Dual-band Antenna Array Research Articles

Ku/Ka Dual-Band Dual-Polarized Shared-Aperture Beam-Scanning Antenna Array With High Isolation

This paper describes the design and realization of a Ku/Ka dual-band shared-aperture beam-scanning antenna array based on the concept of structure reuse. The antenna consists of four Ku-band linear antenna arrays implemented by the substrate-integrated waveguide (SIW) and four Ka-band linear antenna arrays. To increase the aperture utilization efficiency, the Ku-band antenna is employed as some sidewalls of the Ka-band antenna. Thanks to this compact topology, the element spacing at two frequency bands is able to meet the requirement of a wide-angle beam scan. Both feeding networks of these two arrays are designed by proper SIW power dividers through the printed circuit board fabrication process. In addition, the self-filtering characteristic of the antenna, the orthogonal polarization, and the optimal layout of the array are employed to ensure the high channel isolation between the two antennas operating at different frequency bands over the whole beam scan range. The isolation between antennas is better than 28 and 70 dB at the Ku-band and Ka-band, respectively, scanning up to even 40°. The proposed shared-aperture concept and the design results have been validated by the experimental results.

Design of Dual Band 5G Antenna Array with SAR Analysis for Future Mobile Handsets

This paper presents the design and specific absorption rate (SAR) analysis of the dual band antenna array for the future fifth generation (5G) mobile communication. The proposed antenna array operates in the Ka-band, at 28 and 38 GHz frequency bands. Roggers-5880 is used as a substrate having relative permittivity, thickness and loss tangent of 2.2, 0.254 mm and 0.0009 respectively in the proposed antenna array design. The main lobe gain of the single element 5G antenna is 7.71 and 7.73 dB at 28 and 38 GHz resonance frequencies correspondingly. As the gain requirement for 5G mobile communication system is 12 dB, thus 2 × 2 and 1 × 4 antenna arrays are designed to achieve the desired gain. The 2 × 2 antenna array yields a bore side gain of 12.3 and 15 dB, while 1 × 4 antenna array gives a bore side gain of 12.5 and 12.1 dB at 28 at 38 GHz frequency bands correspondingly. The dual band antenna (single element, antenna arrays) matched with a VSWR < 1.16 in the two frequency bands. All the simulations are carried out using computer simulation technology software. The SAR analysis averaged over 10 g of tissue of the proposed dual band 2 × 2 antenna array has been carried out on the head of human body using X-finite difference time domain electromagnetic simulation software, giving a safer limit of 0.37 and 1.34 W/kg < 2 W/kg according to the European IEC Standard at 28 and 38 GHz frequency bands correspondingly. The proposed antenna array is a suitable contender for the future 5G mobile handheld devices.

A Dual-Band MIMO Antenna With Enhanced Isolation for 5G Smartphone Applications

In this paper, a compact dual-band MIMO antenna array for 5G smartphone applications is proposed. The MIMO antenna consists of eight folded monopole antennas operating at 3.45-GHz band (3300~3600MHz). And the antenna elements with a size of $6.8\times 6.6\times4$ mm3 (about $0.078\lambda \times 0.075\lambda \times 0.046\lambda $ at 3.45 GHz), are disposed along each edge of the system circuit board. By introducing the decoupling structures, the isolation between inner antenna elements is improved from 10dB to 15.1dB in 3.45-GHz band (3300~3600MHz). Meanwhile the inner antenna units can generate an additional operating band covering 2400~2700MHz due to the coupling effect between the antenna elements and the proposed decoupling structures, which is promising for solving the problem of terminal space shortage. To verify the design principle of the proposed MIMO antenna array, the antenna is fabricated and measured. The measured results of efficiency and ECC are analyzed as well to demonstrate the performance of the proposed MIMO array. Channel capacity, user proximity and SAR analysis and are also given in this paper.

