Super Compact UWB Monopole Antenna for Small IoT Devices

This article introduces a novel, ultrawideband (UWB) planar monopole antenna printed on Roger RT/5880 substrate in a compact size for small Internet of Things (IoT) applications. The total electrical dimensions of the proposed compact UWB antenna are 0.19 λ_o × 0.215 λ_o × 0.0196 λ_o with the overall physical sizes of 15 mm × 17 mm × 1.548 mm at the lower resonance frequency of 3.8 GHz. The planar monopole antenna is fed through the linearly tapered microstrip line on a partially structured ground plane to achieve optimum impedance matching for UWB operation. The proposed compact UWB antenna has an operation bandwidth of 9.53 GHz from 3.026 GHz up to 12.556 GHz at −10 dB return loss with a fractional bandwidth (FBW) of about 122%. The numerically computed and experimentally measured results agree well in between. A detailed time-domain analysis is additionally accomplished to verify the radiation efficiency of the proposed antenna design for the ultra-wideband signal propagation. The fabricated prototype of a compact UWB antenna exhibits an omnidirectional radiation pattern with the low peak measured gain required of 2.55 dBi at 10 GHz and promising radiation efficiency of 90%. The proposed compact planar antenna has technical potential to be utilized in UWB and IoT applications.     

Metamaterial-Based Compact Antenna with Defected Ground Structure for 5G and Beyond

In this paper, a unit cell of a single-negative metamaterial structure loaded with a meander line and defected ground structure (DGS) is investigated as the principle radiating element of an antenna. The unit cell antenna causes even or odd mode resonances similar to the unit cell structure depending on the orientation of the microstrip feed used to excite the unit cell. However, the orientation which gives low-frequency resonance is considered here. The unit cell antenna is then loaded with a meander line which is parallel to the split bearing side and connects the other two sides orthogonal to the split bearing side. This modified structure excites another mode of resonance at high frequency when a meander line defect is loaded on the metallic ground plane. Specific parameters of the meander line structure, the DGS shape, and the unit cell are optimized to place these two resonances at different frequencies with proper frequency intervals to enhance the bandwidth. Finally, the feed is placed in an offset position for better impedance matching without affecting the bandwidth The compact dimension of the antenna is 0.25 λL × 0.23 λL × 0.02 λL, where λL is the free space wavelength with respect to the center frequency of the impedance bandwidth. The proposed antenna is fabricated and measured. Experimental results reveal that the modified design gives monopole like radiation patterns which achieves a fractional operating bandwidth of 26.6%, from 3.26 to 4.26 GHz for |S11|<−10 dB and a pick gain of 1.26 dBi is realized. In addition, the simulated and measured cross-polarization levels are both less than −15 dB in the horizontal plane.     

Design of a Compact Monopole Antenna for UWB Applications

In this paper, a low cost, highly efficient and low profile monopole antenna for ultra-wideband (UWB) applications is presented. A new inverted triangular-shape structure possessing meander lines is designed to achieve a wideband response and high efficiency. To design the proposed structure, three steps are utilized to achieve an UWB response. The bandwidth of the proposed antenna is improved with changing meander lines parameters, miniaturization of the ground width and optimization of the feeding line. The measured and simulated frequency band ranges from 3.2 to 12 GHz, while the radiation patterns are measured at 4, 5.3, 6 and 8 GHz frequency bands. The overall volume of the proposed antenna is 26 × 25 × 1.6 mm3 ; whereas the FR4 material is used as a substrate with a relative permittivity and loss tangent of 4.3 and 0.025, correspondingly. The peak gain of 4 dB is achieved with a radiation efficiency of 80 to 98% for the entire wideband. Design modelling of proposed antenna is performed in ANSYS HFSS 13 software. A decent consistency between the simulated and measured results is accomplished which shows that the proposed antenna is a potential candidate for the UWB applications.     

