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.     

A reconfigurable wideband MIMO antenna combines RF energy harvesting

This article introduces a novel and groundbreaking approach combining multiple-input-multiple-output (MIMO) technology with radio frequency (RF) energy harvesting. The proposed antenna consists of two semi-circular monopole antenna components, optimized with dimensions of 89 × 51.02 × 1.6 mm³, that share a common ground plane to achieve MIMO characteristics. A series of split-ring resonators on the ground plane significantly enhances the isolation between the two radiating components. Band-notched features are performed in the 3.5 GHz WiMAX and 5.5 GHz WLAN bands through modified C-shaped slots in the radiating patch and two rectangular split-ring resonators serving as parasitic devices near the feed line. The reconfiguration of band-notching is made possible by controlling the modes of the embedded PIN diodes. The two antenna elements maintain mutual coupling below −18 dB from 1.5–13 GHz, achieving an impressive 158.62% impedance bandwidth. The antenna's efficiency and gain experience significant drop, indicating effective interference suppression at the center frequencies of the notch bands, and its performance in MIMO systems is assessed through parameters including envelope correlation coefficient, port isolation, radiation patterns, efficiency, gain, and diversity gain. The simulated properties of the designed antenna closely align with the measured outcomes, demonstrating its reliability and consistency. Moreover, the article evaluates the antenna's potential for RF energy harvesting, achieving a maximum harvested energy of 4.88 V. This proposed antenna can be used in multiple applications, like wideband, band-notching MIMO, and RF energy harvesting. This proposed antenna is an efficient, reconfigurable wideband MIMO antenna with novel RF energy harvesting capability.     

A Coalesced Kite Shaped Monopole Antenna for UWB Technology

A small and compact monopole antenna of dimensions 25?×?18?×?1.6 mm³ is presented for UWB communications. The proposed design consists of two kite shaped radiators in coalesced form and a tapered slotted ground plane for the UWB characteristics. The parametric study of the patch and the modified ground plane is made and the measured impedance bandwidth of 14.2 GHz (2.8–17 GHz) is achieved. The measured antenna gain varies from 2.28 to 5.0 dBi for the entire frequency band of application. Group delay, signal analysis and antenna isolation |S₂₁| are also studied at different orientations of the antenna and found to be quite satisfactory to meet the requirements for UWB applications. The co- and cross-polarization patterns are also calculated for E and H-planes, and compared with the measured results. Antenna simulation and optimization are performed using CST Microwave Studio and design is fabricated and measured for the validation of the results.

     

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.     

Compact CPW-Fed ultrawideband MIMO antenna using hexagonal ring monopole antenna elements

In this paper, a compact coplanar waveguide (CPW) fed ultra-wide band (UWB) multi input multi output (MIMO) antenna is proposed. The antenna consists of two antiparallel hexagonal ring monopole elements. Circular arcs shaped grounded stubs are used to enhance the isolation, both the arcs are connected through stub to make common ground. Tapering of the slots of CPW feed line at feed point, and grounded slots are introduced for impedance matching over UWB. The proposed antenna is fabricated and impedance bandwidth, isolation, radiation pattern, and gain are measured. Moreover, envelop correlation coefficient (ECC) results are given. Proposed antenna structure operates in the frequency range 3–12 GHz with a fractional bandwidth of 120% keeping isolation better than 15 dB. The antenna has a compact size of 45 × 25 mm².     

Printed Planar Monopole Antenna Design for Ultra-Wideband Communications

This paper presents an ultra wideband (UWB) planar printed monopole antenna fed by microstrip line. The antenna configuration contains a beveled ground plane. The beveled partial ground plane improves the impedance bandwidth. The measured frequency response demonstrates that the fabricated antenna exhibits an impedance bandwidth of 7.9 GHz over 3.1 to 11 GHz for VSWR < 2. The proposed antenna has ultra-wideband characteristics with omnidirectional radiation pattern and stable gain. Ultra-wideband performance of the proposed antenna is examined through the simulated surface current distributions. Measured results confirm that the antenna is suitable for UWB applications due to its compact size and high performance characteristics.     

A Pentagonal Shaped Microstrip Planar Antenna with Defected Ground Structure for Ultrawideband Applications

A new compact pentagonal microstrip patch antenna with slotted ground plane structure, developed for use in ultrawideband applications, is studied in this article. The proposed antenna is mainly constituted by a pentagonal shaped patch antenna, a defected ground plane structure, two stubs, and four slots to improve the bandwidth. The designed antenna has an overall dimension of 30?×?17.59?×?1.6 mm³, for WIMAX/WLAN/WiFi/HIPERLAN-2 /Bluetooth/LTE/5G applications with a very large bandwidth starting from 2.66 to 10.82 GHz (S₁₁?<???6 dB). A parametric study of the ground plane structure was carried out to find the final and the optimal UWB antenna, and to confirm that the antenna has good performance and broader bandwidth. The proposed antenna prototype has been fabricated. The measured results indicate that the antenna has a good impedance matching. The antenna has an electrically small dimension with a good gain, a notable efficiency, and a wide impedance bandwidth, which makes this antenna an excellent candidate for ultrawideband wireless communication, microwave imaging, radar applications, and the major part of the mobile phone frequencies as well.

