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Base station antenna usually requires dual-polarization operation with satisfactory input return loss, adequate dual-polarization isolation, stable gain, and half-power beamwidth (HPBW) in a wide bandwidth covering the entire or part of the mobile communication bands. Such comprehensive requirements provoke great challenges in antenna design. A novel design scheme is proposed by involving fragment-type structures (FTSs) in antenna and seeking for the optimal FTS by multiobjective optimization searching. The technique is demonstrated by improving crossed dipoles for operation in band ranging from 1.7 to 3.8 GHz. Part of the dipole arms can be gridded into cells and reconfigured by using FTS elements. For automatic optimization searching, a binary coding scheme for both the FTS distributions and canonical dipole structure dimensions is proposed. Simulation and measurement show that the optimal crossed dipole antenna may acquire a wide operation bandwidth of 76.3%, with the return loss higher than 15 dB, isolation higher than 30 dB, HPBW of 65° ± 5°, and gain of 9 dBi ± 0.65 dBi for ±45° polarizations. [ABSTRACT FROM AUTHOR]

This article describes a compact dual-polarized endfire antenna array for fifth-generation (5G) millimeter-Wave (mm-Wave) mobile application. The dual-polarized endfire antenna element is constructed by a compact open-ended cavity with cavity mode for vertical polarization (VP) radiation and open-slot mode for horizontal polarization (HP) radiation. With the integrated design of VP and HP elements, the proposed antenna shows a much more compact size compared to existing schemes. To enhance the bandwidth of low-profile VP radiation, a slot is etched on the cavity to create a new mode for dual-resonance response, realizing a wide bandwidth of 24.5–29.5 GHz for both polarizations. In addition, radiation pattern modification techniques are employed to achieve good endfire beams with a high front-to-back ratio for both polarizations, thus enabling a high peak gain of 10.3 and 11.3 dBi for VP and HP, respectively. A wide beam scanning range of ±50° with realized gain above 7 dBi is realized at 27 GHz for both polarizations. In virtue of compact size, wide bandwidth, high gain, and good spatial coverage, the proposed design strategy is promising for future 5G mm-Wave mobile phones. [ABSTRACT FROM AUTHOR]

A W-band low-profile dual-polarized Cassegrain reflectarray with an integrated feed is designed in this work. High isolation, which is necessary for the in-band full-duplex (IBFD) applications, is realized between two feeding ports corresponding to the orthogonal polarizations. The antenna is composed of two parts, i.e., the dual-polarized planar-array feed and the Cassegrain reflectarray with a small focal-length to diameter ratio ($F/D)$. The dual-polarized planar array feed is appressed behind the main-reflectarray, and the $F/D$ is reduced to 0.2 to realize the integration and the low-profile property. For the array feed, high isolation is achieved through the orthogonal-mode isolation and the differential signal cancellation. Its radiation pattern is also manipulated to fit the reflectarray considering the taper and spillover efficiency. For the reflectarray, the rotational symmetry configuration and the dual-layer-patch cell are applied to suit the dual-polarization operation and the large incident angle, respectively. The measured operation band, where the gain variation is within 1 dB, is 93.4–95.6 GHz. At the center frequency, the gains of the Cassegrain reflectarray for the two ports are 31.86 and 30.88 dBi, and the corresponding aperture efficiencies are 31.4% and 25.1%, respectively. The isolation between the two ports is higher than 55 dB within the operation band. This work is a low-profile candidate for W-band point-to-point IBFD communication. [ABSTRACT FROM AUTHOR]

A millimeter-wave (mm-wave) dual-polarization bidirectional multibeam array antenna based on substrate integrated waveguide (SIW) technology is presented in this article, which can generate 16 bidirectional radiation beams with two orthogonal linear polarizations. The proposed dual-polarization bidirectional multibeam array antenna, based on a new configuration, consists of two transverse slot array antennas (TSAAs), two longitudinal slot array antennas (LSAAs), and two dual-layer $8 \times 8$ Butler matrices (BMs). To realize dual polarizations, a new type of TSAA is designed and combined with a conventional LSAA. For the purpose of bidirectional radiation, two types of dual-polarization array antenna (DPAA), which are realized by combining different arrangements of the TSAA and the LSAA, is composited. In addition, a dual-layer $8 \times 8$ BM is developed, which can excite both the TSAA and the LSAA and generate dual-polarization bidirectional multibeam. Finally, the prototype of the planar dual-polarization bidirectional multibeam array antenna is fabricated, measured, and discussed. The measured results satisfactorily validate the simulated results. [ABSTRACT FROM AUTHOR]