V-Shaped Monopole Antenna with Chichena Itzia Inspired Defected Ground Structure for UWB Applications

Due to rapid growth in wireless communication technology, higher bandwidth requirement for advance telecommunication systems, capable of operating on two or higher bands with higher channel capacities and minimum distortion losses is desired. In this paper, a compact Ultra-Wideband (UWB) V-shaped monopole antenna is presented. UWB response is achieved by modifying the ground plane with Chichen Itzia inspired rectangular staircase shape. The proposed V-shaped is designed by incorporating a rectangle, and an inverted isosceles triangle using FR4 substrate. The size of the antenna is 25 mm×26 mm×1.6 mm. The proposed V-shaped monopole antenna produces bandwidth response of 3 GHz Industrial, Scientific, and Medical (ISM), Worldwide Interoperability for Microwave Access (WiMAX), (IEEE 802.11/HIPERLAN band, 5G sub 6 GHz) which with an additional square cut amplified the bandwidth response up to 8 GHz ranging from 3.1 GHz to 10.6 GHz attaining UWB defined by Federal Communications Commission (FCC) with a maximum gain of 3.83 dB. The antenna is designed in Ansys HFSS. Results for key performance parameters of the antenna are presented. The measured results are in good agreement with the simulated results. Due to flat gain, uniform group delay, omni directional radiation pattern characteristics and well-matched impedance, the proposed antenna is suitable for WiMAX, ISM and heterogeneous wireless systems.     

新型古币形超宽带分形印刷天线的设计

共面波导和分形结构结合应用,在展宽天线带宽方面具有独特优势.提出了一种新型古币形超宽带分形天线,采用共面波导馈电,并加载分形缝隙,天线的阻抗带宽大幅提高.给出了天线的表面电流、回波损耗、方向图和增益结果.对3阶分形天线进行了加工与测试,测试结果表明,天线带宽达到2.6～16 GHz,带宽比大于6:1.仿真结果与测试结果基本吻合,为超宽带小型化天线的设计提供了新的思路．     

A Novel Compact Highly Isolated UWB MIMO Antenna with WLAN Notch

This paper presents a compact Multiple Input Multiple Output (MIMO) antenna with WLAN band notch for Ultra-Wideband (UWB) applications. The antenna is designed on 0.8 mm thick low-cost FR-4 substrate having a compact size of 22 mm × 30 mm. The proposed antenna comprises of two monopole patches on the top layer of substrate while having a shared ground on its bottom layer. The mutual coupling between adjacent patches has been reduced by using a novel stub with shared ground structure. The stub consists of complementary rectangular slots that disturb the surface current direction and thus result in reducing mutual coupling between two ports. A slot is etched in the radiating patch for WLAN band notch. The slot is used to suppress frequencies ranging from 5.1 to 5.9 GHz. The results show that the proposed antenna has a very good impedance bandwidth of |S11| < −10 dB within the frequency band from 3.1–14 GHz. A low mutual coupling of less than −23 dB is achieved within the entire UWB band. Furthermore, the antenna has a peak gain of 5.8 dB, low ECC < 0.002 and high Diversity Gain (DG > 9.98).     

Reconfigurable Compact Wideband Circularly Polarised Dielectric Resonator Antenna for Wireless Applications

In this work, a novel compact wideband reconfigurable circularly polarised (CP) dielectric resonator antenna (DRA) is presented. The L-shaped Dielectric resonator antenna is excited by an inverted question mark shaped feed. This arrangement of feed-line helps to generate two orthogonal modes inside the DR, which makes the design circularly polarised. A thin micro-strip line placed on the defected ground plane not only helps to generate a wideband response but also assist in the positioning of the two diode switches. These switches located at the left and right of the micro-strip line helps in performing two switching operations. The novel compact design offers the reconfigurability between 2.9–3.8 GHz which can be used for different important wireless applications. For the switching operation I, the achieved impedance bandwidth is 24% while axial ratio bandwidth (ARBW) is 42%. For this switching state, the design has 100% CP performance. Similarly, the switching operation II achieves 60% impedance bandwidth and 58.88% ARBW with 76.36% CP performance. The proposed design has a maximum measured gain of 3.4 dBi and 93% radiation efficiency. The proposed design is novel in terms of compactness and performance parameters. The prototype is fabricated for the performance analysis which shows that the simulated and measured results are in close agreement.     

Compact coplanar waveguide-fed ultra-wideband monopole-like slot antenna

A simple and compact coplanar waveguide (CPW)-fed ultra-wideband (UWB) monopole-like slot antenna is presented. The proposed antenna comprises a monopole-like slot and a CPW fork-shaped feeding structure, which is etched onto an FR4 printed circuit board (PCB) with an overall size of 26 mm x 29 mm x 1.5 mm. The simulation and experiment show that the proposed antenna achieves good impedance matching, consistent gain, stable radiation patterns and consistent group delay over an operating bandwidth of 2.7?12.4 GHz (128.5%). Furthermore, through adding two more grounded open-circuited stubs, the proposed antenna design features band-notched characteristic in the band of 5?6 GHz while maintaining the desirable performance over lower/upper UWB bands of 3.1?4.85 GHz/6.2?9.7 GHz.     

