Planar MIMO Research Articles

Efficient High Gain Elliptically Polarized Phased MIMO Antenna

A phased MIMO antenna with a coaxial feed is designed to operate in the electromagnetic spectrum with the frequency range of 8 GHz to 12 GHz, which resonates at 9 GHz, is used in military and satellite communication. The ability of phased MIMO antennas to change the form and orientation of the radiation pattern without constantly moving the antenna is unique. The proposed approach can also improve radiation efficiency by maximizing array unit size. To validate the proposed method, an elliptical polarization phased antenna has been constructed as a planar array. A 2 to 2 planar dual polarized MIMO antenna is intended to improve the efficiency. The obtained return loss for 2x2 planar MIMO is -19.34 dB. The proposed 2x2 MIMO antenna is projected on a teflon material with dielectric constant of 2.25 and the thickness of the substrate is 7mm. The efficiency for two port MIMO antenna is 97.7%.

Multi-standard planar compact 4-port MIMO with enhanced performance for ISM/5G NR/C/WLAN/X band applications

In this research, a compact 4-port Multiple-Input-Multiple-Output (MIMO) antenna with dual band is proposed for 5 GHz Wireless Local Area Network (WLAN) and 5 G New Radio (NR) sub-6 GHz n77/n78/n79 band applications. An identical element is used for designing MIMO antenna and each element is excited by coplanar waveguide (CPW) feed technique. To achieve low mutual coupling among the antenna's elements along with compactness of presented MIMO antenna, a top ring resonator is shorted with the ground plane using strip line. It can resonant in the range from 1.9 GHz to 3.6 GHz and from 4.2 GHz to 11.6 GHz, respectively and isolation is achieved with level − 18 dB. Also, equivalent circuit model of proposed MIMO design is analyzed. The overall size of proposed four element MIMO antenna is only 30 × 30 × 1.6 mm3. The designed antenna is fabricated on FR-4 substrate and measured results well matched the simulated results. Also, MIMO parameters for diversity performance check is analyzed and studied and shows good applicant for multiple applications in wireless technology such as UMTS/LTE/Wi-Fi/WLAN/ISM/5 G cellular communication/sub-6 GHz/X- band.

Compact 4-port planar MIMO antenna with enhanced isolation for WLAN/WiMAX applications

Compact 4-port planar MIMO antenna with enhanced isolation for WLAN/WiMAX applications

Wideband Low-Profile 8 × 8 MIMO Antenna Based IFA Pair for Ultrathin 5G Smartphones

In this paper, a wideband 8 × 8 MIMO antenna is proposed. The proposed antenna can realize the low profile of 4 mm and the 3.18–4.40 GHz broadband coverage only by adjusting the ground edge structure of the deformed inverted-F antenna. Based on the original antenna, the 5G new radio (NR) band n77 (3.3–4.2 GHz) can be covered without adding any structure. In addition, the coupling between the antenna elements has also been improved, decreasing from −9.7 dB to −13.37 dB. A dual-element IFA pair is simulated, fabricated, and measured, the results show the bandwidth of 3.07–4.43 GHz, and the isolation of −13.89 dB can be achieved. An eight-element MIMO antenna is formed by placing four sets of antenna pairs along the two long edges of the substrate. The experimental results show that the bandwidth is 3.18–4.40 GHz, the isolation between any two ports is better than −12.25 dB, and the total efficiency is 61.14%–93.97%. By placing the planar antenna vertically, the ground clearance of the antenna can be reduced to zero, and the performances are similar to the planar MIMO antenna. The proposed MIMO antenna has a good profile and efficient radiation performance compared with the other works, so it has an important application value in ultrathin 5G smartphones.

Design and Performance Analysis of a Compact Planar MIMO Antenna for IoT Applications.