In the following, we propose a dual-polarized double-layer metasurface lens based on split dipole unit cells. The characteristic mode analysis (CMA) of a split electric dipole shows two characteristic modes over the band of interest. By exciting these two modes with a certain phase difference, the reflection at normal incidence can be canceled. Inspired by this idea, a planar dual-polarized unit cell based on four pairs of split electric dipoles is designed on a single-layer substrate. A phase range of 396° and a transmission coefficient with a magnitude higher than 0.8 are achieved. For experimental verification, a metasurface lens with 36 × 36 elements is designed at 30 GHz with a focal diameter ratio of 0.84. The measured peak gain is 31.6 dBi at 31 GHz with an aperture efficiency of 45% and 1 dB/3 dB gain bandwidth of 7.3%/14%, respectively. Due to the dual-polarized operation, the relative high aperture efficiency, and the low-cost design, the proposed metasurface lens is a promising candidate for millimeter-wave communication, e.g., 5G and satellite communication systems. [ABSTRACT FROM AUTHOR]

In this letter, a compact ±45° polarized base station antenna array fabricated using laser direct structuring (LDS) technique is presented. The proposed antenna array operates in fifth-generation (5G) NR band 41 (2496–2690 MHz). The simple antenna elements of the array consist of a modified patch radiator fed by Y-shaped probes realized by injection molding, which are amenable to efficient mass production. An antenna unit (AU) is investigated to meet the specification requirements in practical base-station applications. A prototype of the AU was manufactured and measured, and the results showed that it is able to fulfill the design requirements within the operating band. These features also show that this LDS-based antenna array would be a promising solution for 5G base station applications. [ABSTRACT FROM AUTHOR]

This communication proposes a dual-polarized end-fire phased array for 5G handset devices at 28 GHz. The proposed four-element array has low profile of 1.1 mm, small clearance of 2.7 mm, and symmetric patterns in the vertical plane. The array element is fed by substrate-integrated waveguide (SIW), which works as a waveguide (WG) antenna with vertically polarized radiation pattern. Two transition plates are introduced to improve the impedance matching of the WG antenna. The horizontal polarization is generated by exciting one of the transition plates as an antenna. The other transition plate is modified as a group of triangle strips to minimize its reflection to the horizontal radiation patterns. A −10 dB frequency bandwidth of 5.3% and a −6 dB bandwidth of 25% are achieved, overlapping between the vertical and horizontal polarization. The array scanning angle is from −54° to 44° at 29 GHz for both polarization. Within the scanning range, the end-fire gain varies from 7.48 to 8.14 dBi for the horizontal polarization, whereas from 4.49 to 8.05 dBi for the vertical polarization. Good agreements between simulations and measurements are well achieved and shown in this communication. [ABSTRACT FROM AUTHOR]

A novel stacked antenna configuration is proposed for the designs of shared-aperture base station antennas. An antenna array consisting of a lower-band antenna element working in 690–960 MHz frequency band and four upper-band antenna elements operating in the 3.5–4.9 GHz band is designed to demonstrate the concept. In the proposed configuration, four upper-band antenna elements are placed over the aperture of the lower-band antenna. Four metallic sheets are introduced to provide capacitive loading for the lower-band antenna and simultaneously offer a ground plane for the upper-band antennas. Therefore, low-profile characteristic and high isolations between the dual-band antennas are guaranteed. The overall height of the antenna array is only $0.17\lambda _{\text {L0}}$ ($\lambda _{\text {L0}}$ is the free-space wavelength at the center frequency of the lower band), which is much lower than those of conventional designs. The measured results demonstrate that the designed antenna array achieves 32.7% and 33.3% impedance bandwidth in the lower and upper bands, respectively. High port isolations (>30 dB), high gains (>8 dBi), and stable radiation patterns are achieved in the two frequency bands. Owing to its simple structure and compact size, the resultant antenna array is easy for fabrication and is a promising candidate for sub-6 GHz band and 690–960 MHz band antennas. [ABSTRACT FROM AUTHOR]