Zero-Index Metamaterial Superstrates UWB Antenna for Microwave ImagingDetection

Metamaterials (MTM) can enhance the properties of microwaves and also exceed some limitations of devices used in technical practice. Note that the antenna is the element for realizing a microwave imaging (MWI) system since it is where signal transmission and absorption occur. Ultra-Wideband (UWB) antenna superstrates with MTM elements to ensure the signal transmitted from the antenna reaches the tumor and is absorbed by the same antenna. The lack of conventional head imaging techniques, for instance, Magnetic Resonance Imaging (MRI) and Computerized Tomography (CT)-scan, has been demonstrated in the paper focusing on the point of failure of these techniques for prompt diagnosis and portable systems. Furthermore, the importance of MWI has been addressed elaborately to portray its effectiveness and aptness for a primary tumor diagnosis. Other than that, MTM element designs have been discussed thoroughly based on their performances towards the contributions to the better image resolution of MWI with detailed reasonings. This paper proposes the novel design of a Zeroindex Split Ring Resonator (SRR) MTM element superstrate with a UWB antenna implemented in MWI systems for detecting tumor. The novel design of the MTM enables the realization of a high gain of a superstrate UWB antenna with the highest gain of 5.70 dB. Besides that, the MTM imitates the conduct of the zeroreflection phase on the resonance frequency, which does not exist. An antenna with an MTM unit is of a 7 × 4 and 10 × 5 Zero-index SRR MTM element that acts as a superstrate plane to the antenna. Apart from that, Rogers (RT5880) substrate material is employed to fabricate the designed MTM unit cell, with the following characteristics: 0.51 mm thickness, the loss tangent of 0.02, as well as the relative permittivity of 2.2, with Computer Simulation Technology (CST) performing the simulation and design. Both MTM unit cells of 7 × 4 and 10 × 5 attained 0° with respect to the reflection phase at the 2.70 GHz frequency band. The first design, MTM Antenna Design 1, consists of a 7 × 4 MTM unit cell that observed a rise of 5.70 dB with a return loss (S11) −20.007dB at 2.70 GHz frequency. The second design, MTM Antenna Design 2, consists of 10 × 5 MTM unit cells that recorded a gain of 5.66 dB, having the return loss (S11) −19.734 dB at 2.70 GHz frequency. Comparing these two MTM elements superstrates with the antenna, one can notice that the 7 × 4 MTM element shape has a low number of the unit cell with high gain and is a better choice than the 10 × 5 MTM element in realizing MTM element superstrates antenna for MWI.     

Wideband multilayered microstrip antennas fed by coplanar waveguide-loop with and without via combinations

Coplanar waveguide (CPW)-loop fed wideband multilayered microstrip antennas with and without via combinations are presented. The antenna consists of two dielectric substrates, CPW-loop on the ground plane layer, main patch on the middle layer and four asymmetric parasitic patches on the upper layer. The feed consists of a CPW, a loop on a ground plane and a via between main patch and feeding strip on the ground plane layer. Using via, the gain flatness over the impedance bandwidth and return loss are improved. The proposed antenna with four feeding structures is also studied. The 10 dB return loss bandwidths of the antenna with and without via are 34% (3.12? 4.41 GHz) and 33.7% (3.18 ?4.47 GHz), respectively. The measured gain is >5.0 dBi over the impedance bandwidth.     

Compact wideband Koch fractal printed slot antenna

A compact wideband printed slot antenna, suitable for wireless local area network (WLAN) and satisfying the worldwide interoperability for microwave access (WiMAX) applications, is proposed here. The antenna is microstrip-fed and its structure is based on Koch fractal geometry where the resonance frequency of a conventional triangular slot antenna is lowered by applying Koch iterations. The antenna size inclusive of the ground plane is compact and has a wide operating bandwidth. The proposed second iteration Koch slot antenna operates from 2.33 to 6.19 GHz covering the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands. The antenna exhibits omnidirectional radiation coverage with a gain better than 2.0 dBi in the entire operating band. Design equations for the proposed antenna are developed and their validity is confirmed on different substrates and for different slot sizes.     