This article presents a quad-band multiple-input-multiple-output (MIMO) antenna for the Internet of Things (IoT) applications. The proposed antenna consists of four quarter-wavelength asymmetrical meandered radiators, microstrip feed lines, and modified ground planes. The antenna elements are arranged in a chiral pattern to improve isolation between them, with two radiators and two ground planes placed on the front side of the substrate and the other two on the back side. The MIMO antenna has an operating bandwidth (S11 ≤ −10 dB) of 1.76–1.84 GHz, 2.37–2.56 GHz, 3.23–3.68 GHz, and 5.34–5.84 GHz, covering GSM, WLAN, WiMAX, and 5G frequency bands. The isolation between the radiating elements is greater than 18 dB in the operating bands. The peak gain of the antenna is 3.6 dBi, and the envelope correlation coefficient (ECC) is less than 0.04. Furthermore, the proposed antenna is validated for IoT-based smart home (SH) applications. The prototype MIMO antenna is integrated with a commercially available ZigBee device, and the measured values are found to be consistent with the expected results. The proposed MIMO antenna could be a good candidate for IoT systems/modules due to its low profile, compact size, lightweight, and easy integration with wireless communication devices.

Miniaturized self-isolated UWB MIMO planar/cuboidal antenna with dual X-band interference rejection

The work presents two configurations of four-port UWB MIMO antenna designs with dual notched features. Firstly, a planar four-port UWB MIMO antenna (Design-1) of dimension 31.5 × 34 × 0.8 mm3 is designed by placing four F-shaped radiators over the FR4 substrate board orthogonally. Further, to achieve band-notched characteristics at 7.3 GHz and 8.2 GHz, a pair of mushroom EBG structures and a folded U-shaped slot are positioned over the substrate layer coupled to the feedline and above the radiator, respectively. Secondly, a four-port cuboidal MIMO antenna (Design-2), of dimension 20.8 × 20.8 × 19 mm3 is designed to exhibit band-notched characteristics within the same frequency bands (7.3 GHz and 8.2 GHz). The performance parameters for these designs including the envelope correlation coefficient (ECC) and the diversity gain (DG), are also evaluated and compared. ANSYS HFSS V14.0 tool is used for simulating the designs. For validation purposes, the two prototypes are fabricated and characterized. The measured results are found to be very close to their simulated counterparts.

A compact 4-element printed planar MIMO antenna system with isolation enhancement for ISM band operation

In this research, a small 4×4 printed Multiple-Input/Multiple-Output (MIMO) antenna for use in Industrial, Scientific, and Medical (ISM) systems with medical applications is presented. The proposed structure consists of four dragonfly-shaped radiators and four stepped-ground planes. In this design, adjacent elements are placed perpendicular to each other to create the necessary isolation between them. Also, a novel decoupling-element is utilized between the radiating-elements as an innovation for enhancing the isolation. A pair of rectangular-shaped slits on either side of the dragonfly-shaped radiation patch is employed for determining the frequency band of the antennas. Laboratory results show that the proposed MIMO antenna can cover the frequency band of 2.16 GHz to 3.2 GHz with isolation above 21.4 dB. Small dimensions of 0.63λ×0.63λmm2 and presentation of diversity performance with an Envelope Correlation Coefficient (ECC) of less than 0.001 for aligned elements and 0.00043 for orthogonal elements are other particular advantages of the proposed antenna.

Cordate-shaped UWB-MIMO antenna with notch band characteristic and high isolation