This paper presents a novel dual-loop array antenna targeted at current and future base station applications. The antenna has four rectangular loops and four trapezoidal loops printed on the front and back sides, respectively, of a substrate placed above a flat square reflector. All eight loop radiators are excited simultaneously with properly designed feed networks to achieve its ±45° polarization states. The trapezoidal loops act like folded (electric) dipoles; the rectangular loops act primarily as magnetic dipoles. The combination of these two loop arrays leads to a type of magnetoelectric loop antenna that has stable directivity patterns with high cross-polarization discrimination (XPD) values across a 45.5% operational fractional bandwidth from 1.7 to 2.7 GHz. A fabricated and measured prototype confirms the simulation results and demonstrates that the half-power beamwidths in the horizontal plane vary between 63° and 70°, the XPD values are >20 dB in the boresight direction, and are >10 dB within the entire cellular coverage angular range: $-60^\circ \leq \theta \leq 60^\circ $. [ABSTRACT FROM AUTHOR]

This letter investigates the potential of additive manufacturing for the fabrication of complex antenna geometries with enhanced performance at K-band. Stereolithography is here used to three-dimensionally (3D) print a novel topology of dual-polarized leaky-wave antenna that allows for the control of its aperture illumination both in phase and magnitude. The antenna consists of a modulated triple-ridge square waveguide perforated on its top wall with crossed slots of different sizes. An orthomode-transducer is integrated within the structure for dual-mode operation. Monolithic implementation of this compound 3D structure is only possible thanks to additive manufacturing. In addition, low weight and compactness are attained compared to classical milling. The present proposal is validated through the manufacturing of a low-sidelobe-levels prototype suitable for intersatellite links. The corresponding measured results are in a very good agreement with full-wave predictions. [ABSTRACT FROM AUTHOR]

In this communication, a novel microstrip phased array with dual-polarized and wide-angle scanning in the 2-D space is proposed. The element antenna consists of a mushroom-shaped patch and two circular patches. Each circular patch is connected with one feeding port. The mushroom-shaped patch is excited via capacitive coupling through the gaps between the mushroom-shaped patch and the circular patch. The zeroth-order resonance and TM010 mode resonance are simultaneously generated in the mushroom-shaped patch. The 3 dB beamwidth of the element antenna in the 2-D space is in the range between 110° and 125°. One $6 \times 6$ phased array based on the antenna element is designed, fabricated, and measured. The phased array shows the dual-polarized wide-angle beam scanning in a range of ±66° in both $x {z}$ and $y {z}$ planes with the scan loss of 3.5 dB. [ABSTRACT FROM AUTHOR]

A novel dual-polarized antenna, with a large bandwidth and a high front-to-back ratio, is proposed in this communication. The antenna is composed of printed dipoles and tapered baluns above a square ground plane to yield a wide bandwidth. Semicylindrical walls are loaded on the edge of the ground plane to suppress the back lobe and produce a stable gain. Backward radiation is suppressed by the diffraction effect of the semicylindrical sidewalls. Simulation shows that the back-lobe level can be reduced below −13 dB in a large frequency range without degrading the antenna bandwidth. The proposed antenna is fabricated and the measured results show that it has an impedance bandwidth of 69.6% (1.46–3.02 GHz) for voltage standing wave ratio <1.5. Within the bandwidth, the gain varies between 7.1 and 8.4 dBi, and the front-to-back ratio is above 20 dB. The proposed antenna is suitable for outdoor base station applications, and the back-lobe suppression technique can be applied easily to base station antennas. [ABSTRACT FROM AUTHOR]

A new wideband differentially fed dual-polarized antenna with stable radiation pattern for base stations is proposed and studied. A cross-shaped feeding structure is specially designed to fit the differentially fed scheme and four parasitic loop elements are employed to achieve a wide impedance bandwidth. A stable antenna gain and a stable radiation pattern are realized by using a rectangular cavity-shaped reflector instead of a planar one. A detailed parametric study was performed to optimize the antenna’s performances. After that, a prototype was fabricated and tested. Measured results show that the antenna achieves a wide impedance bandwidth of 52% with differential standing-wave ratio <1.5 from 1.7 to 2.9 GHz and a high differential port-to-port isolation of better than 26.3 dB within the operating frequency bandwidth. A stable antenna gain ( $\approx 8$ dBi) and a stable radiation pattern with 3-dB beamwidth of 65° ±5° were also found over the operating frequencies. Moreover, the proposed antenna can be easily built by using printed circuit board fabrication technique due to its compact and planar structure. [ABSTRACT FROM PUBLISHER]