Small modified monopole antenna for UWB application

In this paper, we present a novel modified printed monopole antenna (PMA) for ultra-wideband (UWB) applications. The proposed antenna consists of a truncated ground plane and radiating patch with two tapered steps, which provides wideband behaviour and relatively good matching. Moreover, the effects of a modified trapezoid-shaped slot inserted in the radiating patch, on the impedance matching and radiation behaviour is investigated. The antenna has a small area of 14 x 20 mm² and offers an impedance bandwidth as high as 100% at a centre frequency of 7.45 GHz for S₁₁ < -10 dB, which has a frequency bandwidth increment of 18% with respect to the previous similar antenna. Simulated and experimental results obtained for this antenna show that it exhibits good radiation behaviour within the UWB frequency range.     

小型化超宽带微带天线的设计

本文提出了一种结构简单的小型化超宽带微带天线,尺寸为28mm×30mm．天线采用渐变馈线对酒杯状贴片馈电,接地板采用缺陷地的结构．天线参数采用电磁仿真软件CST进行仿真和优化．测量结果显示该天线在S11小于-10dB时,相对带宽是170．1％（2．4GHz～30GHz）．实际制作了天线的样品并进行了测试,实测与仿真吻合良好．     

A Compact Flexible Circularly Polarized Implantable Antenna forBiotelemetry Applications

With the help of in-body antennas, the wireless communication among the implantable medical devices (IMDs) and exterior monitoring equipment, the telemetry system has brought us many benefits. Thus, a very thin-profile circularly polarized (CP) in-body antenna, functioning in ISM band at 2.45 GHz, is proposed. A tapered coplanar waveguide (CPW) method is used to excite the antenna. The radiator contains a pentagonal shape with five horizontal slits inside to obtain a circular polarization behavior. A bendable Roger Duroid RT5880 material (ε_r = 2.2, tanδ = 0.0009) with a typical 0.25 mm-thickness is used as a substrate. The proposed antenna has a total volume of 21 × 13 × 0.25 mm³. The antenna covers up a bandwidth of 2.38 to 2.53 GHz (150 MHz) in vacuum, while in skin tissue it covers 1.56 to 2.72 GHz (1.16 GHz) and in the muscle tissue covers 2.16 to 3.17 GHz (1.01 GHz). GHz). The flexion analysis in the x and y axes was also performed in simulation as the proposed antenna works with a wider bandwidth in the skin and muscle tissue. The simulation and the curved antenna measurements turned out to be in good agreement. The impedance bandwidth of −10 dB and the axis ratio bandwidth of 3 dB (AR) are measured on the skin and imitative gel of the pig at 27.78% and 35.5%, 13.5% and 4.9%, respectively, at a frequency of 2.45 GHz. The simulations revealed that the specific absorption rate (SAR) in the skin is 0.634 and 0.914 W/kg in muscle on 1g-tissue. The recommended SAR values are below the limits set by the federal communications commission (FCC). Finally, the proposed low-profile implantable antenna has achieved very compact size, flexibility, lower SAR values, high gain, higher impedance and axis ratio bandwidths in the skin and muscle tissues of the human body. This antenna is smaller in size and a good applicant for application in medical implants.     

Wideband circularly polarised slot antenna

A wideband circularly polarised slot antenna is presented. The slot antenna is fed by four microstrip line feeds orientated to have relative phases of 0deg, 90deg, 180deg and 270deg using a feed network comprising a pair of broadband 90deg hybrid. The proposed antenna delivers measured and simulated impedance bandwidths of 77.8% (1.02-2.32 GHz) and 89.1% (1.02-2.66 GHz), respectively, for standing wave ratio (SWR) < 2, measured and simulated axial-ratio bandwidths of 88.9% (1-2.6 GHz) and 81% (1.1-2.6 GHz), respectively, for axial ratio < 3 dB and measured and simulated gain bandwidths of 33% (1.5-2.1 GHz) and 27% (1.6-2.1 GHz), respectively, for gain >3 dB. A good agreement is observed between simulation and measurement.     

