Wideband Dual-polarized Antenna Research Articles

Differentially-Fed, Wideband Dual-Polarized Filtering Antenna With Novel Feeding Structure for 5G Sub-6 GHz Base Station Applications

In this paper, a differentially fed, wideband dual-polarized patch antenna with filtering response is proposed. A novel E-shaped feeding structure with one end shorted to the ground is proposed to excite a square patch antenna, and an extra resonant mode is induced, which leads to a wider operation band. Besides, symmetric open/short-circuited stepped impedance resonators (O/SCSIRs) are proposed to generate the third resonant mode. And the bandwidth is further improved. Moreover, the gain-suppression level outside the operation bands is greatly enhanced as the introduction of O/SCSIRs. A prototype of the proposed antenna is fabricated and tested. Measured results show that the proposed antenna has a wide operation band of 22.2% (3.12–3.9 GHz) for active VSWR $1\times 4$ liner array is also developed to validate our design. Good radiating performance of the proposed antenna makes it a promising candidate for 5G Sub-6 GHz base station applications.

A Wideband Dual-Polarized Dipole Antenna With Folded Metallic Plates

A wideband dual-polarized dipole antenna with fourfolded metallic plates is proposed in this letter. The folded metallic plates are vertically placed on the ground plane, under the dipole arms. Owing to the coupling with the nearby dipoles, an additional resonance beside the original impedance passband of the dipole antenna can be generated by the parasitic plates, leading to a very wide operating bandwidth. A prototype was fabricated and tested to verify the design. The measured results show that the prototype has a −10 dB impedance bandwidth of about 92%, a port isolation of over 20 dB, and an average gain of 6.2 dBi within the operating band.

Wideband dual-polarized Vivaldi antenna with improved balun feed

AbstractThe paper researches a kind of wideband dual-polarized Vivaldi antenna with improved balun feed which consists of slot line and two bent coplanar strip lines. The whole of antenna structure is composed of two orthogonal Vivaldi antenna elements, and the mode of feeding adopts electromagnetic coupling from micro-strip line to slot line. The improved balun can avoid the intersection of transmission lines, reduce the size, and simplify the assembly. The electromagnetic simulation and optimization design of proposed antenna are carried out by using electromagnetic simulation software, CST. Simulation results show that the isolation between two polarized ports is more than 15 dB within working frequency range of 2–3.5 GHz and VSWRs of two ports are lower than 2.5 at the range of 2–3.5 GHz. The designed antenna is fabricated and measured. The measured results indicate that the designed antenna achieves anticipated patterns and feasible design of the dual-polarized Vivaldi antenna. The dual-polarized Vivaldi antenna with improved balun feed is suitable for some application fields, such as passive electronic reconnaissance, passive radar, and wideband communication and detection.

Bandwidth Enhancement of a Dual-Polarized Slot Antenna Using Characteristic Modes

In this letter, a wideband dual-polarized slot antenna is presented. The proposed antenna is designed in a systematic way using the theory of characteristic modes for slot apertures. An H-shaped slot in an infinite ground plane is used as the initial structure for further optimization design. Magnetic characteristic currents for the first four modes of the slot are investigated. To enhance the bandwidth (BW) of the antenna, the geometry of the slot antenna is then modified based on the clear physical insights obtained from the modal analysis. In addition, two pairs of differentially fed capacitive coupling elements are introduced to excite the first two modes of the slot, and an integrated wideband feeding network is designed. An antenna prototype in WLAN 2.4 GHz band is fabricated. Experimental and simulated results show that the proposed dual-polarized slot antenna has a wide BW and good dipole-like radiation characteristics. Compared with the initial H-shaped slot antenna, the BW of the proposed antenna is enhanced from 17% to 46%. The measured port isolation over the entire frequency band is about 26 dB, and the cross-polarization level is over 28 dB for the two polarizations.

Design of High-Isolation Wideband Dual-Polarized Compact MIMO Antennas With Multiobjective Optimization

Multiobjective optimization design of compact multiple-input and multiple-output (MIMO) antennas with canonical structures (viz., transformation or combination by regular shapes) for wideband radiation and fragment structures (viz., combination by discrete fragment patches) for high isolation is proposed and demonstrated. In the design, multiobjective evolutionary algorithm based on decomposition combined with differential evolution (MOEA/D-DE) for optimization of canonical structures and MOEA/D combined with genetic operator (MOEA/D-GO) for optimization of fragment structures are combined and iterated. The design is demonstrated with compact bow-tie MIMO antennas sharing a small common ground plane. The four orthogonally deployed bow-tie antennas are optimized by using MOEA/D-DE to acquire dual polarization and wideband radiation. Fragment-type structures on the common ground plane are optimized by using MOEA/D-GO to acquire very high isolation. Both simulation and measurement show that the optimized MIMO bow-tie antennas provide isolation higher than 30 dB in a relative bandwidth of 40% (from 2.6 to 3.9 GHz). With the proposed design technique, dual-band high-isolation MIMO antennas may also be designed.

