenna (PAA) covering the entire 24-33GHz (∼31.6%) band. First, by placing two orthogonal coupling feeding baluns over a dual-polarized dipole to excite the dipole's two pairs of orthogonal arms and employing four parasitic patches, a ±45° dual-polarized dipole element antenna is developed, showing a compact size (0.34λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.34λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> @24GHz), wide -14-dB impedance bandwidth (24-33GHz, 31.6%), wide 3-dB beamwidth (>100°), high polarization isolation (>25dB), and high cross-polarization discrimination (XPD) (>25dB) within the -14-dB impedance bandwidth. Then, based on the element antenna, a 4×4-element ±45° dual-polarized PAA is designed, fabricated using the LTCC process, and measured. The measurements show that, within the entire 24-33GHz band, the broadside scanning gain of the PAA is up to 14dBi, and the 3-dB gain variation scanning range is >±41° with a peak up to ±60º.

In this study, we present a dual-band (28/39GHz) 2 by 2 antenna array design on a 10(4+2+4) multi-layer organic substrate with broad bandwidth and higher isolation onto a compact AiP module. In addition, the H-type slot antenna structure can improve interference and isolation between 28 and 39GHz bands. The measured result shows the isolation can larger than 15dB between low and high band. For antenna measurement, the spherical of probing chamber is utilized to validate 28/39GHz antenna pattern and performance with a package level passive testing. Our AiP measured result shows the return loss is better than 10 dB in 23.5-30.5 GHz range, with ~7 GHz bandwidth and provides a high-gain per element (above ~6 dBi) radiation pattern for 28GHz applications. For 39GHz band, the antenna has 7 GHz bandwidth and provides a 5 dBi gain between 38-45 GHz. Comparison of S-parameter between simulated and measured results, there is a good correlation to obtain the quality of manufacturing. Furthermore, a 28GHz beamforming array is designed and demonstrated. The beamfoming array consists of a four-channel transceiver with 2 x 2 antenna array. The beamformer IC is implemented by TSMC 90-nm CMOS technology and the flip-chip bonded on BT substrate. For beamforming test, an integrated socket and load board are designed for support the mmWave module and then connection between DUT and test system. The load board substrate includes the IF, LO, and DC distribution network for respectively. There are 4-channel transmit beamforming array front-end module for testing. Finally, the 3D beam steering of 2 by 2 antenna array is measured with multi-states at 28 GHz, with a maximum realized gain of 11.8 dBi achieved in the main beam (θ=0°). It shows that beamforming can be generated at a specific beam direction by controlling the phase of the signal in each antenna element.

In this paper, a novel design of dual-polarized microstrip antenna array for Ka band is presented. A single layer mirostrip antenna is excited by coplanar coupled method, which can increase the isolation between the two ports. From the measurement results, a steep isolation better than -33dB and cross polarization level less than -30dB are achieved with the presented design. Furthermore, the proposed antenna structure takes good features of simplicity and high integration.

ABSTRACTThis article presents the design and performance analysis of a high gain dual-polarized two-element cylindrical dielectric resonator antenna (DRA) array excited by two orthogonally placed H-shaped apertures. The antenna is operated in dual linear polarized mode by exciting TM110 (HEM11) mode in two DRAs using aperture coupling. The proposed antenna has a −10 dB impedance bandwidth of 9.52% (6.0–6.6 GHz) with isolation more than 40 dB among the two ports. Realization of gain enhancement and high isolation are accomplished by simultaneously exciting two DR elements using a pair of wideband Wilkinson's power divider placed on the bottom side of the substrate. The measured gain of the proposed antenna for both the ports is found to be 12.5 dB with a front to back ratio of 16 dB. The antenna has an overall radiation efficiency of 94% and symmetrical radiation patterns with co-polarization levels 40 dB higher than the cross-polarization in both the principal planes (XY and XZ) of bore-sight direction.

A single-layer dual-polarized patch antenna loaded by T-shape microstrip stubs to achieve high port isolation is developed in this paper. This patch is side-fed in single-end form to simplify the connection to most RF chips. In addition, this patch only occupies single substrate layer with the ultra-low profile of 0.40λ0 × 0.40λ0 × 0.02λ0. High port isolation is realized by the loading effect of stubs. Simulated results show that this proposed antenna can cover 24GHz to 24.25GHz ISM band with peak realized gain of 5.2dBi and symmetrical broadside radiation pattern. Meanwhile the worst isolation between two orthogonally polarized ports is above 32dB considering PCB manufacturing tolerances.

In this letter, a dual-polarized array antenna with wide bandwidth and high gain is presented for Wi-Fi/WiMAX application. The array antenna comprises a single substrate layer, a radiation patch layer, and conical elements. For comparison, an array antenna with two layers of substrates is designed. The reflection coefficient of the antenna with cones is better than -10 dB in the range of 4.9 ~ 5.96 GHz with a relative bandwidth of 19.52%, which is higher than that of the antenna with two substrate layers (14.05%). The maximum gains of the proposed antenna with cones achieve approximately 19.2 and 18.8 dBi at 5.5 GHz for the two orthogonal polarizations, respectively. In addition, high isolation and low cross-polarization levels are observed.