A ±45° dual-polarized base station antenna with a planar structure is proposed for 2G/3G bands. The +45° antenna and the −45° antenna share the same radiator, which is composed of four folded dipoles and four coplanar striplines. The coplanar striplines work as $\lambda $ /4 impedance transformers. Two Y-shaped feeding lines is designed to obtain a good impedance matching and a planar reflector is employed to achieve a stable radiation pattern. The antenna element has a wide impedance bandwidth of 27.8% with SWR < 1.5 (1.7–2.25 GH), and a stable radiation pattern and a high cross polarization discrimination (XPD) are also obtained across its operating frequency band. Also, an antenna array that consists of ten elements is developed for base station applications. The array is proposed for electrical downtilt and the downtilt angle is designed from 0° to 8°. The measured results show that a wide bandwidth of 30% (1.7–2.3 GHz), a great port-to-port isolation (>30 dB), a stable radiation pattern with 3-dB beamwidth 65° ± 5° in the horizontal plane, a high XPD and a high front-to-back ratio were achieved. [ABSTRACT FROM PUBLISHER]

This paper presents the design and measurements of a wideband dual polarized leaky lens antenna suitable for tightly spaced focal plane arrays. The antenna is composed of two crossed leaky slots fed by two orthogonal microstrips to realize the dual-polarization operation. The crossed microstrips are fed differentially in order to couple the radiation into the slots. The slots are then coupled to a dielectric lens to achieve directive patterns suited for feeding large Focal distance to Diameter ratio reflectors. In this paper, the proposed leaky lens antenna is optimized to achieve high aperture efficiency with clean symmetric patterns in both polarizations exceeding an octave bandwidth. The concept is validated by the measurements of the primary fields inside the lens and with GRASP simulations of the focal plane array. [ABSTRACT FROM AUTHOR]

We present a portable pattern-reconfigurable dual-polarized dielectric resonator antenna (DRA). Low-cost gallium arsenide (GaAs) single-pole, double-throw (SPDT) switches are utilized to select one of the feedline paths of the DRA, giving a boresight or cardioid pattern electronically. The measured results verify the proposed antenna switches its radiation patterns between cardioid and boresight shape, without significantly affecting its matching in the operating frequency range of 5-6 GHz. Results also confirm that the pattern configuration in one port with one polarization does not affect the RF characteristics of the other port with alternative polarization of the antenna. This two-port configuration makes the proposed antenna a suitable candidate for IEEE 802.11ac multi-user multiple-input-multiple-output (MU-MIMO) applications. [ABSTRACT FROM PUBLISHER]

In this letter, a dual-band and dual-polarization capacitive-fed slot patch antenna is investigated. The proposed antenna can operate at 1.575 GHz for Global Positioning System and 2.4 GHz for Wi-Fi system with the corresponding polarizations. A 90 ° hybrid coupler chip was used to excite the right-hand circular polarization required for optimum GPS performance. For the high frequency band, a pair of linearly polarized arc-shaped slots radiating at 2.4 GHz are embedded in the circular patch. The operating bandwidths of the antenna are enhanced by the multilayered geometry, and the capacitive disks feedpoints placed between the substrate layers. The measured impedance bandwidths at the lower and high bands are 320 and 230 MHz, respectively. The measured 3-dB axial-ratio bandwidth is 120 MHz. [ABSTRACT FROM PUBLISHER]

A dual-polarized dual-band (DPDB) microstrip antenna with two orthogonal feeding ports and similar-shaped radiation pattern is studied. The working mechanism of the dual-band operation and the similar-shaped radiation pattern is analyzed based on the S-parameters and the electric field distributions, respectively. A prototype shows that the measured impedance bandwidths for \textVSWR < 2 are 150 MHz (810–960 MHz, 17%) and 550 MHz (1690–2240 MHz, 28%) with mutual couplings of lower than - 32 and - 26\;\textdB at the lower and higher frequency bands, respectively. The antenna covers the GSM850/GSM900/GSM1800/GSM1900/UMTS bands for 2G/3G base station applications. Within the two frequency bands, the performance of similar-shaped radiation pattern, low cross-polarization, and stable gain is achieved. [ABSTRACT FROM PUBLISHER]

A broadband \pm 45^\circ dual-polarized base station antenna is proposed for 2G/3G/LTE bands. The proposed antenna has Y-shaped feeding lines to impart a wide impedance bandwidth to it, and a rectangular box-shaped reflector to enhance its stability in radiation patterns over the operating frequencies. A prototype of the proposed antenna is designed, fabricated, and tested. The measured results show achievement of impedance bandwidth of 45% for \ SWR<1.5 at both ports, port-to-port isolation >25 dB , a stable radiation pattern with 3-dB beamwidth 68^\circ\pm 2^\circ at H-plane and V-plane, and a stable antenna gain of 8.2 \pm 0.6 dBi from 1.7 to 2.7 GHz. A broadband dual-polarized antenna array with five elements for the band is developed for base station application. Measurements show achievement of array gain of 14.8 \pm 1.4 dBi, 3-dB beamwidth 66.56^\circ\pm 2.22^\circ at H-plane at port 1 and 64.85^\circ\pm 4.96^\circ at port 2 with \ SWR<1.5 over the operating frequency band. Simulation results have a good agreement with measurement ones. [ABSTRACT FROM PUBLISHER]