A wideband dual-polarized patch antenna fed with the aperture-coupled microstrip

ABSTRACTIn this paper, a compact broadband dual-polarized stacked patch antenna with the aperture coupled microstrip feed is proposed. By adding a parasitic disc patch, the bandwidth is effectively broadened. Meanwhile, to improve the isolation at the low frequency band, a rectangular slot is etched along the diagonal line of the ground plane. The measured results show that the proposed antenna can operate from 9.6 to 22.4 GHz and the relative bandwidth is 80%. Also, the isolation within the operating frequency band is better than 15 dB and the maximum gain reaches 4.08 dBi.

A Wideband Dual-Polarized Omnidirectional Antenna for Base Station/WLAN

A wideband dual-polarized omnidirectional antenna is proposed for mobile communication base station and 2.4 GHz wireless local area network applications. An integrated design is achieved by combining an inverted-cone monopole for vertical polarization (VP) and a modified cross bow-tie dipole for horizontal polarization (HP). The proposed antenna has a compact size because the HP element acts as the HP radiating element and the ground plane for the VP element simultaneously. The proposed VP and HP antennas are excited by a $50~\Omega $ Sub-Miniature-A connector and a broadband feeding network, respectively. The overall volume of the proposed antenna is only $0.35\lambda _{0}\times 0.35\lambda _{0}\times 0.25\lambda _{0}$ (with $\lambda _{0}$ being the wavelength of the lowest frequency). Simulation results show that the dual-polarized omnidirectional antenna achieves a bandwidth (for $\vert \text{S}_{11}\vert dB) of about 41.5% (1.64–2.5 GHz) with an isolation of at least 25 dB and the gain variations at the center frequency in the horizontal plane are 0.7 dB for VP and 2.3 dB for HP. The good agreements between the simulation and measured results validate the proposed design.

A Wideband Dual-Polarized Antenna Using Shorted Dipoles

A novel design method of a wideband dual-polarized antenna is presented by using shorted dipoles, integrated baluns, and crossed feed lines. Simulation and equivalent circuit analysis of the antenna are given. To validate the design method, an antenna prototype is designed, optimized, fabricated, and measured. Measured results verify that the proposed antenna has an impedance bandwidth of 74.5% (from 1.69 to 3.7 GHz) for VSWR < 1.5 at both ports, and the isolation between the two ports is over 30 dB. Stable gain of 8–8.7 dBi and half-power beamwidth (HPBW) of 65°–70° are obtained for 2G/3G/4G base station frequency bands (1.7–2.7 GHz). Compared to the other reported dual-polarized dipole antennas, the presented antenna achieves wide impedance bandwidth, high port isolation, stable antenna gain, and HPBW with a simple structure and compact size.

Compact Wideband Dual-Polarized Antenna With High Isolation Using Modified Direct Feeding Structure For Indoor Beamforming Array Applications

A modified direct feeding structure is proposed in this paper to realize a compact ( $45 \times 45$ mm2) wideband dual-polarized antenna with high isolation (33 dB) and low cross-polarization (30 dB). Compared with the conventional crossed dipole antennas, two additional pairs of dipoles are employed as coupling baluns as well as radiators. As a consequence, the proposed antenna with more symmetrical structure has the advantages of both the direct feeding (DF) and the coupling feeding (CF) structures, such as, balanced matching, high isolation, low cross-polarization, and compact size. Besides, the gap structure between adjacent dipoles is designed in elliptical shape to further improve the impedance matching. The proposed antenna realizes a wide impedance bandwidth over 51% (1.7–2.85 GHz) for VSWR <1.5. It is worth mentioning that the compact size and high isolation could greatly reduce the element spacing of beamforming antenna array. In order to investigate the performance of beamforming array, a two-element array fed by the out-of-phase power divider network is developed. The lowest operating frequency can be further extended to 1.6 GHz and the cross-polarization discrimination (XPD) is more than 10 dB within ±60° of the main lobe.