Linearly Polarized Millimeter Wave Reflectarray with Mutual Coupling Optimization

This work provides the design and analysis of a single layer, linearly polarized millimeter wave reflectarray antenna with mutual coupling optimization. Detailed analysis was carried out at 26 GHz design frequency using the simulations of the reflectarray unit cells as well as the periodic reflectarray antenna. The simulated results were verified by the scattering parameter and far-field measurements of the unit cell and periodic arrays, respectively. A close agreement between the simulated and measured results was observed in all the cases. Apart from the unit cells and reflectarray, the waveguide and horn antenna were also fabricated to be used in the measurements. The measured scattering parameter results of the proposed circular ring unit cells provided a maximum reflection loss of 2.8 dB with phase errors below 10°. On the other hand, the measured far-field results of the 20 × 20 reflectarray antenna provided a maximum gain of 26.45 dB with a maximum 3 dB beam width of 12° and 1 dB gain drop bandwidth of 13.1%. The performance demonstrated by the proposed reflectarray antenna makes it a potential candidate to be used in modern-day applications such as 5^th Generation (5G) and 6^th Generation (6G) communication systems.     

一种改善超宽带MIMO天线隔离性能的方法

多输入多输出(Multiple-InputMultiple-Output,MIMO)技术是现代通信技术的发展趋势,为移动通信的迅速更迭提供了极大支持.设计了一种二端口的超宽带MIMO天线,其-10 dB阻抗带宽从3.3 GHz扩展到9.1 GHz.通过在天线接地板上蚀刻一条宽缝隙,并在其中添加音叉型枝节,改善了超宽带M...     

Ultra-wideband quasi-circular monopole antennas with rectangular and trapezoidal grounds

Two planar quasi-circular monopole antennas with rectangular and trapezoidal grounds are presented. The impedance bandwidths of the two antennas, defined by measured return loss better than 10 dB, are from 1.3 to 18.4 GHz and from 1.1 to 13.5 GHz, respectively. Both numerical and experimental results show that the proposed antenna with trapezoidal ground has significantly improved radiation performance, compared with the one with rectangular ground. Parameters and design considerations of the trapezoidal ground are discussed in detail. These novel monopole antennas have very wide impedance bandwidth, compact size and low fabrication cost, which are suitable for various broadband applications.     

Artificial Magnetic Conductor as Planar Antenna for 5G Evolution

A 5G wireless system requests a high-performance compact antenna device. This research work aims to report the characterization and verification of the artificial magnetic conductor (AMC) metamaterial for a high-gain planar antenna. The configuration is formed by a double-side structure on an intrinsic dielectric slab. The 2-D periodic pattern as an impedance surface is mounted on the top surface, whereas at the bottom surface the ground plane with an inductive narrow aperture source is embedded. The characteristic of the resonant transmission is illustrated based on the electromagnetic virtual object of the AMC resonant structure to reveal the unique property of a magnetic material response. The characteristics of the AMC metamaterial and the planar antenna synthesis are investigated and verified by experiment using a low-cost FR4 dielectric material. The directional antenna gain is obviously enhanced by guiding a primary field radiation. The loss effect in a dielectric slab is essentially studied having an influence on antenna radiation. The verification shows a peak of the antenna gain around 9.7 dB at broadside which is improved by 6.2 dB in comparison with the primary aperture antenna without the AMC structure. The thin antenna profile of λ/37.5 is achieved at 10 GHz for 5G evolution. The emission property in an AMC structure herein contributes to the development of a low-profile and high-gain planar antenna for a compact wireless component.     

Compact dielectric resonator antenna for microwave breast cancer detection

A compact stair-shaped dielectric resonator antenna (DRA) is designed and fabricated for microwave breast cancer detection. A quarter-wavelength choke was incorporated to reduce the finite ground plane size. A more than 40% return loss of 10 dB centred at 6.5 GHz is achieved with a 50 Ω coaxial port. Parametric studies are carried out to provide practical insights into sensor design. The design is performed numerically and confirmed experimentally. A simple model for the tissue is considered and the interaction of the sensor with the tissue is investigated. Good matching is retained without adding any matching medium or lumped loads when the sensor is in contact with the tissue. A two-element sensor array is investigated numerically. A dipole antenna and a circular ultra-wideband dipole antenna are compared with the stair-shaped DRA with a choked ground plane. Preliminary results are obtained for the cases with different tumour locations. The DRA type of sensor reveals good potential for frequency-domain detection.