     

Design of 3.1–12 GHz Printed Elliptical Disc Monopole Antenna with Half Circular Modified Ground Plane for UWB Application

This paper presents a new design of an elliptical disc monopole antenna for ultra wideband (UWB) applications. The antenna is fed by a 50 Ω microstrip line and printed on a dielectric FR4 substrate of permittivity ε _r  = 4.7 and height h = 1.6 mm. The optimization on the planar elliptical disc monopole has been presented to accomplish an ultra wide 10 dB return loss bandwidth. The design includes a half-modified circular ground plane with two short I-shaped sleeves in the middle to enhance the S-parameter characteristics across the whole UWB frequency band. Furthermore, compared to a simple rectangular shaped ground plane, the proposed design enhances the bandwidth and improves input return loss. The obtained results confirm that the proposed antenna achieves greater than 90 % radiation efficiency, better than 10 dB return loss, and 0.1 ns group delay in the frequency range of 3.1–12 GHz. The parameters, which affect the performance of the antenna with respect to frequency domain and time domain characteristics, are investigated also. In addition, the proposed antenna is fabricated and the simulation results are compared to the measurement results to prove the superiority of the antenna.     

Beam-Steerable Ultra-Wide-Band Miniaturized Elliptical Phased Array Antenna Using Inverted-L-Shaped Modified Inset Feed and Defected Ground Structure for 5G Smartphones Millimeter-Wave Applications

Multi Input Multi Output (MIMO) and phased array systems are considered a key technologies to realize the 5G communication systems. Therefore, the purpose of this research is the suggestion of a novel mm-wave Ultrawide Band (UWB) antenna design with compact and straightforward layout suitable for both MIMO and phased array systems. Hence, the designed antenna array has been studied separately as a MIMO antenna and as a phased array antenna to carefully assess the performance of each system. The single antenna design is an elliptical patch antenna where the design novelty lies in the combination of a modified inset-feed and defected ground structure to provide a large bandwidth without any compromise in the radiation performance, nor in antenna size and design simplicity. The Design process are performed using CST MWS software, where the Rogers RT/Duroid 5880 substrate is chosen to construct the antenna. A broadband characteristic of 8.7 GHz from 26 to 34.7 GHz with two resonant frequencies at 28 GHz and 33 GHz is obtained. A good radiation properties are achieved, where the gain is greater than 4.5 dB while the radiation efficiency exceeds 97% over the operating band. The MIMO and phased array antennas are made up of 12-elements of the single UWB-antenna arranged linearly along the width-edge of the smartphone mainboard. The MIMO antenna proves a high diversity performance in terms of Diversity Gain (DG), Envelope Correlation Coefficient (ECC), Total Active Reflection Coefficient (TARC), Channel Capacity Loss (CCL) and Mean Effective Gain (MEG), owing to the low mutual coupling less than ??20 dB, which is obtained using a separating slits between the elements. In addition, the suggested phased array provides a highly stable gain up to 15 dB over the entire bandwidth at broadside direction, besides the wide scanning range of?±?60° at 28 GHz and?±?40° at 33 GHz. Hence, the attained results assure that the suggested antenna could be appropriate for incorporation in 5G smartphones and other wireless devices and can be effectively used for both phased array and MIMO applications.

     

Bi-directional UWB MIMO Antenna for Superior Spatial Diversity,and/or Multiplexing MIMO Performance

In this paper, a two-element UWB MIMO antenna with bi-directional radiation pattern is designed for superior UWB MIMO performance. The designed antenna adopts asymmetric coplanar waveguide ground feeding. The proposed antenna ECC is lower than the ECC of its omni-directional peer antenna. Simulated and measured ECC is lower than 0.016 over the entire ultra-wide bandwidth (3.1–10.6 GHz). The isolation between elements of the designed antenna is 20–25 dB exceeding the average in recently published works. The designed antenna has a diversity gain of almost 10 dB and average multiplexing efficiency of 85% over the entire ultra-wide bandwidth. The antenna preserves radiation efficiency higher than 0.96 and gain 3 dB. The diversity performance of the proposed UWB MIMO antenna is proven through real rich-multipath indoor environment measurements. Stationarity of the elected channel is evaluated through 100 successive measurements separated by a 3-min period for 5 h long. The measured spatial correlation coefficients are much lower than 0.5 in different scenarios.     

Ultra Wide Band (UWB) Horseshoe Antenna for Future Cognitive Radio Applications

In this paper, an UWB micro-strip antenna design has been proposed which is suitable for future cognitive radio applications. The geometry of proposed antenna is composed of two semi-circles with their interior modified in order to achieve higher impedance bandwidth. The semi-etched ground provides further bandwidth enhancement. The proposed antenna is fabricated on an inexpensive dielectric substrate FR-4 with relative permittivity of 4.4 and thickness of 1.6 mm. The overall dimensions of UWB antenna are 60?×?60?×?1.6 mm and have a bandwidth of 5.7 GHz. The designed antenna covers the most commonly used wireless communication bands such as DCS-1800, ISM bands, GPS, Wi-MAX, WLAN, 3G, 4G, etc. The design process and the variations in antenna’s performance due to different parameters has been discussed. The design and simulation of the antenna are carried out in the Ansys Electronic Desktop HFSS. The measured results are in good agreement with simulated results and design theory which shows that the proposed antenna is good candidate for the UWB applications.