A High-Gain Transmitarray for Generating Dual-Mode OAM Beams

This paper proposes a novel transmitarray antenna which can achieve high gain and produce dual-mode orbital angular momentum (OAM) beams in Ku -band. Two back-to-back wideband dual-polarized microstrip antennas are employed as the unit cells, which are connected using metalized via holes. Full 360° phase ranges can be obtained by varying the length of feeding lines in two orthogonal polarizations. Due to high isolation between the two orthogonal polarizations, dual-mode OAM beams can be formed simultaneously by tuning phase distributions in x- and y-polarizations, respectively. The approach for generating OAM beams is explained. To verify this concept, one prototype carrying 0 and +1 mode OAM beams is designed, fabricated, and measured. Experimental results demonstrate that both 0 and +1 mode OAM beams can be generated successfully, and the measured results agree well with the simulated results. Because of high directivity and focusing effects of transmitarray, the proposed +1 mode OAM beam has stable performance at a long propagation distance. The maximum gain reaches 26 and 20 dBi in 0 and +1 mode OAM beams, respectively. Meanwhile, a narrow divergence angle of ±5° is obtained in +1 mode OAM beam. Compared with other OAM antennas reported, main advantages of the proposed antenna include high gain, narrow divergence angle, low cost, planar structure, and the capability of producing dual-mode OAM beams.

Extremely low-profile wideband dual-polarized microstrip antenna for micro-base-station applications

Extremely low-profile wideband dual-polarized microstrip antenna for micro-base-station applications

A Wideband Dual-Polarized Antenna With Two Independently Controllable Resonant Modes and Its Array for Base-Station Applications

A wideband dual-polarized antenna with two independently controllable resonant modes for 2G/3G/4G bands is proposed. Its radiator mainly consists of two crossed stepped-width loop dipoles loaded with two crossed straight dipoles. Two approaches are adopted to design the proposed antenna with large freedom. First, by replacing the traditional uniform-width loop dipole with a stepped-width one, the first resonant mode can be adjusted independently by controlling the width ratio of the loop. Second, a pair of crossed straight dipoles are embedded into the gap of the crossed loop dipoles, and the second resonant mode can be controlled independently by altering the length or position of the straight dipoles. Measurements show that the antenna achieves an impedance bandwidth of 54.5% with VSWR< 1.5 (1.68–2.94 GHz) and isolation of greater than 28.5 dB within the bandwidth. Also, an antenna array with ten elements is developed with electrical downtilt from 0° to 8° for practical base-station applications.

A Multimode Wideband ± 45$ ^{\circ}$ Dual-Polarized Antenna With Embedded Loops

A wideband dual-polarized antenna is proposed for base station applications. Compared to the conventional crossed loop dipole antennas, additional loops are embedded into original loops to generate a new resonant mode. Therefore, a multimode antenna with an enhanced impedance bandwidth is completed. A prototype of the proposed antenna is designed, fabricated, and tested. The measured impedance bandwidth of two ports is 51% with Return Loss > 15 dB from 1.68 to 2.83 GHz, and the isolation between two ports is greater than 27 dB. The measured results also show that a stable radiation pattern with 65.4o ± 2.4 $ ^{\circ}$ half-power beamwidth in the horizontal plane for slant 45 $ ^{\circ}$ polarization and a stable gain of 8.8 ± 0.7 dBi are achieved from 1.7 to 2.7 GHz.

A Wideband Dual-Polarized L-Probe Antenna Array with Hollow Structure and Modified Ground Plane for Isolation Enhancement

A two-element wideband dual-polarized L-probe antenna array with hollow structure is presented in this letter. The hollow structure is applied to offer space for hosting other antennas (e.g., the concept of shared-aperture antenna). Each radiating element is designed with a compact size of 51 mm × 51 mm × 24.5 mm (0.374λ 0 × 0.374λ 0 × 0.18λ 0 at 2.2 GHz) and has a hollow volume of 31 mm × 31 mm × 24.5 mm. With a slotted square ring patch and unique L-probes, the antenna element exhibits a fairly large fractional bandwidth of 45%, ranging from 1.71 to 2.69 GHz. Moreover, a narrow slot and T-shaped metallic structures on the ground plane are introduced to increase the input-port isolation of the proposed antenna array to 26 dB across the entire operating bandwidth. The experimental results indicate that the antenna array has an average realized gain of 10.5 dBi, which correlates well with the simulations.

A Compact Wideband Dual-Polarized Slot Antenna With Five Resonances

This letter presents the design and analysis of a compact dual-polarized slot antenna using a triple-mode stepped slot-line resonator and a dual-mode cross-shaped monopole. The orthogonal polarization is achieved by feeding the two ports symmetrically at the opposite positions of the slot. All the five resonance frequencies can be flexibly adjusted by tuning different dimension parameters, so by increasing the frequency difference between the five resonance modes, a very wide common operating band (1.63-2.93 GHz) is obtained and also with a high port isolation (<; -32 dB). Finally, by loading two grounded lumped capacitors on the cusp sections of the monopole, its second resonance frequency can be independently reconfigured.

