Compact,Isolation Enhanced,Band-Notched SWB–MIMO Antenna Suited for Wireless Personal Communications

Herein, a Conductor Backed Co-Planar Waveguide fed, compact, slotted Multiple–Input–Multiple–Output or MIMO antenna having Super Wideband (SWB) response and tunable band-notching feature is presented. In addition, an improved method for cut-off frequency prediction of the antenna is formulated. A super wide frequency response from 01.21 to 34.0 GHz and notches at Wireless Local Area Networks or WLAN bands (04.92–05.83 GHz) and Worldwide Inter-operability for Microwave Access or WiMAX bands (03.30 GHz–03.70 GHz) are obtained. By fine tuning the dimensions of the Split Ring Resonator Structure introduced in the radiating element, band-notched characteristics centered at 05.50 GHz WLAN band is obtained. A second band notch having centre frequency at 03.50 GHz for the WiMAX band is obtained by the introduction of a Spiral Microstrip Defected Structure in the feeding segment. The antenna is 20?×?36?×?1 mm³ in dimension. Acceptable gain all through the functional bandwidth, excepting the notched bands makes the MIMO antenna a novel contender for SWB operations particularly for Wireless Personal Communications.

     

可用于物联网的高隔离度双频MIMO天线

设计了一种高隔离度双频多输入多输出（MIMO）天线,该天线覆盖2.4 GHz和5 GHz无线局域网频带,可以应用于移动物联网之中。天线包含两个相同的辐射单元天线,采用微带馈电的方式进行馈电。单元天线使用单极子天线作为基本辐射器,其包含一根长的和短的单极子天线,分别谐振在低频和高频频段。通过在两个单元天线中间加载T型隔离器提高了单元天线之间的隔离度。天线的辐射振子、馈电以及T型隔离器都印刷在同一块微波板材上,从而方便了天线的制作和加工。仿真结果表明,该天线在1.9~2.8 GHz以及4.7~6.2 GHz频带范围内能实现良好的双频工作特性,天线隔离度近20 dB,可以广泛应用于物联网系统中。     

A Compact UWB and Bluetooth Slot Antenna for MIMO/Diversity Applications

A novel compact pattern diversity slot antenna for ultra‐wideband (UWB) and Bluetooth applications is presented. This antenna consists of two modified coplanar waveguides that feed staircase‐shaped radiating elements, wherein two different fork‐like stubs are placed at the 45° axis. The measured results show that this proposed antenna operates from 2.3 GHz to 12.5 GHz, covering Bluetooth, WLAN, WiMAX, and UWB. The performance of radiation patterns and the corresponding envelope correlation coefficient prove this antenna is suitable for MIMO/diversity systems. Also, the antenna's compact size makes it a good candidate for portable devices.     

具有双陷波特性的UWB-MIMO天线

提出了一款具有双陷波特性的紧凑型超宽带多输入多输出(ultra wideband multiple-input multiple-output, UWB-MIMO)天线. 天线由两个辐射元件组成,整体尺寸为41 mm×25 mm×1.6 mm. 通过在天线的接地平面中引入两个叠加的T型结构获得良好的隔离度;同时,通过在天线上刻蚀C型槽和U型槽实现双陷波特性,有效抑制了无线局域网(wireless local area networks, WLAN)和X波段通信卫星的干扰;并从表面电流分布的角度分析了陷波原理. 实验结果表明:所设计的MIMO天线的阻抗带宽为2.8~13.4 GHz,两个陷波频带分别为4.8~5.94 GHz和6.9~8.23 GHz;在整个工作带宽内,隔离度大于15 dB. 说明MIMO天线具有良好的辐射特性、稳定的增益和较低的包络相关系数(envelope correlation coefficient, ECC)(<0.1),适用于UWB-MIMO系统应用.     

A compact four‐element MIMO antenna for WLAN/WiMAX/satellite applications

This paper presents a four‐element wideband monopole MIMO antenna. Initially, a single‐element wideband CPW‐fed antenna is designed operating in the range of 4.30 to 6.45 GHz. Using this design, an approach towards MIMO structure is studied. A two‐element structure is designed keeping them adjacent to each other, and the isolation between the antennas is observed. After which, a four‐element structure is designed having the best orientation in order to achieve good isolation between the antenna elements. The proposed antenna configuration has four identical CPW‐fed elements. The proposed configuration has a fractional bandwidth of 40.27% and has a simulated peak gain of 5.5 dBi. This antenna is intended to be used for WLAN, WiMAX, and satellite bands of range corresponding to 4.70–6.19, 5.5–5.7, and 5–6 GHz. All the necessary antenna simulations are simulated using Ansys HFSS and verified on NI AWR Design Environment. The fabricated model of the proposed design is measured for its performance parameters and validated.     

