Dual Band Dual Polarization Directive Patch Antenna Using Rectangular Metallic Grids Metamaterial

In this letter, a kind of metamaterial superstrate based on rectangular metallic grids is presented to enhance the directivity of patch antenna at two frequency bands for two orthogonal polarizations. According to the periodic boundary condition, the influences of its important geometry parameters are investigated in detail by simulating its unit cell. It is found that the transmission peak frequency is intimately related to the size of rectangular metallic grid. Then, a dual band dual polarization patch antenna with metamaterial is studied and compared with conventional patch antenna. It is demonstrated that by introducing the proposed metamaterial superstrate, the gain of the patch antenna is improved by 9.5 dB at 14.1 GHz for x polarization and 12 dB at 15.4 GHz for y polarization, respectively.     

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.     

U-slot Loaded Half Disk Patch Antenna for Mobile Communications

Theoretical investigations of a U-slot loaded half disk patch antenna are presented using equivalent circuit concept. It is found that the antenna shows dual band characteristics with resonant frequency at 4.76 and 6.79 GHz. The dual nature of the antenna is realized by loading shorting pin with U-slot loaded patch. The lower and upper frequency bands are achieved as 443 and 287 MHz respectively. It is noted that the antenna shows frequency ratio of 1.4.     

Broadband circularly polarised crosspatch- loaded square slot antenna

A new design of a circularly polarised square slot antenna loaded with a cross patch is presented. A cross patch inclined diagonally with respect to the square slot is placed at the centre of the square slot. By choosing proper dimensions of the cross patch, two orthogonal resonant modes with a 90deg phase difference for circular polarisation can be excited and feed the square slot antenna using a 50 Omega CPW with a protruded signal strip. 10 dB return loss bandwidth of 846 MHz (39.6%) and 3 dB axial ratio bandwidth of 240 MHz (12.4%) for the proposed antenna are achieved. Gain variation within the CP bandwidth is observed to be less than 1 dB     

High mutual coupling reduction between microstrip patch antennas using novel structure

In this paper, a novel parasitic configuration to reduce the mutual coupling between two adjacent microstrip patch antennas is presented. It is shown that mutual coupling between the antenna elements can be reduced significantly by two simple slots structure on the ground plane and several shorted simple conducting strips between patch antennas. The structure has been constructed and tested. Both simulated and measured results are presented. The results are shown that more than 7 dB reduction within operational frequency bandwidth with the maximum 41 dB mutual coupling at center frequency can be achieved. The measurement results prove the high efficiency of this configuration in multi antenna systems.     

基于超材料完全吸收器的低RCS微带天线

为降低微带天线雷达散射截面(RCS),提出了一种基于超材料完全吸收器的微带天线。通过电磁场仿真软件设计了一种和微带天线工作频带匹配的圆环宽频带超材料吸收器,并将其加载在传统微带天线上制作成基于超材料完全吸收器的微带天线。实验结果表明,保持天线辐射性能不变的情况下,超材料吸收器可以有效减小天线RCS,其中,正面0°方向的RCS值最大缩减达到了-15.8 dB。     

K波段高增益超材料微带天线的拓扑优化设计

超材料微带天线的设计通常依赖经验,其中超材料基元的设计多以尺寸优化和形状优化为主。研究了常规超材料对微带天线增益性能的影响,发现其对增益性能的提升效果有限。提出了一种基于遗传算法的高增益超材料微带天线拓扑优化设计方法,对超材料基元采用整体设计的方法,以天线增益最大化为设计目标,以覆铜贴片方格子的有无为设计变量,建立了K波段(24 GHz)超材料微带天线的拓扑优化模型。进而基于遗传算法的求解策略,获得了一种新颖的超材料微带天线构型。仿真结果表明优化后的超材料微带天线侧向辐射得以抑制,其最大增益提升到10.5 dB,与普通微带天线相比性能提升了35%。同时通过改变覆铜贴片格子的布置规模对优化设计结果的收敛性进行分析,分析结果显示创新构型超材料微带天线设计结果是收敛的,且10*10方格子规模下的创新构型制备性价比最高。最后研究了超材料基元单独设计与整体设计的天线工作频率匹配对比,对比结果证实了超材料基元采用整体设计对于超材料微带天线拓扑优化是非常必要的。     