PurposeThis paper aims to design a most demanding low profile and compact ultra-wide band (UWB) antenna system for various wireless applications. The performance (in terms of data rate) of UWB system is improved by using multiple-input-multiple-output (MIMO) technology with it. Owing to the overlap of other existing licensed bands with that of UWB, electromagnetic signals can interfere. So, notched band UWB MIMO antenna system reported here which is highly compact, bandwidth efficient, superior data rate and high inter-element isolation comparatively to other reported designs.Design/methodology/approachA 49 × 49 × 1.6 mm3 quad-port UWB MIMO antenna with specific bandwidth elimination property is designed. The proposed planar MIMO configuration comprises unique four identical “Cordate-shaped” monopole radiators fed by 2.3-mm thick microstrip-lines. The radiators are located right-angled to each other to enhance inter-element isolation. Further, a different approach of slitted-substrate is applied to minimize the overall size and mutual coupling of the MIMO antenna, as a substitute of decoupling and matching structures. The defected ground structure is used to obtain −10 dB impedance bandwidth in entire UWB band, without compromising with the lower cut-off frequency response. Further, to eliminate the undesired resonant band (WLAN at 5.5 GHz) from UWB, a rounded split ring resonator is introduced in monopole patch.FindingsIn the entire operating band of 2.8 to 11 GHz, isolation among elements is more than 24 dB, envelope correlation coefficient less than 0.002, diversity gain greater than 9.99 dB and TARC less than −7 dB are obtained at all 4-ports.Research limitations/implicationsThe measured parameters of the fabricated prototype antenna on FR4 substrate are found in good agreement with the simulated results. The small variation in software results and hardware results are observed due to hardware design limitations.Practical implicationsThe proposed design may be used for any wireless application following in the range of UWB.Originality/valueIt can be shown from graphs of measured parameters of the fabricated prototype antenna. They found to be in good agreement with the simulated results.

Meander-line electromagnetic bandgap structure for UWB MIMO antenna mutual coupling reduction in E-plane

This paper presents an ultrawideband (UWB) meander-line electromagnetic band gap structure for mutual coupling reduction in E-plane of MIMO antennas operating in the frequency range 3.1–10.6 GHz. Planar UWB MIMO antenna with edge to edge gap of 8 mm has been designed and fabricated on FR4 substrate with dielectric constant 4.4 and height 1.6 mm. An array of four unit cells of electromagnetic bandgap structures arranged in top and bottom layers of the substrate connected through vias has been placed in between antennas to achieve the reduced mutual coupling in the ultrawideband range. Minimum 1 dB and maximum 14 dB reduction in mutual coupling is achieved for 3.4–8 GHz frequency range. Minimum 8 dB and maximum 24 dB mutual coupling reduction is achieved for range of 8–10.6 GHz. Measured results and surface current of MIMO antennas also validate the mutual coupling reduction. Envelope correlation coefficient (ECC) less than 0.02 and channel capacity loss (CCL) less than 0.5 bps/Hz are achieved.

3-D Short-Range Imaging With Irregular MIMO Arrays Using NUFFT-Based Range Migration Algorithm

3-D imaging with irregular planar multiple-input-multiple-output (MIMO) arrays is discussed. Due to signal acquisition on irregular spatial sampling grids by using these antenna arrays, the fast Fourier transform (FFT)-based imaging algorithms cannot readily be used for image formation. To avoid the application of computationally intensive coherent summation algorithms such as filtered backprojection or Kirchhoff migration, we propose a nonuniform FFT (NUFFT)-based MIMO Range Migration Algorithm (i.e., NUFFT-based MIMO-RMA) for efficient microwave imaging. The algorithm exploits NUFFT to reconstruct the wavenumber–domain spectra related to each Fourier frequency. It is generic and applicable to 3-D imaging with irregular planar MIMO arrays. The effects of irregular spatial sampling and signal bandwidth on the imaging performance and computational efficiency of the proposed algorithm are analyzed. Finally, some numerical simulations and experimental results are presented to demonstrate the performance of the proposed imaging algorithm.