多用途双频双极化双通道MIMO 室内基站天线

多输入多输出(Multiple Input Multiple Output,MIMO)天线是MIMO技术的关键,现代无线通信领域的迅速发展对MIMO天线提出了许多新的要求.该文利用微带天线的低剖面特性,采用双线馈电的方式实现了两款双端口的MIMO天线,其中一款基于正方形辐射贴片,两个端口都工作于2.4GHz并且具有相同的辐射特性;改变贴片的尺寸可以得到另一款双频MIMO天线,分别工作于2.4GHz和3.5GHz,可以同时覆盖LTE(Long Term Evolution)、WiMAX(Worldwide Interoperability for Microwave Access)频段与WiFi(Wireless Fidelity)的部分频段,该天线的最大增益可达8dB,并且两个端口对应两个互相垂直的极化,满足室内基站的需要.     

Design of novel compact eight-element lotus shaped UWB-MIMO antenna with triple-notch characteristics on hollow substrate

The design of novel compact two-element and eight-element lotus shaped multiple-input-multiple-output (MIMO) antenna system employing pattern diversity with enhanced isolation characteristics is presented. The proposed two-element antenna system is arranged rotationally on a square-hollow substrate resulting in an eight-element MIMO antenna system employing pattern diversity. The developed eight-element MIMO antenna system resonates in the frequency range 3.1 to 14.6 GHz housing the complete UWB band with triple band-notch characteristics at 3.7–4.5 GHz (C-band satellite down link [3.7–4.2 GHz]), 5.1–5.9 GHz (WLAN) and 6.8–8.25 GHz (X-band satellite down link (7.25–7.75 GHz) and up link (7.9–8.4 GHz)) bands. The antenna system gives element-to-element isolation of more than 25 dB in the majority of the operating band with a peak gain of 6.8 dBi and a maximum 90% efficiency. The important MIMO metrics like ECC (envelope correlation coefficient), DG (diversity gain), total active reflection coefficient (TARC), channel capacity losses (CCL) and MEG (mean effective gain) are presented for both two-element and eight-element to estimate the performance the proposed antennas in multi-antenna environments. The both two- and eight-element designs are fabricated and the measured results of those are well agreed with simulation results.     

Miniaturized six-ring elliptical monopole-based MIMO antenna for ultrawideband applications

This paper proposes a miniature two-element Multiple Input Multiple Output (MIMO) antenna dedicated to UWB applications. The proposed MIMO design has a very low profile of 30 × 20 × 1.6 mm³. The proposed antenna is carefully designed and optimized using HFSS simulation software. As a proof of concept, the proposed design is realized and experimentally tested for MIMO applications. The proposed structure, printed on an FR4 substrate, comprises two symmetrical elliptical conductive patches on the upper side and a modified ground plane on the lower one. Each radiating element includes six elliptical rings. The modified ground plane consists of a T-shaped strip and two semielliptical slots etched opposite the feed line. All the parameters of the design are carefully optimized to achieve an ultrawide bandwidth antenna spanning from (136.08%) 3.1 to 16.3 GHz. The results are discussed and analyzed in terms of bandwidth, gain, efficiency, radiation pattern, diversity gain, envelope correlation coefficient (ECC), total active reflection coefficient (TARC), and mean effective gain (MEG). All simulated results are found to be in good accordance with experiments. The design reveals attractive features for UWB applications. A good isolation (17 dB) between the two radiators is achieved despite the close proximity using the suggested ground plane geometry.     

Design of Compact Quad-Band Notched UWB-MIMO Antenna

With quad-notched band characteristic, a compact ultra-wideband (UWB) multiple-input-multiple-output antenna is proposed in the article. There are two identical monopole elements in the system. By inserting symmetrical L-shaped slots, complementary split-ring resonators) and C-shaped stubs in each element, four notched bands are achieved to filter 3.5 GHz WiMAX, 5.25 GHz lower WLAN, 5.8 GHz upper WLAN, and 7.5 GHz X-band. Without decoupling structures, the antennas were placed vertically to obtain high isolation. Results indicate that the antenna operates from 2.6 to 13 GHz except four rejected bands, and port isolation (S21) is better than ?25 dB, envelope correlation coefficient is below 0.002 in UWB spectrum frequency of 3.1–10.6 GHz.     