Dual band microstrip patch antenna array loaded with split ring resonators and via holes

Reduction in antenna size by using multi-band radiators play a vital role in the miniaturization of present world wireless handheld devices, as dual band behaviour of the antennas result in the integration of more than one communication standard in a single system and thus, saving the installation space required for separate antennas. In this context, this communication presents a shorted-pin dual band metamaterial inspired microstrip patch antenna array. Under the unloaded conditions, the traditional patch antenna array resonates at 5.8 GHz with gain of 9.8 dBi and bandwidth of 540 MHz. However, when each patch of this traditional antenna array is loaded with split ring resonator (SRR) and a metallic via hole is introduced in the patch, the same antenna array produces an additional resonant frequency in IEEE 802.11b/g/n 2.45 GHz Wi-Fi band with bandwidth and gain of 290 MHz and 5.6 dBi, respectively, while the initial resonant frequency (i.e. 5.8 GHz) gets shifted to IEEE 802.11ac 5 GHz Wi-Fi band, providing the gain and bandwidth of 11.4 dBi and 510 MHz, respectively. The proposed antenna array has been fabricated, and the measured results are presented to validate the proposed array. Moreover, the equivalent circuit of the proposed antenna array has been designed and analyzed to validate the simulated, measured and theoretical results. Attainment of dual band characteristics by incorporating the metamaterial with single band traditional patch antenna array makes this structure novel, as this has been achieved without any extra hardware cost, size and loss of structural planarity. Also, both the frequency bands of this proposed metamaterial inspired antenna array possess considerable gain and bandwidth.     

A Compact Plus Shaped Carpet Fractal Antenna with an I-Shaped DGS for C-band/X-band/UWB/WIBAN applications

This article presents the design and development of a compact broadband “+” shaped aperture coupled carpet fractal antenna with a defected ground structure (I shaped slot in the ground) for broadband/ultra wideband (UWB) and a multiband characteristics. The antenna has overall dimensions of 8.4 cm?×?5.5 cm?×?3.2 mm and is fed using aperture coupled feeding mechanism. It shows an impedance bandwidth (<?10 dB) of 4460 MHz from 6.93 to 11.39 GHz with fractional bandwidth of 0.48 at the center resonant frequency of 9.16 GHz. A multiband behavior is also exhibited by this antenna from 3.9–4.08 GHz, 4.8–5.06 GHz and 6.1–6.4 GHz with impedance bandwidths of 180 MHz, 260 MHz and 300 MHz respectively. It therefore supports the wireless applications of Wi-MAX (3.8–4.1 GHz), Wi-BAN/long distance radio telecommunication (4.8–5.06 GHz), wireless sensor networks (6.1–6.4 GHz), satellite (7.4–7.8 GHz) and UWB (6.9–11.03 GHz). The antenna is designed as a ‘+’ shaped patch with fractal rectangular slots cut out from it up to iterations of second order that allow the antenna to support multiband characteristics. The bandwidth at these bands is improved by using I shaped defected ground structure (DGS) and a parasitic feeding method i.e. aperture coupled feeding (Karur et al., in: ICMARS (IEEE), Jodhpur, India, pp. 266–270, 2014).The antenna has a compact structure with two layers of FR4 substrate, the ‘+’ shaped carpet fractal printed on the upper substrate layer and the lower substrate has a ground layer printed on its top and feed line on its bottom layer respectively. It shows a simulated peak gain of 4 dB at an operation frequency of 7.95 GHz. The antenna design and simulations are done using CST MWS V14. The Simulation results in terms of impedance bandwidth, smith chart, gain are presented in this article. To validate the impedance bandwidth results, the proposed carpet fractal antenna is experimentally tested using a vector network analyzer and the measured results are found to be closely matching with the simulated ones, allowing the antenna to be practically suitable for the afore mentioned wireless applications.