Integration of 5G Rectangular MIMO Antenna Array and GSM Antenna for Dual-Band Base Station Applications

In this paper, a dual-band dual-polarized antenna array is presented for 5G base station application. The developed antenna array consists of a $4\times 4$ planar MIMO array operating at 3.3-5.0 GHz band (upper band UB) and a single antenna element working at 0.69-0.96 GHz band (lower band LB). The dual-band operation is based on our previously proposed antenna topology. The novelty of this paper is that the UB antenna array is a large-scale rectangular lattice array with 16 antenna elements for practical MIMO applications. Meanwhile, both the cross-band and in-band mutual coupling among the LB and UB antennas are furtherly suppressed by employing three decoupling techniques including rectangular ring resonator, ferrite chock ring, and novel baffle structure. With these decoupling technologies, the UB antenna array and the LB antenna are successfully integrated within a compact volume of $0.93\lambda _{L} \times 0.93\lambda _{L} \times 0.17\lambda _{L}$ ( $\lambda _{L}$ is the wavelength at 0.82 GHz). Experimental results show that the proposed dual-band antenna array offers high cross-band port isolation (>30 dB). Stable radiation patterns are also achieved for both the LB and UB antennas with averaged gain of 8.6 dBi and 7.3 dBi, respectively. The radiation efficiency is higher than 90% across the entire operation bands. It is the first time to realize a large scale sub-6 GHz MIMO antenna array shared-aperture working with a GSM band antenna element in a such compact volume.

MINIMAL PLANNER MOBILE PHONE MIMO ANTENNA WITH ENHANCED GAIN

Background. Previously, Many MIMO designs were presented for 4G applications. Out of stated 4G MIMO antennas, few designs presented are not suitable for use in mobile phones due to their large size as compared to the standard sizes of current generation mobile phones. The rest, Ceramic based mobile phone antenna and a multi-band MIMO antenna with PIFA structures have significant heights and non-planner structure which makes them unsuitable for mobile phones as they are getting thinner with advancement in technology. Some MIMO antennas were designed with simpler structure and suitable size but they do not have adequate bandwidth. Here there is a need to develop a MIMO system with an adequate bandwidth to cover all 2G, 3G and 4G bands as well as compact to be suitable for mobile communication.Objective. The purpose of the paper is to design a compact planner MIMO antenna Suitable for Mobile communication with enhanced gain and an enhanced bandwidth to cover all 2G, 3G and 4G bandsMethods.i. A monopole was designed with proper dimensions, which was designed to operate at focus recurrence of 1.8GHz. That covers the wide scope of data transfer capacity from 1.1 GHz to 2.7 GHz at -9 dB reference line. Then an inverted L shape structure known as SIR stub technique is used to enhance the bandwidth.ii. The inverted L shape structure which is extended from the ground plane is put around the monopole which generates the low resonant frequencies and also broadens the bandwidth. Bandwidth is broadened to 0.8 GHz to 3.5 GHz.iii. For the purpose of more impedance matching, a small patch is etched from the ground plane opposite to the feeding and all the parameters are optimizedResults. that lower 0.9GHz radiation pattern is omnidirectional while at higher frequencies it is quasiomnidirectional, a steady gain greater than 2.8dBi over the entire frequency band i.e from .8 GHz to 3.5 GHz, avery high gain of 6.7 dBi at 0.9 GHz. The compact wide band planar MIMO antenna has over 80% efficiency over most of the working recurrence For handy application ECC value less than 0.5 is adequate for mobile phones. The measured ECC is less than 0.36 over complete operating frequency band, which is all right for mobile phonesConclusions. The paper presents compact planner two port MIMO antenna with wideband width and high gain. The proposed antenna achieved a wide bandwidth from 0.8GHz to 3.5GHz covering 2G/3G/4G bands and Wi-Fi (2.45GHz). High isolation between antenna elements, lower ECC and high diversity gain makes the design of the compact planner wide band MIMO antenna a suitable possibility for mobile phone applications.