A compact dual-polarized double E-shaped patch antenna with high isolation for pico base station applications is presented in this communication. The proposed antenna employs a stacked configuration composed of two layers of substrate. Two modified E-shaped patches are printed orthogonally on both sides of the upper substrate. Two probes are used to excite the E-shaped patches, and each probe is connected to one patch separately. A circular patch is printed on the lower substrate to broaden the impedance bandwidth. Both simulated and measured results show that the proposed antenna has a port isolation higher than 30 dB over the frequency band of 2.5 GHz – 2.7 GHz, while the return loss is less than - 15~dB within the band. Moreover, stable radiation pattern with a peak gain of 6.8 dBi – 7.4 dBi is obtained within the band. [ABSTRACT FROM PUBLISHER]

A novel differentially-driven dual-polarized antenna is proposed in this communication. It is a magneto-electric dipole antenna whose gain and beamwidth keep constant along frequency within the operation bandwidth. If the antenna is ideally symmetrical, its differential port-to-port isolation is theoretically infinite. Due to the differentially-driven scheme, its cross-polarization level can be very low. Measurement shows that the proposed antenna achieves a wide impedance bandwidth of 68% (0.95 to 1.92 GHz) for differential reflection coefficients less than -10~dB and high differential port-to-port isolation of better than 36 dB within the bandwidth. The 3-dB-gain bandwidth of the proposed antenna is 62% (1.09 to 2.08 GHz), and the radiation pattern across it is stable and unidirectional. The broadside gain within the 3-dB-gain bandwidth ranges from 6.6 to 9.6 dBi. The cross-polarization level is lower than -23~dB across the 3-dB-gain bandwidth. The proposed antenna is the first differentially-driven dual-polarized magneto-electric dipole antenna. A feeding structure is specially designed to fit the differentially-driven scheme, and also to achieve wide impedance and gain bandwidths. [ABSTRACT FROM PUBLISHER]

A printed sectoral monopole antenna with ultra wide bandwidth has been proposed. This configuration is formed by chopping off a quarter part of a circular printed disc. The ultra wide bandwidth has been obtained in the frequency range from 1.84 to 11.82 GHz with dual polarization radiation patterns. The experimental and simulated results for this proposed antenna are presented, which are in agreement. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2066-2070, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27039 [ABSTRACT FROM AUTHOR]

Abstract: A wideband dual-polarized L-shaped printed monopole antenna (LSPMA) is presented. The antenna operates around the center frequency of 4GHz. This L-shape printed antenna provides wide impedance bandwidth over 4.7GHz. Experiments have been carried out to validate the simulated results of input impedance and dual polarized radiation patterns. [Copyright &y& Elsevier]

A new microstrip antenna element is presented in this article. The proposed antenna is suitable for integration into an array for satellite TV receivers. It has two metal layers only, which reduces its fabrication cost significantly in comparison with other antennas with more layers. The presented results show that the proposed antenna offers wide impedance bandwidth, high isolation between feeding ports, dual-polarization radiation, low cross-polarization level, and high radiation efficiency. A 2-by-2 array based on the proposed element is also presented in this article. Planar corporate feeding networks with new routing approach are used. The presented results of the new array show that it is suitable for use as a building block for a larger array which can repalce the parabolic dish reflector in satellite TV receivers. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 458–463, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24105 [ABSTRACT FROM AUTHOR]

A novel planar slot antenna is presented in this paper. The antenna provides dual-polarization and omnidirectional radiation patterns. Hence, it is suitable for hand-held equipments of wireless systems. The proposed antenna is optimized for operation at 5.2 GHz. The antenna, without ground plane extension, occupies an area of 2.17 × 2.17 cm². An impedance bandwidth of 10.6% is obtained, with a very good isolation between the two excitation ports. Appealing omnidirectional radiation patterns are maintained over the entire impedance bandwidth. The gains of the two polarizations are 2.59 and 3.52 dB, while the radiation efficiencies are 93% and 99.8%. [ABSTRACT FROM AUTHOR]