Enhanced-Isolation Dual-Polarized Aperture-Fed Patch Antenna with Air Cavity for 5G Communication

In this paper, a novel dual-polarized patch antenna with extremely low-profile and compact structure is proposed for Sub-6 GHz 5G base station applications. The proposed antenna avoids using the conventional high-cost multilayer PCB technology, which makes it a low-cost design with a simple configuration. It consists of a radiation patch, a coupled feeding structure and a reflector. The compact size of the antenna can be achieved by etching T shape slots on the radiating patch. A square-ring shape feeding structure is introduced to couple the energy to the patch, achieving polarization of ± 45° and broadening bandwidth. As a result, the dual-polarized antenna could operate from 3.3 to 3.7 GHz with stable radiation patterns. Moreover, a 1 × 3 antenna array is designed and simulation results show that the antenna array could operate from 3.3-3.8 GHz with S 11 , S 22 less than -15 dB, high port isolation and stable radiation patterns. The proposed antenna has high potential in the 5G massive multiple-input multiple-output (MIMO) applications.

This paper presents a hybrid ring feeding dual-polarized patch antenna with high isolation in a wide working band. The proposed antenna consists of a circular radiating patch printed on the upper horizontal substrate, two pairs of Γ shaped strips printed on two vertical substrates, and a hybrid ring feeding network printed on the lower two horizontal substrates. The proposed antenna adopts Γ shape strips coupled feeding structure to achieve a wide operating band. Furthermore, a hybrid ring feeding structure with high isolation in a wide bandwidth, which is firstly proposed, is applied as feeding network. When one port is excited, the feeding network can realize twice the power cancellation. Thus, high ports isolation characteristics can be obtained. A prototype of the proposed antenna is fabricated and measured. Measured results show that the 10 dB reflection coefficient bandwidths of the two ports are both about 38.7%, with port isolation higher than 40 dB through most of the band, and the cross-polarizations are below −24 dB.

A dual-polarized patch antenna has been developed for n257 beam-forming application. A lot of 5G millimeter-wave applications require dual-polarized antennas that have broad bandwidth and broad beam-scanning range. Generally, a patch antenna needs thick substrate between the antenna and ground in order to achieve wide bandwidth, but it is difficult to feed such thick antenna by using vias. For example, an aperture coupled patch antenna fed by strip line through slot on ground is used [1] , where the ground is put between the feed line and the antenna. When an aperture coupled antenna is mounted on a radio module on the opposite side of which RF-IC is mounted, it is necessary to sandwich the feed lines by multiple grounds. This results in the increasing of the number of layers used for the antenna. To reduce the number of layers, a coplanar feed line is applied between the antenna and ground in our antenna. Figure 1 shows the design of the proposed antenna. It consists of two patch antenna layers, two coplanar line layers and a ground layer. The antenna size is 3×3 mm 2 that enables the antenna to be aligned at a half wavelength interval. Thickness between the coplanar line and the ground layer is 0.1 mm and that between the coplanar line and the antenna is 0.3 mm. Direction of the upper coplanar line is orthogonal to that of the lower one. In Fig. 1 , the upper layer line generates horizontally polarized radiation and the lower one generates vertically polarized radiation. As the coplanar lines cross slits on the ground, electromagnetic field is excited and coupled to the patch antenna.

A dual-polarized patch antenna array is proposed in this paper. The antenna is integrated in the module by the HTCC technology. The array element is a double-layer patch antenna with an air cavity. The air cavity reduces the equivalent relative dielectric constant of the substrate, and effectively extends the impedance bandwidth of the antenna. The proposed dual-polarized antenna array element achieves a wide fractional bandwidth (18.1%) and a port isolation over 16dB in the operating frequency band.