Novel miniaturized folded UWB microstrip antenna‐based metamaterial for RF energy harvesting

This paper presents a design of an ultra‐wideband (UWB) cylindrical metamaterial (MTM) antenna for radio frequency (RF) energy harvesting to suit the fields of Internet of Things (IoT) applications. The patch circuitry is based on 3×5 Hilbert‐shaped MTM unit cells array to enhance the antenna bandwidth. While, the antenna ground plane is defected with an electromagnetic band gap structure to enhance the gain. The antenna is mounted on a polytetrafluoroethylene cylindrical substrate of an outer diameter of 15 mm and length of 32 mm with 1 mm in thickness. The substrate relative permittivity is 2.04, and the loss tangent is 0.0002. The antenna patch and the ground plane structures are printed with silver nanoparticles ink using a ^2.5D CNC plotter machine. The fabricated prototype provides an UWB over the frequency range from 3.77 up to 13.89 GHz with a first separate resonant mode at 3 GHz. The antenna performance is tested numerically using two different software packages of CST MWS and HFSS. Then, an experimental validation is conducted to realize the performance of the proposed antenna in harvesting the RF energy. Excellent conversion efficiency, about 90%, is achieved at 5.8 GHz. Finally, the antenna radiation patterns and S₁₁ spectrum are measured and compared against their simulated results to achieve good agreements.     

一种面向5G通信的宽带8单元MIMO天线设计

提出了一种面向5G的宽带8端口多输入多输出（multiple-input multiple-output,MIMO）天线.天线单元采用多枝节单极子结构,能够激发多模态,且能覆盖多频段.同时,采用弯折结构来实现小型化,且在相邻单元之间设计T形突出地结构来提高隔离度.仿真和实测结果显示,该天线在3~7.1 GHz内回波损耗大于10 dB,在3.3~7.1 GHz内隔离度高于15 dB.因为进行了有效的去耦,天线体现出明显的辐射分集特性,天线在目标sub-6 GHz频段内的包络相关系数（envelope correlation coefficient,ECC）接近0.在一8×8 MIMO系统中,计算得到的峰值遍历信道容量为43 bps/Hz,达到传统2×2 MIMO上限值的3.74倍.该8单元MIMO天线具有良好的分集和复用能力,能满足5G通信在sub-6 GHz的高速数据传输需要.     

一种加载磁电超表面的宽带多频贴片天线

利用磁电超表面概念通过在等腰直角三角形天线贴片和接地面上分别蚀刻周期互补开口谐振环和十字缝隙图案并将天线对应的地板位置截取掉一部分分别构建了单元1和单元2,分析了其左手特性和提高高频端增益的工作机理,最终加载单元2制作了一款宽带多频贴片天线。仿真结果表明,所提出的天线具有4个带宽并且能够覆盖2.4/5.2/5.8 GHz的蓝牙/RFID/WLAN和2.5/3.5 GHz的WiMAX频带,这4个频带的带宽分别是0.29 GHz（2.33~2.62 GHz）,1.01 GHz(3.11~4.12 GHz),0.39 GHz(4.97~5.36 GHz),0.41 GHz(5.74~6.15 GHz)。由于接地板上蚀刻的超材料结构的左手特性影响了天线介质基底的等效媒质参数, 天线电磁场的传播方向被改变,在高频端,天线辐射场主要集中在水平方向而不是传统贴片天线的垂直方向。     