     

一种超宽带地板开槽单极子天线的设计

研制了一款超宽带印刷单极子天线。通过在接地板和单极子贴片底部开槽,展宽了天线频带,改善了天线带内特性,提高了天线增益。采用HFSS软件进行仿真,对天线模型参数进行优化,达到最佳设计效果。结果表明,改进后的天线-10 dB阻抗带宽为2.2~14.6 GHz,比原不开槽天线的-10 dB阻抗带宽增加了7.2 GHz。天线实现了小型化超宽带的同时,在整个超宽带匹配频段内,具有良好的驻波和方向图特性,在超宽带设备中有着很好的应用前景。     

平面三角形单极子天线展宽带宽研究

介绍了一种利用变形地板来展宽平面三角形单极子天线带宽的方法。通过在天线地板上刻蚀对称的变型L型缝隙,天线的阻抗带宽增加到2.5~10.8 GHz,带内驻波比(VSWR)＜2。对比没有刻蚀缝隙的天线,不仅工作频带得到展宽,而且保持了较好的辐射性能。测量和仿真结果表明,天线的工作频带能够覆盖整个超宽带(UWB)范围。     

采用阶梯形微带馈线的高隔离度超宽带MIMO天线

提出了一种小型二端口超宽带(UWB)多输入多输出(MIMO)天线。该天线由两个相同的矩形单极子和缺陷地结构(DGS)组成,通过改进阶梯形微带馈电线,在介质基板底层和顶层添加H 形枝节,并在辐射贴片上添加矩形条,提高了天线的带宽和隔离度。实验结果表明:该天线在1~20 GHz 工作频带内的隔离度大于21 dB,包络相关系数小于0.02。实测与仿真结果相符,表明该天线适用于UWB MIMO 系统,且该天线结构紧凑,尺寸仅为22 mm×29 mm×0.8 mm,可用于便携式通信设备。     

Design of a Planar Ultrawideband Antenna With a New Band-Notch Structure

A novel planar ultrawideband (UWB) antenna with band-notched function. The antenna consists of a radiation patch that has an arc-shaped edge and a partially modified ground plane. The antenna that makes it different from the traditional monopole antenna is the modification in the shape of ground plane, including two bevel slots on the upper edge and two semicircle slots on the bottom edge of the ground plane. These slots improve the input impedance bandwidth and the high frequency radiation performance. With this design, the return loss is lower than 10 dB in 3.1-10.6 GHz frequency range and the radiation pattern is highly similar to the monopole antenna. By embedding a pair of T-shaped stubs inside an elliptical slot cut in the radiation patch, a notch around 5.5 GHz WLAN band is obtained. The average gain is lower than -18 dBi in the stopband, while the patterns and the gains at frequencies other than in the stopband are similar to that of the antenna without the band-notched function.     

具有双带阻特性的超宽带缝隙天线

设计了一款微带馈电的超宽带缝隙天线,整体尺寸仅有30 mm×30 mm×1.6 mm,在3.08～11 GHz范围内驻波比小于2,可覆盖超宽带频段.为了实现对WiMAX和WLAN频段的陷波,分别在地板和馈线上蚀刻不同缝隙,仿真结果表明:在3.2～3.7 GHz,5 ～5.9 GHz驻波比大于2,增益显著下降,而在通带内仍然保持良好的全向辐射特性和稳定的增益.该天线结构简单、性能优良,能广泛应用于超宽带通信系统中.     

Printed elliptical monopole with shaped ground plane for pattern stability

A novel planar elliptical disc monopole antenna for universal mobile communication systems (UMTS) and ultra-wideband (UWB) dual network applications is presented. Printed on a FR4 dielectric substrate and excited by a microstrip transmission line, the antenna has a shaped ground plane featuring a wide impedance bandwidth with excellent omnidirectional pattern stability.     

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.

     

Elliptical slot loaded partially segmented circular monopole antenna for super wideband application

This article inspects partially segmented circular monopole with elliptical slot for super wideband applications. Two significant characteristics of proposed antenna design are: (i) partially segmented circular monopole, notch loaded elliptical ground plane along with tapered microstrip line provides super wide bandwidth; (ii) elliptical slot in between the partially segmented circular monopole reduces the lower operating frequency (1.07 GHz–0.96 GHz), which in turn enhance the bandwidth dimension ratio (BDR). For verifying the simulated outcomes, antenna prototype is practically constructed and measured. The proposed antenna design attains frequency range from 0.96 GHz to 10.9 GHz (VSWR < 2) with bandwidth ratio of 11.35:1 and percentage bandwidth of 167.22%. Bandwidth dimension ratio of proposed radiator is 6975.22. Frequency as well as time domain analysis of proposed radiator approves its applicability for super wideband wireless applications.     

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.