In this paper we present a novel dual-polarized patch antenna using two probe feeds for achieving high port decoupling. By using a thick air-layer substrate, which makes possible a wide impedance bandwidth. The two probe feeds have a short probe pin and a triangular transition patch (F.S. Chang and K.L. Wong, Microwave Opt. Technol. Lett. vol. 30, pp. 341-343, 2001), which makes good impedance matching over a wide frequency range very easy to obtain. In addition, an additional shorted inverted-L patch is added, which is for the purpose of decreasing the excited patch surface currents flowing from the excited port toward the other one, such that great improvement in port decoupling can be obtained. Details of the proposed design are described, and a prototype suitable for the dual-polarized WLAN base-station application at 2.45 GHz band (2400-2485 MHz) is constructed and studied.

To meet the urgent requirement for more channel capacity in modern wireless communication systems, antennas with more operation bands are demanded. However, large amounts of antennas suffer from low radiation gains and low port isolation levels. In view of this, a differentially fed, dual-wideband, dual-polarized patch antenna is proposed in this paper. Compared with conventional crossed-feeding structures, the proposed crossed dielectric resonator (CDR) can provide extra resonances with improved isolation levels and radiation gain. Further, four shorting pins are introduced to the radiating patch to help improve the impedance-matching performance. In addition, the proposed antenna also has a very compact size of 0.46λ × 0.46λ × 0.12λ. Finally, a prototype of the proposed antenna is fabricated to validate the design concept. The measured results show that the proposed antenna generates dual wide bands of 1.86–2.52 GHz and 3.26–3.72 GHz for |S11| < −10 dB. High radiation gains of 8.9 ± 0.9 dBi and 10.8 ± 1.2 dBi are also obtained, as well as high port isolation levels of better than 38.4 dB and 36.2 dB at the two bands. The excellent performance of the proposed antenna makes it a promising candidate for 4G/5G wireless communication systems.

A patch antenna with dual-band and dual-polarization operation is proposed and discussed. For feeding the antenna, it is used the electromagnetically coupled microstrip-T junction and coplanar waveguide (CPW)-line. Since both ports of the antenna are electromagnetically coupled, the proposed antenna eliminates the need for capacitors in the RF path for active antenna applications. By using CPW resonant cell, the demonstrated approach results in a significant improvement in port isolation.

Dual polarized patch antennas has many advantages such as low cost, low profile, easy fabrication and ease to integrate with circuits. In this paper, a novel design of a dual-polarized microstrip patch antenna along with Rectangular Dielectric Resonator Antenna (RDRA) operating at 4GHz is presented. The dual polarization in the patch antenna is achieved by introducing two ports with phase shift of 180° between them and the sides of the patch antenna are etched to improve the axial ratio. To further increase the gain RDRA is introduced, the RDRA is designed using Polyethylene material and optimized for dimension of $40\text{mm}\times 25\text{mm}$ to maintain the required axial ratio. The structure of dual polarized patch antenna and RDRA is simulated using EM flow solver ANSYS HFSS and the structure is fabricated as per the design specifications. There is a close agreement between the measured and simulated results. The peak gain has increased from 7.4dBi to 8.9dBi by placing RDRA. The measured Axial Ratio is greater than 50dB and return loss is −15dB for dual polarized patch with RDRA.

A compact broadband dual-polarized patch antenna operating from 1.71 to 2.69 GHz for multi-functional services is presented. It has the total size of 100×100×22 mm3 (0.74λ0×0.74λ0×0.16λ0). Four fork-shaped probes are used to feed a square patch antenna to enhance the impedance bandwidth. A pair of broadband 180°-baluns designed using metamaterial transmission lines (MM TLs) is used in the feeding network to deliver two signals with equal power and 180° phase difference over a broad bandwidth. With the use of the baluns, the dual-polarized antenna can achieve a compact size, good isolation between two ports and low cross-polarization. The antenna is studied and designed using computer simulation. The simulated results shows that the proposed antenna has an impedance bandwidth of 48% (S11≤−10 dB) within the entire operating frequency band, and an isolation over 38 dB. The cross-polarization levels in both the E- and H-planes are less than −30 dB within the main lobe of the radiation patterns.