Dual-Band Performance Evaluation of Time-Modulated Circular Geometry Array With Microstrip-Fed Slot Antennas

This paper applies time modulation to deal with the design of dual-band antenna arrays in a circular geometry using a micro-strip-fed slot antenna as an element in the frequencies of 2.4 and 5.5 GHz. The motivation for this paper is to exploit the properties and advantages of time-modulated arrays in a dual-band scenario considering a circular geometry. This design considers the optimization of the time switched sequences of the antenna elements in the circular geometry for both operation frequencies. The design process to find the optimal switch- ON intervals of the circular array is carried out by means of the method of differential evolution and particle swarm optimization. The main contribution to the field of this paper is the dual-band performance evaluation of circular antenna arrays considering time modulation and measurements of the antenna element pattern. The performance evaluation and the results and discussion are achieved in terms of the radiation pattern with the measured antenna element, sidelobe level, sideband levels, switching times and efficiency.

A Low-Profile Coplanar Dual-Polarized and Dual-Band Base Station Antenna Array

This paper presents a low-profile coplanar dual-polarized dual-band base station antenna array. A slotted patch antenna operating from 0.82 to 0.99 GHz with four shorting strips is proposed and analyzed. The four shorting strips are employed not only to improve the impedance matching in the lower band but also to remove the center part of the patch, thus making room for higher band dipoles operating from 1.68 to 2.86 GHz. The height of the proposed array is nearly half of the conventional base station array while other performances are guaranteed. The measured results show that the proposed antenna array has wide impedance bandwidths of 18.7% (0.82–0.99 GHz) and 57.9% (1.68–2.86 GHz) (VSWR $0.109\lambda _{0}$ at 820 MHz). The measured gains are 13.8±0.5 dB and 16.7 ± 1 dB in lower and upper bands. Large front-to-back ratio (>24.6 dB) and high isolations (>30 and >25 dB in lower and upper bands, respectively) are achieved. The proposed antenna can be easily built with printed circuit board fabrication technique and applied in low profile multiband base stations for 2G/3G/4G and the next-generation systems.

Dual-Band Dual-Polarized Antenna Array With Flat-Top and Sharp Cutoff Radiation Patterns for 2G/3G/LTE Cellular Bands

This paper proposes a dual-band dual-polarized planar antenna array with flat-top and sharp cutoff radiation patterns for 2G/3G/LTE base stations. The array consists of $8 \times 8$ antenna elements arranged with nonuniform spacings and is assigned with optimized nonuniform excitations to achieve flat-top and sharp cutoff radiation patterns with low sidelobes. The radiating element consists of two square-shaped PCB boards. Extra adjustable coupling elements are introduced in the H-shaped patches to improve the impedance matching performance in an array environment as well as to reduce the size of the antenna element. In the 1.71–2.69 GHz band, the dual-polarized radiating element exhibits stable radiation patterns, excellent impedance matching (VSWR 40 dB). Frequency band selective variables are defined to group the antenna elements. They are optimized along with the element spacings and complex excitations in the optimizer to ensure stable flat-top radiation patterns. Rectangular-shaped baffles are introduced to reduce mutual couplings. A prototype of the $8 \times 8$ antenna array has been fabricated and measured. The results indicate that the proposed dual-band dual-polarized planar array achieves a half-power beamwidth of 50° ± 5° in both the H-plane and E-plane. The proposed antenna and its array exhibit attractive potentials for 2G/3G/LTE base station applications.

D esign of 8 × 8 dual‐band MIMO antenna array for 5 G smartphone applications

A dual-band 8 × 8 antenna array operating in the long term evolution (LTE) band 42 (3400-3600 MHz) and LTE band 46 (5150-5925 MHz) for 5G communication multi-input multi-output (MIMO) operation in the smartphone is presented. The proposed dual-band antenna array element is composed of an L-shaped open slot antenna and a U-shaped monopole antenna. The measured results exhibited acceptable isolation (better than 12 dB) and good efficiency (more than 50%) across the two desired operation bandwidths. In addition to that, the proposed antenna array has also shown good MIMO performances with envelope correlation coefficient (ECC) lower than 0.1, and ergodic channel capacities higher than 38.8 bps/Hz in the operation bands. The hand phantom effects are also investigated, and the results show that the proposed antenna array can still exhibit good radiation and MIMO performances when operating under the single hand mode (SHM) and dual hands mode (DHM).