     

Mutual Coupling Reduction of MIMO Antenna Array Using Meta-FCRR

In order to reduce mutual coupling interference of between both adjacent antenna elements, a practical scheme for metamaterial is reported in this paper. The study shows that the permittivity and permeability of metamaterial based on fold complementary ring resonator (FCRR) can well be anastomosed in electromagnetic field. The antenna array using co-planar waveguide mode to expound the multiple input multiple output (MIMO) performance are further proposed. The results of simulated antenna array with FCRR indicate that the coupling of about 30.5 dB, 14 dB and 20.2 dB are reduced at resonance frequency (at 2.4 GHz, 6.15 GHz and 9.2 GHz). Meanwhile the experimental measure results can meet the simulation data. Additionally, the envelope correlation coefficient (ECC), diversity gain (DG), voltage standing wave ratio (VSWR) are better characteristics in contrasting to without FCRR, making the solution viable for MIMO antenna arrays.

     

λ/64‐spaced compact ESPAR antenna via analog RF switches for a single RF chain MIMO system

In this study, an electronically steerable parasitic array radiator (ESPAR) antenna via analog radio frequency (RF) switches for a single RF chain MIMO system is presented. The proposed antenna elements are spaced at λ/64, and the antenna size is miniaturized via a dielectric radome. The optimum reactance load value is calculated via the beamforming load search algorithm. A switch simplifies the design and implementation of the reactance loads and does not require additional complex antenna matching circuits. The measured impedance bandwidth of the proposed ESPAR antenna is 1,500 MHz (1.75 GHz–3.25 GHz). The proposed antenna exhibits a beam pattern that is reconfigurable at 2.48 GHz due to changes in the reactance value, and the measured peak antenna gain is 4.8 dBi. The reception performance is measured by using a 4  4 BPSK signal. The measured average SNR is 17 dB when using the proposed ESPAR antenna as a transmitter, and the average SNR is 16.7 dB when using a four‐conventional monopole antenna.     

一种基于超材料的谐波抑制天线罩

设计了一种基于超材料结构的前置谐波抑制单元天线罩,该天线罩采用多层互补型亚波长单元结构,在一个天线单元的有限尺寸范围内排列更多的周期单元,减小边缘效应的影响,天线罩总厚度小于5 mm,通过PMI泡沫与喇叭天线连接。采用激光刻蚀工艺制备了不同尺寸的两种试验件,并进行了超材料的传输系数测试以及带罩天线阵谐波抑制性能测试,结果表明,所设计的超材料谐波抑制天线罩具有带内0.3 dB 的插损,二次谐波20 dB和三次谐波30 dB的抑制能力。     

Analysis of Gunn integrated annular ring microstrip antenna

The analysis conducted on Gunn integrated annular ring microstrip antenna and evaluation of various parameters such as input impedance, voltage standing-wave radio voltage standing wave ratio (VSWR), return loss, bandwidth, radiation pattern, beamwidth, etc., as a function of bias voltage and threshold voltage reveals that the Gunn loaded patch offers wider tunability, better matching, enhanced radiated power as compared to the patch alone. Bandwidth of the Gunn loaded patch improves to 11.07% over the 7.9% bandwidth of the patch whereas the radiated power is enhanced by 3.7 dB as compared to the patch.     

Dual-band six-element switched parasitic array for smart antennacellular communications systems

Simulation results for a dual-band switched parasitic smart antenna array designed for cellular communications systems are presented. The array consists of six loaded monopole elements on an infinite ground plane and offers five switched directions equally spaced through 360°. At 900 and 1900 MHz, the 10 dB bandwidths are 15 and 13%, respectively. The antenna covers the azimuth plane with a maximum gain of 4 dBi and a minimum gain of 2 dBi. The front-to-back ratios of the radiation patterns are better than -15 dB. The design is robust in terms of manufacturing and environmental tolerances     

A miniaturized metamaterial slot antenna for wireless applications

A novel miniaturized five band metamaterial inspired slot antenna is reported. The proposed design consists of a ring monopole and metamaterial Rectangular Complementary Split Ring Resonator (RCSRR) as the radiating part, two L and one T–shaped slot as the ground plane, respectively. Miniaturization in the proposed design is accomplished by metamaterial RCSRR, and also, it helps the antenna to operate at 2.9 and 5.2 GHz frequency bands. The aforementioned miniaturization process leads to about 46.8% reduction in volume of the proposed design, as compared to the conventional antenna. The pass band characteristics of the metamaterial RCSRR through waveguide medium are discussed in detail. In order to enhance the operating abilities of the miniaturized antenna, slots are etched out in the ground plane, thereby making the miniaturized antenna further operate at 2.4, 5.6 and 8.8 GHz, respectively. The proposed design has an active patch area of only , with dB bandwidth of about 4.16% (2.35–2.45 GHz), 5.71% (2.63–2.76 GHz), 10.25% (4.44–4.92 GHz), 6.25% (5.42–5.77 GHz) and 2.39% (8.68–8.89 GHz) in simulation, and about 6.86% (2.25–2.41 GHz), 5.01% (2.55–2.7 GHz), 9.16% (4.58–5.02 GHz), 5.38% (5.79–6.11 GHz) and 5.42% (8.44–8.91 GHz) in measurement. The antenna has good impedance matching, acceptable gain and stable radiation characteristics across the operational bandwidths.     