Design and Development of Low Profile MIMO Antenna for 5G New Radio Smartphone Applications

A low-profile planar four-element MIMO antenna is proposed in this paper that can be integrated inside wireless handheld devices. Every unit antenna is made of simple planar L-shaped monopole placed over etched non-ground area of 10 × 5 mm2. The optimized antenna elements cover three 5G New Radio bands falling within C-band: n77 band (3.3–4.2 GHz), n78 band (3.3–3.8 GHz) and n79 band (4.4–5 GHz), with isolation better than 18.8 dB, without the requirement of any additional decoupling structure. The designed antenna is fabricated on FR4 substrate of dimension 120 × 65 × 1.6 mm3. Antenna characteristics regarding reflection coefficient, mutual coupling, radiation pattern and gain are measured and discussed. The envelop correlation coefficient is computed and is lower than 0.018 for the entire range of frequency under consideration. The simplicity and compactness of the proposed MIMO antenna provides adequate space for integration of other circuits inside handheld mobile terminal. Further the integration with lower generation antennas are investigated; the result indicates that the placement of the proposed antenna system on the two long arms of ground plane offer adequate space for integration of lower generation antenna without adversely affecting each other’s performance.

An Optimized Planar MIMO Array Approach to In-Air Synthetic Aperture Sonar

Modern three-dimensional (3-D) imaging sonar sensors are perfectly capable of creating awareness of the complete nearby environment with great accuracy. However, as range increases, these systems start to struggle with object detection as the poor attenuation of sound through air causes the signal-to-noise ratio to become too small. When looking at other sensing modalities, such as radar, this problem is tackled by using systems that utilize more than one element in the sending and/or receiving stage resulting in a greater effective detection range. At this further distance, the resolution of the obtained image will tend to decrease. Both radar and underwater sonar systems make use of synthetic aperture systems to increase the spatial imaging resolution. In this letter, we combine both techniques to create an in-air (simultaneous transmit) synthetic aperture beamforming (STSTAB) sensor, based on the eRTIS 3-D sonar sensor, that will increase the system's range and angular resolution without sacrificing the measurement rate. Different aspects of the emitter array will be addressed, such as the optimal placement of the elements of the emitter array, along with the coded signals that will be emitted simultaneously. The result will be a fast-measuring imaging sonar sensor with a narrow point-spread-function and improved range.

Design and Implementation of a Planar MIMO Antenna for LTE-Applications

Design and Implementation of a Planar MIMO Antenna for LTE-Applications

Omega-K Algorithm for Near-Field 3-D Image Reconstruction Based on Planar SIMO/MIMO Array

The characteristics of the range cell migration (RCM) under single-input-multiple-output (SIMO) bi-static geometry are studied and an omega-K algorithm for near-field 3-D imaging based on planar SIMO or multiple-input-multiple-output (MIMO) array is proposed. The RCM and the linear part of the range offset (RO) within SIMO data are corrected by employing a 3-D Stolt transformation. The residual range error is further compensated by phase multiplication and an image-domain interpolation. Reconstruction for a MIMO aperture can be achieved by adding together all the focusing results from its SIMO subarrays. The implementation details of the algorithm are described. The imaging resolution and the sampling requirements for a MIMO aperture are discussed. Since the RO correction is achieved by an approximate way, the spatial limitation for accurate reconstruction is also given. The imaging accuracy and the high efficiency of the algorithm are demonstrated both by simulations and experiments with various distributed targets based on planar MIMO arrays. Real-time 3-D imaging for planar SIMO/MIMO aperture is expected to be achieved by using the algorithm.

Offset planar MIMO antenna for omnidirectional radiation patterns

An offset quad element multi-band planar MIMO antenna with omnidirectional radiation patterns is proposed for nonline of site (NLOS) communication on low-cost FR-4 dielectric substrate for 4G and future technologies. A 1 × 2 power divider arm results in dual beam and enhances diversity parameters and omnidirectional radiation patterns. Moreover, the MIMO antenna limits the proximity/coupling effects using a T-shaped isolator and achieves more than 12.4 dB of isolation between the radiating ports. The proposed design covers WLAN/WiMAX bands with gain and radiation efficiency of more than 2.6 dBi and 71%, respectively, in 2:1 VSWR bands of bandwidths 16.39% (2.24-2.64 GHz) and 7.88% (3.41-3.69 GHz). The −10 dB impedance bandwidth is more than 280 MHz in each band. An ECC level of ≤ 0.01 has been achieved in the whole band.