A Compact Dual-Band Dual-Polarized Microstrip Antenna Array for MIMO-SAR Applications

This paper presents a compact dual-band dual-polarized microstrip antenna array with wide bandwidth and low profile for multiple-input multiple-output (MIMO) synthetic aperture radar- imagery applications where both high resolution and portability are required. This array has a stacked structure, consisting of two shared-aperture dual-band orthogonal-polarized sub-arrays with high isolation. Each pair of driven patches for the two-band shares two parasitic patches to achieve compactness. Slits are etched on the shared parasitic patches to adjust the coupling frequency between two elements of the two bands. The defected ground structure integrated in the array effectively suppresses H-plane cross-polarization. A $4\times6$ array as an MIMO element sized of 77 mm $\times79$ mm $\times2.2$ mm has been fabricated and tested. Both wide beamwidth and stable gain are achieved, where the impedance bandwidth of 27.7%, 30.6%, 15.6%, and 23.8% in X-band vertical, X-band horizontal, Ku-band vertical, and Ku-band horizontal polarizations, respectively.

Isolation Enhancement in Dual-Band Microstrip Antenna Array Using Asymmetric Loop Resonator

This letter presents the design of a wideband decoupling element for mutual coupling reduction in microstrip antenna arrays. The proposed decoupling unit cell consists of an asymmetric loop resonator with a coupled microstrip line for wide stopband characteristics from 2 to 5 GHz. The bandgap characteristic of the decoupling element is analyzed, and the results are presented. Furthermore, the resonator is deployed in a two-element dual-band microstrip antenna array, and mutual coupling reduction is demonstrated. The decoupling unit cell has a lateral dimension of 2.84 mm and hence enables the packing of antenna elements in very close proximity with reduced mutual coupling. The proposed solution offers additional isolation greater than 15 dB in a V-slot loaded dual-band antenna with edge-to-edge element spacing of ${\text{0.057}}\,\lambda _{o}$ . The prototype dual-band antenna array with decoupling element is fabricated, and the simulation results are validated using experimental measurements.

A Dual-Broadband Dual-Polarized Fylfot-Shaped Antenna for Mobile Base Stations Using MIMO Over-Lapped Antenna Subarrays

This paper proposes a novel design of a dual-broadband dual-polarized antenna for mobile communication base stations. The proposed antenna is Fylfot-shaped and covers 0.7–0.96 and 1.7–2.7 GHz simultaneously (with S11 ≤ −10 dB), which are the two common frequency bands for mobile communication systems. Three resonant frequencies are produced in the proposed design where two of them are independently controlled to achieve the dual-broadband performance. A prototype of the proposed antenna has been developed and tested. The results demonstrate that the antenna has high isolation between its ports, high polarization purity, and stable radiation patterns across both the frequency bands. A new linear array is proposed and implemented. Unlike reported dual-band base station antenna arrays, the proposed array uses a novel technique of two MIMO overlapped subarrays with shared radiating antenna elements. The overlapped subarrays have excellent frequency diversity performance with low envelope correlation coefficients. The array has been found to have the same performance as a standard conventional base station antenna but with 25% less number of antenna elements, which leads to a smaller size and lower cost. The simple antenna structure and the novel smart MIMO overlapped antenna subarrays technique give the design the privilege to be an ideal candidate for a low-cost directive base station antenna.

Implementation of Dual Band Antenna and Dual Band Antenna Array for WLAN Applications

Implementation of Dual Band Antenna and Dual Band Antenna Array for WLAN Applications

Electromagnetic coupling reduction in dual-band microstrip antenna array using ultra-compact single-negative electric metamaterials for MIMO application**Project supported by the National Natural Science Foundation of China (Grant No. 61372034).