A Wideband Base Station Antenna Element With Stable Radiation Pattern and Reduced Beam Squint

This paper presents the design procedure, optimization strategy, theoretical analysis, and experimental results of a wideband dual-polarized base station antenna element with superior performance. The proposed antenna element consists of four electric folded dipoles arranged in an octagon shape that are excited simultaneously for each polarization. It provides ±45° slant-polarized radiation that meets all the requirements for base station antenna elements, including stable radiation patterns, low cross polarization level, high port-to-port isolation, and excellent matching across the wide band. The problem of beam squint for beam-tilted arrays is discussed and it is found that the geometry of this element serves to reduce beam squint. Experimental results show that this element has a wide bandwidth of 46.4% from 1.69 to 2.71 GHz with ≥15-dB return loss and 9.8 ± 0.9-dBi gain. Across this wide band, the variations of the half-power-beamwidths of the two polarizations are all within 66.5° ± 5.5°, the port-to-port isolation is >28 dB, the cross-polarization discrimination is >25 dB, and most importantly, the beam squint is <4° with a maximum 10° down-tilt.

A Wideband Dual-Polarized Antenna for LTE700/GSM850/GSM900 Applications

A novel resonator-loaded wideband dual-polarized antenna is proposed for LTE700/GSM850/GSM900 applications. Four single-polarized miniaturized antenna elements are placed with square arrangement upon the reflector for dual polarization. One pair of parallel elements is for +45° polarization, and the other pair is for –45° polarization. The impedance bandwidth is greatly improved loaded with a resonator. Experimentally, the antenna exhibits a wide impedance bandwidth of 37.5% ranging from 0.67 to 0.98 GHz for | $S$ 11|<–15 dB, high isolation of more than 40 dB, and stable gain of around 9.5 dBi over the whole operating band.

A wideband gain-enhanced dual-polarized printed antenna based on log-periodic parasitic directors (LPPDs)

A novel wideband and high gain dual-polarized antenna with log-periodic parasitic directors is presented in this paper. The antenna is composed of two cross printed dipole antennas vertically fixed on an aluminum plate as ground plane, which are excited by two similar micro-strip baluns. In order to further improve the gain with a broad bandwidth, the log-periodic parasitic directors are loaded on the printed dipole antennas innovatively. Measured results show that the proposed antenna achieves a –10 dB return loss with bandwidth of 1–2.1 GHz (71%), and its port isolation is higher than –20 dB within that band. Furthermore, the average gain of antenna is improved by 3 dB because of LPPDs.

Design of a wideband dual-polarized microstrip patch antenna with novel structure for WLAN application

This article presents the design of a novel structure to increase bandwidth of single layer dual-polarized microstrip patch antenna using metallic cone on top of the patch antenna. The antenna is fed by two orthogonal 50Ω microstrip feedlines using λg/4 transformers. Tunable stubs are employed along the quarter-wavelength transformer to optimize the antenna's impedance match. Results confirm the parasitic cone mounting provides significant bandwidth enhancement. The antenna was fabricated, and a good agreement is achieved between measurement and simulation. The measured results show that the antenna achieves a −10 dB impedance bandwidth of 29% and isolation of >22 dB between the two input ports across its operating bandwidth (4.8–6.44 GHz) with low cross polarization level of <20 dB. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1599–1602, 2016

Design of a dual-polarized wideband antenna for 2G/3G/4G mobile communication base station application

A wideband dual-polarized antenna for 2G/3G/4G mobile communication base station systems is presented in this article. The proposed antenna is composed of two pairs (four) of metal sheets as the main radiation elements. Downward stubs at the end corners of the metal sheets are used to reduce the size of the antenna and for the convenience of tuning. Cylinder with slots is placed at the center of the antenna as balun. Cable is used for the feeding and part of the outer conductor is removed for tuning. An antenna prototype was fabricated. The measured results show that a bandwidth of 53% (1.70–2.95 GHz) for VSWRs < 1.5 is obtained for both polarization ports, which can cover the 2G/3G/4G mobile communication frequency band (1.71–2.69 GHz). The isolation between two ports is larger than 28 dB and the radiation patterns of the antenna are stable over the entire operating frequency band (1.71–2.69 GHz). © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1329–1332, 2016