Compact body-worn MIMO antenna with high port isolation for UWB applications

This article investigates the mutual coupling reduction of a compact two elements wearable ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna. The ground plane of the proposed wearable MIMO antenna structure consists of three connected square ring-shaped stubs and two rectangular slots of narrow height. These ground stubs and slots minimize the mutual coupling effect between antennas and provide high isolation. The suggested MIMO antenna functions from the 1.87 to 13.82 GHz frequency spectrum covering WLAN (2.4–2.484 GHz), UWB (3.1–10.6 GHz), and X band (8–12 GHz) with 152.32% fractional bandwidth. It sustains port isolation above 27 dB throughout the 2 to 13.82 GHz frequency band. Inside the whole working frequency band, the suggested antenna offers a tiny envelope correlation coefficient (ECC < 0.098), greater diversity gain (DG > 9.93 dB), minimum channel capacity loss (CCL < 0.32 bits/s/Hz), and slight magnitude variation in mean effective gain of antenna ports (< 0.1 dB). The recommended antenna yields a SAR level below the designated threshold (<1.6 W/kg), affirming its suitability for body-worn applications. The designed MIMO antenna structure has an overall volume of 32 × 48 × 1.5 mm³.     

Broadband sub-6 GHz flower-shaped MIMO antenna with high isolation using theory of characteristic mode analysis (TCMA) for 5G NR bands and WLAN applications

A small size neutralization line integrated flower-shaped MIMO antenna is designed and analyzed for sub-6 GHz type 5G NR frequency bands like n79 (4400–5000 MHz), n78 (3300–3800 MHz), n77 (3300–4200 MHz), and WLAN (5150–5825 MHz) applications. The novel approach of theory of characteristic mode analysis (TCMA) is introduced to provide physical insight of the designed structure and its characteristics behavior. Due to the suggested modifications in the geometry, the isolation among the patches is greatly increased. The overall miniaturized dimension of the MIMO antenna is 25 × 40 mm². The edge-edge spacing among the elements is 0.0233λ. The prototype antenna is fabricated and measured that shows good agreement compared with simulated results. The designed MIMO antenna without the presence of decoupling structure offers an isolation of 28 dB, gain of 3.6 dBi, and radiation efficiency of 69.7% at the resonant frequency. The proposed MIMO antenna covers a broad range of frequency band from 3.296 to 5.962 GHz with −10 dB impedance bandwidth of 2666 MHz and maintains a good isolation of greater than 50 dB for the entire operating band. The tested radiation efficiency and gain are 85.3% and 6.22 dBi at 3.5 GHz. Moreover, the diversity parameters of the neutralization line integrated MIMO antenna, that is, channel capacity loss (CCL) isolation, mean effective gain (MEG), total active reflection coefficient (TARC) diversity gain (DG), and envelope correlation coefficient (ECC), are analyzed and discussed in this article.     

一种小型化的高隔离度UWB-MIMO天线

提出了一种紧凑、高性能、形状新颖的具有高隔离度的超宽带多输入多输出(ultra-wideband multiple-input multiple-output, UWB-MIMO)天线.天线由两个圆形辐射元件组成,享有共同的类F形接地平面,尺寸为30 mm×18 mm.在天线的接地平面中引入类F形短截线,在MIMO天线元件之间产生高度隔离.所设计的UWB-MIMO天线具有极低耦合(S₂₁<-22 dB)、低包络相关系数(ECC<0.003)、高分集增益(DG>9.98 dB),适用于便携式通信设备.     

Design and Analysis of Multiband Fractal Antenna for MIMO/Diversity Applications

In this article a modified hybridized fractal geometry i.e., fractal antenna is proposed for Multiple Input Multiple Output (MIMO) applications. These geometries are based on Minkowski curves and Koch curves located around the boundaries of the microstrip patch of rectangular-shaped patch. The hybridized model for fractal geometry is designed and analyzed on an FR4 substrate having a thickness of 1.47 mm for the Industrial, Scientific, and Medical (ISM) frequency band. But due to the proposed fractal geometry, it resonates at three bands (2.45 GHz, 3.67 GHz, and 5.88 GHz) and it is covering the ISM band from 2.42 GHz to 2.48 GHz with a VSWR value is 1.48. Further, a 2?×?2 antenna for MIMO application is proposed by considering identical antenna elements placed in parallel on the same substrate. MIMO antenna resonates at three frequencies as same as single antenna elements and covering the same operating bands. The two elements of MIMO confguration are simulated for various sets of distance values, and optimized distance is obtained 18 mm at which a proposed antenna provides low mutual coupling value, low Envelope Correlation Coefficient (ECC), and high diversity and peak gain. The calculated values of ECC and diversity gain are 0.0002 and 10 dB, respectively which satisfy the criteria of MIMO application. The design has been experimentally validated and an appropriate similarity of experimental and simulated results is achieved.