In this paper, an ultra-compact single negative (SNG) electric waveguided metamaterial (WG-MTM) is first investigated and used to reduce the mutual coupling in E & H planes of a dual-band microstrip antenna array. The proposed SNG electric WG-MTM unit cell is designed by etching two different symmetrical spiral lines on the ground, and has two stopbands operating at 1.86 GHz and 2.40 GHz. The circuit size is very compact, which is only (where λ0 is the wavelength at 1.86 GHz in free space). Taking advantage of the dual-stopband property of the proposed SNG electric WG-MTM, a dual-band microstrip antenna array operating at 1.86 GHz and 2.40 GHz with very low mutual coupling is designed by embedding a cross shaped array of the proposed SNG electric WG-MTM. The measured and simulated results of the designed dual-band antenna array are in good agreement with each other, indicating that the mutual coupling of the fabricated dual-band antenna array realizes 9.8/11.1 dB reductions in the H plane, 8.5/7.9 dB reductions in the E plane at 1.86 GHz and 2.40 GHz, respectively. Besides, the distance of the antenna elements in the array is only 0.35λ0 (where λ0 is the wavelength at 1.86 GHz in free space). The proposed strategy is used for the first time to reduce the mutual coupling in E & H planes of the dual-band microstrip antenna array by using ultra-compact SNG electric WG-MTM.

Miniaturized dual-band antenna array with double-negative (DNG) metamaterial for wireless applications

A miniaturized dual-band antenna array using a negative index metamaterial is presented for WiMAX, LTE, and WLAN applications. This left-handed metamaterial plane is located behind the antenna array, and its unit cell is a combination of split-ring resonator, square electric ring resonator, and rectangular electrical coupled resonator. This enables the achievement of a metamaterial structure exhibiting both negative permittivity and permeability, which results in antenna size miniaturization, efficiency, and gain enhancement. Moreover, the proposed metamaterial antenna has realized dual-band operating frequencies compared to a single frequency for normal antenna. The measured reflection coefficient (S11) shows a 50.25% bandwidth in the lower band (from 2.119 to 3.058 GHz) and 4.27% in the upper band (from 5.058 to 5.276 GHz). Radiation efficiency obtained in the lower and upper band are >95 and 80%, respectively.

Dual-Band Base Station Array Using Filtering Antenna Elements for Mutual Coupling Suppression

This paper presents a novel dual-band base station antenna array using filtering antenna elements for size miniaturization. It consists of two $1 \times 6$ subarrays arranged side by side, which are designed for Digital Cellular System (DCS: 1710–1880 MHz) and Wideband Code Division Multiple Access (WCDMA: 1920–2170 MHz) applications. The two subarrays are composed of filtering antenna elements with high in-band radiation efficiency and out-of-band radiation rejection levels. The radiation of the DCS subarray is suppressed in the WCDMA band and vice versa. Mutual coupling between the two subarrays, therefore, can be suppressed and high isolation can be obtained with reduced subarray spacing. For demonstration, a dual-band filtering antenna array is designed and fabricated. The overall width of the array is only 206 mm, which is much narrower than that of typical industrial products ( $\sim 290$ mm). An isolation of 35 dB is obtained between the two subarrays without any decoupling network. The measured antenna gains are about 14.2 and 14.5 dBi for DCS and WCDMA bands, respectively, and the 3-dB beamwidths of the horizontal radiation patterns are 65° ± 5°. In addition, null filling below the main beam in the vertical radiation patterns is realized by elaborately designing a feed network to manipulate the output magnitude and phase of each array element. The proposed array is suitable for potential base station applications.

Scalable Multibeam Antenna Arrays Fed by Dual-Band Modified Butler Matrices

A concept of dual-band multibeam antenna arrays that allows for efficient utilization of a common aperture has been proposed. The presented antenna arrays allow for achieving $N$ -independent beams pointing at $N$ different directions at higher frequency and $N$ -independent beams at lower frequency pointing at $N/2$ different directions and having two orthogonal polarizations. As feeding networks, novel modified Butler matrices (BMs) have been proposed in which directional couplers having different properties in two frequency ranges have been for the first time utilized. To confirm the theoretical analysis, a dual-band multibeam antenna array fed by a modified $4\times4$ BM has been developed operating in 2.4 and 5.2 GHz frequency ranges.