基于人工电磁材料的微带贴片天线频带展宽

提出一种以人工电磁材料作为介质基板的矩形微带贴片天线。通过改变人工电磁材料各单元的几何尺寸来控制介质基板的参数变化,以构成非均匀介质基板,使得贴片辐射边的辐射性能提高,从而有效提高了带宽。对设计的非均匀介质微带天线使用HFSS软件仿真。结果表明,普通均匀介质微带天线电压驻波比VSWR≤2时带宽只有0.5GHz,相对带宽为6.7%,而以人工电磁材料为非均匀介质基板的微带天线VSWR≤2时带宽达到1.6GHz,相对带宽达到20.0%。     

A quad-polarization and frequency reconfigurable square ring slot loaded microstrip patch antenna for WLAN applications

In this paper, a novel polarization and frequency reconfigurable microstrip patch antenna which can switch between vertical and horizontal linear polarizations, left hand and right hand circular polarizations at two WLAN frequencies is presented. The orthogonal linear polarizations are achieved by a square microstrip patch antenna fed by two ports on adjacent sides. By introducing corner truncated perturbation on opposite corners of right diagonal of a square patch, orthogonal circular polarizations are achieved. By controlling the bias voltage of two PIN diodes loaded at perturbed corners, a single structure can achieve quad polarization states. Furthermore, by superimposing a square ring slot into the corner truncated square patch and incorporating four PIN diodes into the square ring slot, quad polarization are achieved at dual frequencies. Simulated and measured results indicate that the antenna can achieve quad polarization at two WLAN bands (5.15–5.35 GHz) and (5.75–5.85 GHz). The proposed antenna is simple, has low profile and can be scaled easily for other frequencies.     

A novel design of circularly polarised antenna based on metamaterial

This article presents a novel design of circularly polarised microstrip antenna based on a metamaterial reflection plane and a half-wave antenna. The metamaterial is composed of two pieces of substrates coated on one side with split ring resonators. Both the experimental and simulated results show that good circularly polarised radiation performances are obtained. The 10?dB return-loss impedance bandwidth and 3?dB axial ratio bandwidth of proposed antenna are 12% and 7%, respectively, and the gain of proposed antenna compared with the half-wave antenna is improved from 6?dB to 9?dB in the design frequency range.     

Slot-coupled microstrip antenna for broadband circular polarisation

A microstrip antenna with broadband circular polarisation (CP) is presented. The proposed microstrip antenna has a circular patch and is excited by a series microstrip-line-feed configuration through the coupling of a ring slot in the ground plane. The broadband operation is achieved by coupling two CP resonant elements, which are due to the circular patch and the ring slot, respectively. A typical prototype using foam material of thickness 5 mm as the antenna substrate is constructed. Measured results show the 3 dB-axial-ratio bandwidth centred at 2500 MHz is more than 10%.     

基于非均匀特异媒质的赋形天线设计

在PCB板表面蚀刻不同尺寸的微带单元结构,构建非均匀特异媒质层,并将其放置在天线辐射单元前方,利用非均匀特异媒质层对电磁波不同的反射系数,实现对天线辐射波束的赋形。设计了由不同尺寸正方形贴片组成的非均匀特异媒质层,并放置于工作频率为5.8 GHz的矩形贴片天线前方。仿真和测试表明:该非均匀特异媒质层能够在基本保持贴片天线工作频点和回波损耗曲线不变条件下,通过调整与贴片天线距离,实现辐射波束由笔形波束向宽角波束和马鞍形波束的赋形转换。为赋形天线设计提供了一种有效的新方法。