     

Multi-Element Wideband Planar Antenna for Wireless Applications

A wideband, multi-standard MIMO antenna with hexagonal geometry and slot is proposed for DCS/PCS/LTE/UMTS applications while keeping the real time application at prime to provide high data rate, low latency, high capacity, non-line-of communication, and reliability with continuity. The designed prototype covers 1.64–2.50 GHz frequency band with percentage bandwidth of 41.55% and resonates at 2.1 GHz. The isolation of more than 10 dB is achieved in the 2:1 VSWR frequency band. The total bandwidth of the MIMO antenna is 860 MHz. The designed MIMO has peak gain of 5.4 dBi, ECC?<?0.06, radiation efficiency?>?88%, and total efficiency?>?71%. The TARC active bandwidth is 600 MHz with best excitation angles of 45°, 45° at ports. The hexagonal slot is used for the control of induced current for better isolation. The proposed MIMO antenna evaluates the SAR performance at resonant frequency for listening, holding, and watching positions, and is found under the required safety norms.

     

A dual-band multiple-input multiple-output microstrip antenna with metamaterial structure for LTE and WLAN applications

A method to enhance the gain of microstrip dual-band multiple-input multiple-output (MIMO) antenna using partially reflective surface (PRS) layer is introduced and investigated in this paper. The proposed antenna consists of two FR4 substrates. The lower substrate has two radiating patches with parasitic elements that are supplied independently and create the MIMO property of the antenna. The upper substrate which is known as superstrate is arrays of PRS unit cells. The PRS layer printed on either side of a dielectric substrate and causes the antenna gain to increase in both frequency bands. The proposed antenna is appropriate for LTE (2.4–3.1 GHz) and WLAN (5.1–5.8 GHz) applications. The measured values of S₁₁ and S₂₂ parameters of the antenna are less than −10 dB and its FBR and gain are 12.5 dB and 5dBi, respectively. The average half power beam-width (HPBW) is roughly 108^○.     

Octagonal DGS based dual polarised ring-shaped antenna for MIMO communications

In this article, a dual polarised Microstrip patch antenna is proposed for 2*2 MIMO communications. The proposed antenna is suitable for GSM/DCS-1800 and LTE-1900 bands as diversity and multiple-input multiple-output (MIMO) antenna. Different from conventional MIMO antennas, the radiating aperture is shared among the radiators, which greatly reduces the overall size of the MIMO antenna system. An isolation enhancement of 30 dB between the input ports is achieved by integrating cross-connected octagonal shaped Defected Ground Structure to the ground plane. Furthermore, the Multi-antenna system performance metrics such as Envelope Correlation Co-efficient, diversity gain and Mean Effective Gain, and Total Active Reflection Co-efficient are also computed. The Proposed antenna shows a gain of 3.63 dBi at 1950 MHz. The simulated and measured results demonstrate that the proposed antenna has good impedance matching, isolation and dual polarisation characteristics. From the performance metrics, the proposed antenna performs well in multipath environment.     

Isolation enhancement for dual‐band MIMO antenna system using multiple slots loading technique

In this paper, a novel multiple slot loading technique is studied in detail for the isolation enhancement of the dual‐band MIMO antenna system. The proposed MIMO antenna design consists of the microstrip patch loaded with T‐shaped slots parallel to the non‐radiating edge of the patch. The frequency tuning could be achieved by varying the length of the T‐shape slot arm. The proposed MIMO antenna system is optimised for operation in WLAN and WiMAX applications. The isolation enhancement is achieved by providing simple multiple slots loaded in the ground plane between radiating elements. The length of the slots is λ/4 . The system is fabricated and tested using a vector network analyser and anechoic chamber. The reduction in mutual coupling up to ?29.16 dB and ?24.09 dB for the 2.4 GHz and 3.4 GHz, respectively, is achieved. The bandwidths are 62.3 MHz (3.33–3.39 GHz) and 55.5 MHz (2.37–2.42 GHz), respectively. The total gain obtained in this case is 1.8 dBi at 2.4 GHz and 1.2 dBi at 3.4 GHz, respectively. The dimensions of the proposed designed antenna are 70 mm × 60 mm × 1.6 mm. The results were also verified through mutual coupling parameters like envelope correlation coefficient (ECC) and channel capacity loss (CCL) at the desired frequencies.