Dual-Band Linear Antenna Array for Harmonic Sensing Applications

This letter presents the design and demonstration of a single-port dual-band linear patch antenna array operating at frequencies that are multiples of the fundamental frequency (12 and 24 GHz, for example in this demonstration) for harmonic sensing applications. The proposed antenna consists of a low-band serial feed patch antenna array and two high-band patch antenna arrays that couple to the feeding circuit over the high frequency band. In the low frequency band, the feeding circuit does not couple with the high band arrays. Simulated and measured results are presented to validate the proposed technique. The low-pass characteristics are demonstrated numerically. The measured reflection coefficients are lower than $-\hbox{18 dB}$ at the operating frequencies and the measured gains are higher than 13 dBi.

Beamforming and Angle-of-Arrival Estimation of Square Planar Antenna Array

This paper presents a dual-band planar antenna array for ISM band applications (2.4 GHz and 2.45 GHz). This antenna is proposed for indoor applications and enables adaptive beamforming and angle of arrival (AOA) estimation. An adaptive beamforming algorithm is applied for a planar antenna array, which is able to steer its main beam and nulls in azimuth and elevation planes over a wide frequency band. Planar antenna array operates as a spatial filter in 3D space, processing the received signals with weighting schemes. A planar antenna array is designed for AOA estimation in azimuth and elevation planes by using MUltiple SIgnal Classification (MUSIC) based on subspace algorithm. The Base Station (BS) equipped with this planar antenna is preferred to be at the center position on the room ceiling to cover all sectors of the room. It is designed to use four directional triangular elements arranged to form a square planar antenna array. Planar antenna with four elliptical slotted triangular elements (PAFESTE) is used to obtain optimal directivity in four directions in azimuth plane with specific orientation of 30? in elevation plane. It is characterized by half power beamwidth in elevation plane of about 60? and half power beamwidth in azimuth plane of about 90?.

A Dual-band and dual-polarized antenna array for 2G/3G/LTE base stations

A dual-band antenna array is proposed for the application of base station (BS) in 2G/3G/long term evaluation (LTE) mobile communications. This antenna consists of two independent ±45° dual-polarized arrays, one of which operates from 1.71 to 2.17 GHz, and the other of which is designed from 2.5 to 2.69 GHz. The proposed BS antenna array has a high isolation of greater than 29 dB and high front-to-back ratio of more than 26 dB at the operating frequencies. The measured peak gain is 17.9 and 18.1 dBi for the lower and upper bands, respectively, and the cross polarizations isolation (CPI)(within ±60o of the mainlobe) is 16 dB lower than the broadside co-polarization. It was confirmed that the proposed antenna array meets the communication standards in China. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:154–163, 2016.

A novel eight ports dual band antenna array for 2.4/3.5 GHz MIMO applications

An eight ports multiple-input multiple-output (MIMO) patch antenna array operating at 2.4GHz and 3.5GHz band is presented in this paper, which can be used for the Long Term Evolution (LTE), Microwave Access (WiMAX) and the low frequency band of Wireless Fidelity (WiFi). The presented antenna is fabricated on a F4B-2 substrate (ɛr=2.65, tanδ=0.002), it consists of four coplanar E-shaped patches which are orthogonal to each other. Two feed ports are respectively located at two adjacent sides of each patch. Double symmetrical slots are etched out in each patch to improve the antenna bandwidth, a 46mm×33mm metal parasitic patch is placed above each patch to improve the gain. The maximum gain of the proposed antenna array is more than 8dB at 2.4GHz band and 9dB at 3.5GHz band respectively.

Smart antennas for space-borne synthetic aperture radars

This paper discusses smart antennas for space-borne synthetic aperture radar (SAR). First, some recent development in smart antennas for space-borne SAR is reviewed. Then, the paper presents a low-cost space-borne SAR system using digital beam forming on receive. The smart antenna system is also discussed, and some results are shown. The antenna system, consisting of a parabolic reflector and multi-feed array, is designed and optimized for dual-band dual-polarized digital beam-forming performance. The operating frequencies are at X and Ka bands with the center frequency of 9.6 and 35.75 GHz, respectively. The stacked dipoles and square patches with parasitic elements are employed as the feed elements at X and Ka bands. Dual-band antenna arrays are combined in the same aperture, which not only reduce the aperture of the feed array, but also coincide the center of dual-band feed arrays.