A broadband dual-polarized planar antenna is proposed for 2G/3G/LTE base stations. The dual-polarized antenna is composed of two perpendicularly crossed bow-tie dipoles. Each bow-tie dipole is excited by a microstrip stub that is directly fed by a coaxial line, making the dual-polarized antenna full planar. Due to the coupling between two crossed bow-tie dipoles, a broad bandwidth is achieved. It is shown that the dual-polarized antenna has a bandwidth of 45% (1.7-2.7 GHz) for return loss >15 dB with an isolation of higher than 30 dB between two polarization input ports. The dual-polarized antenna has a half-power beam width (HPBW) of around 65 ° and an average gain of 8.5 dBi for slant ±45° polarizations. An 8-element dual-polarized planar antenna array is developed for base station applications. A bandwidth of 56% (1.63-2.9 GHz) is obtained for the antenna array. The antenna gain of the array is about 16 dBi and the HPBW is 65±8° for each polarization.

A novel millimeter-wave spoof surface plasmon polaritons (SSPPs)-fed dual-polarized microstrip patch antenna array is proposed in this article. A dual-polarized single-layered square patch antenna fed by SSPPs is investigated first acting as the radiators. A method of directly connecting two orthogonal SSPPs with two edges of the square patch is introduced to excite the TM10 and TM01 modes and to achieve promising performance simultaneously. The fabricated antenna element has a measured overlapped impedance bandwidth of 13.7%, an isolation of more than 15 dB between the two inputs, a gain of up to about 6 dBi, and stable dual-polarized radiation patterns. With the use of two SSPPs branches printed on different sides of the substrate, a compact SSPPs power divider with adjustable power dividing ratio is then investigated for realizing the series SSPPs feed network, whose design considerations are discussed in detail. By combining the feed network with the patch elements, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times $ </tex-math></inline-formula> 4 SSPPs-fed dual-polarized microstrip patch antenna array is fulfilled. The fabricated prototype confirms a bandwidth of 15% and dual-polarized broadside radiations. Benefitted from the simple single-layered geometry without the metallic ground plane over the major region of array geometry and the dual-polarized unidirectional radiation, the presented designs are valuable to emerging millimeter-wave applications.

This work presents a novel dual-polarized antenna array tailored for Internet of Things (IoT) applications, specifically designed to operate in the millimeter-wave (mm-wave) spectrum within the frequency range of 30–60 GHz. Leveraging printed ridge gap waveguide (PRGW) technology, the antenna ensures robust performance by eliminating parasitic radiation from the feed network, thus significantly enhancing the reliability and efficiency required by IoT communication systems, particularly for smart cities, autonomous vehicles, and high-speed sensor networks. The proposed antenna achieves superior radiation characteristics through a cross-shaped magneto-electric (ME) dipole backed by an artificial magnetic conductor (AMC) cavity and electromagnetic bandgap (EBG) structures. These features suppress surface waves, reduce edge diffraction, and minimize back-lobe emissions, enabling stable, high-quality IoT connectivity. The antenna demonstrates a wide impedance bandwidth of 24% centered at 30 GHz and exceptional isolation exceeding 40 dB, ensuring interference-free dual-polarized operation crucial for densely populated IoT environments. Fabrication and testing validate the design, consistently achieving a gain of approximately 13.88 dBi across the operational bandwidth. The antenna’s performance effectively addresses the critical requirements of emerging IoT systems, including ultra-high data throughput, reduced latency, and robust wireless connectivity, essential for real-time applications such as healthcare monitoring, vehicular communication, and smart infrastructure.

A wideband differential-fed patch antenna with high isolation and high selectivity is presented. The differential-fed method is used to provide the antenna with high polarization isolation characteristic. A parasitic patch is adopted in the design not only to improve the impedance bandwidth, but also to generate a radiation null at the upper band-edge. Filtering response is improved by etching slots and loading resonant stubs on the feeding lines. Simulated results show that the proposed DFDP filtering antenna has an operation band of 34.16% (from 3.86 to 5.45 GHz) for |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dd11</sub> | <; -10 dB and a maximum gain of 9.64 dBi, and the cross-polarizaiton level is below -27 dB. Moreover, a high out-of-band gain-suppression level which reaches 21.9 dB is also obtained.

An ultra-wideband (UWB) dual-polarized microstrip slot antenna with high port isolation and planar structure is presented in this letter. This antenna consists of a monopole and a tapered microstrip feed line, they are used for obtaining UWB characteristic and generating two orthogonal polarization modes. Furthermore, the good impedance matching can be attained through etching slots on the ground plane. The simulated results point out that the antenna can cover the input impedance bandwidth of 3.1∼10.6 GHz with reflection coefficient <−10 dB, and the port isolation is better than 22 dB over the whole operating band. It also has a good radiation performance and is appropriate for UWB applications.

This work presents a wideband hybrid-fed ±45o linear dual-polarized patch antenna design for sub- 6 GHz 5G base stations. Two polarizations are created by a slot-coupling with rectangular H-slot (+45) and a capacitive coupling with modified L-probe (−45). Antenna exhibits wideband −10 dB impedance bandwidths of 40.7% and 35.6% for slot-fed and probe-fed ports, respectively. Due to the special design of suspended stacked patches with hybrid-fed excitations, high port isolation ( 38 dB) are achieved. Symmetric and directional radiation patterns with stable gain are obtained in E and H planes for each polarization. Compared to its bandwidth, antenna is low-profile (10.6 mm) with front-to-back ratio greater than 22 dB. Simulations and experimental results are reported and discussed.

Theoretical analysis and simulation verification of the method of widening the bandwidth and improving the cross-polarization isolation of the dual-polarization microstrip antenna array are presented in this paper. Multiple-resonators technique has been used to extend the bandwidth. Anti-phase and sequential rotation feeding techniques are adopted to improve the cross-polarization isolation. Two kinds of linear array with different number of elements are demonstrated respectively. Simulated results show that the characteristics of broadband and high cross-polarization isolation are achieved by employing the abvoe techniques.