A miniaturized dual-polarized patch antenna with differential feeding is proposed for base stations. The dual-polarized patch antenna is composed of a radiating patch with the shape of triangle bends and L-shaped stepped type slots, two pairs of mutually vertical inverted L-shaped probes and feeding networks integrated on a reflector. The proposed patch antenna achieves the impedance bandwidth (the voltage standing wave ratio (VSWR)<1.5) of 16.3% ranging from 3.33 GHz to 3.92 GHz covering C-band and port isolation higher than 28 dB. And more importantly, the size of the patch antenna is only <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.24\times 0.24\times 0.174\ \lambda_{0}^{3}$</tex> ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lambda_{0}$</tex> is the free space wavelength at center frequency). The realized gain is greater than 7.6 dBi with a stable radiation pattern over the whole working frequency band.

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

A new feeding structure for patch antennas is proposed in this paper. The feeding structure is formed by a double torsion coil (DTC) with one end electrically connected to the ground. The maximum stretch length of the coil is around half of the wavelength of the center frequency. The winding direction of the coil is reversed at the middle point of the coil. The DTC is able to produce two coaxial equivalent magnetic dipoles polarized in the same direction, which can not only excite the TM01 mode of a patch antenna but also create another resonance, leading to a wideband impedance bandwidth. The working mechanism is explained in this paper by physics intuition. To validate the new feeding structure, a linear-polarized and a dual-polarized patch antenna prototypes working in the 3.5 GHz band are designed, manufactured, and measured. It is found that the linear-polarized patch antenna can achieve a bandwidth of 25% standing-wave ratio (SWR < 2) and 9.5 dBi average gain with stable radiation patterns and low cross polarization over the impedance bandwidth. The new feeding structure has a high potential for wideband massive multiple-input and multiple-output (M-MIMO) arrays of 5G and future wireless communication systems.

Effects of finite ground plane on the isolation and radiation properties of a broad-band dual-polarized aperture-coupled patch antenna are experimentally investigated. The dual-polarized patch antenna has a thick air substrate for broad-band operation (>16% for both polarizations) and is excited by microstrip lines through two H-shaped coupling slots. Results show that by selecting suitable ground-plane dimensions, isolation between the two feeding ports can be greatly enhanced by about 10 dB, and the cross-polarization level in the E and H planes can also be improved by about 10 and 5 dB, respectively. Also, the impedance bandwidth increases with decreasing ground-plane dimensions.

A novel tuned loop feed for patch antennas is described. The arrangement provides a symmetrical excitation of the patch with a double tuned response with enhanced bandwidth. The tuned loop together with the patch can be seen as a band pass filter comprising a series resonator and parallel resonator tuned to the same frequency. The tuned loop can easily be implemented as a microstrip PCB. A dual polarized patch antenna can be designed for diversity reception using this technique. Measured results are given, showing that this feed is effective in broadening the bandwidth of patch antennas. This configuration is a good candidate for radiating elements in cellular base station antennas.

This paper presents a designed partially reflective surface (PRS) with a low-cost substrate for gain enhancement in the dual-polarized antenna. The conventional microstrip patch antenna, with the operating frequency at 3.5 GHz, is selected to use for a source. Two SMA ports with a 90-degree difference phase are fed into the patch antenna to create a dual-polarization. The PRS is designed based on the unit cell of a square metallic patch. The dimension of the unit cell is 5 mm × 5 mm. To investigate the performance of the PRS design, the fully 3D-simulation software, CST-Studio, is used to monitor all parameters, e.g., reflection magnitude, reflection phase, and realized gain. Four conditions on the square patch are carefully chosen by varying the dimension of the square patch from 3 mm to 4.5 mm with a step of 0.5 mm. Based on simulated results, the maximum gain at the zero degrees is increased from 1.68 dBi to 5.82 dBi, when compared with and without an integrated partially reflective surface.