Planar UWB MIMO Antenna With Pattern Diversity and Isolation Improvement for Mobile Platform Based on the Theory of Characteristic Modes

This communication presents a planar ultra-wideband multi-input multi-output antenna with pattern diversity and isolation improvement based on the theory of characteristic modes. The proposed antenna (for new-generation wireless mobile terminals) consists of two ultra-wideband antenna elements—a compact quarter loop and a circular planar monopole located on the opposite edges of a rectangular ground plane. These two antenna elements are able to excite different modes in the ground plane and thus realize the desired diverse radiation patterns and high isolation without any additional decoupling structures. The experimental results show that both antenna elements are ultra-wideband with impedance bandwidths (return losses more than 6 dB for the quarter-loop antenna and more than 10 dB for the circular planar monopole antenna) of 130% (2–9.5 GHz). The isolation is over 20 dB with a peak value of 50 dB. The realized gains are above 1.5 dBi. The total efficiencies are above 70%. The envelope correlation coefficient is less than 0.03 assuming that the antenna operates in an isotropic channel.

Compact Ultra‐Wide Band MIMO Antenna System for Lower 5G Bands

This paper presents a novel compact 2 × 2 planar MIMO antenna system with ultra‐wide band capability. Antenna system is specifically designed to target lower 5th generation operating bands ranging from 2 GHz to 12 GHz. This band also covers the IEEE 802.11 a/b/g/n/ac. The antenna array geometry has been simulated using CST MWS. The design is extremely miniaturized with total structure size of 13 × 25 × 0.254 mm3. The simulated and measured results have been presented. Measured and simulated return loss values for designed antenna are less than −10 dB over the operating band and lowest values of −35 dB and −32.5 dB can been seen at 5.2 GHz and 9.2 GHz, respectively, whereas at the center frequency the return loss is −25.2 dB. The mutual coupling between both elements is less than −20 dB over the transmission bandwidth. Simulated and measured radiation patterns in E and H planes at center frequency show nearly isotropic far fields. The maximum gain is measured as 4.8 dB. Promising results of Envelope Correlation Coefficient and gain diversity of the design have been achieved. Simulated and measured results are found in good agreement. The fractional bandwidth of antenna is measured as 143.2% which satisfies its ultra‐wide band response.

A 5G MIMO Antenna for Broadcast and Traffic Communication Topologies Based on Pseudo Inverse Synthesis

This paper proposes a new design of a dual-polarized base station antenna for sub-6-GHz 5G communication covering the band from 3.3 to 3.8 GHz. The proposed antenna offers a good impedance matching across the desired frequency band with $\text {VSWR} \le 1.5$ , a stable radiation pattern with a half power beam width of 65° ± 5°, and a high isolation between the ports with a small size and a low profile. The antenna is converted to a planar MIMO antenna array with low envelop correlation coefficients between the array elements to perform in either a broadcast or traffic communication topology whenever required. In the broadcast communication topology, the proposed MIMO antenna array covers a sector of 65° in the horizontal plane with three different down-tilted beam directions at 0°, 10°, and 20° in the vertical plane as conventional base station antennas used for 2G, 3G, and 4G. In traffic topology, the proposed MIMO antenna array can direct multiple beams to concurrent multiple users in a point-to-multipoint communication based on a novel pseudoinverse synthesis (PIS). The novel PIS is proved to be better than the other approaches which use spatial or frequency diversity as it possesses the advantage of the spatial diversity (by using a single frequency for multi-user coverage) and the advantages of the frequency diversity (by offering good steering capability and high directivity for each user). It is capable of radiating dynamic multiple beams simultaneously with an excellent flexibility and steering capability in real-time processing and outperforming other multi-beam antenna array methods. Thus, this new design is an ideal candidate for the new 5G mobile base stations.