High-gain composite microstrip patch antenna with the near-zero-refractive-index metamaterial

A high-gain rectangular microstrip patch antenna which is covered by a single layer metamaterial (MTM) superstrate with the near zero refractive index is proposed. The refraction of the metamaterial at frequency 3.51 GHz–3.57 GHz is very close to zero. The metamaterial with the near zero refractive index is placed 42 mm above an ordinary rectangular microstrip patch antenna. The effectively zero refractive index behavior of metamaterial superstrate can gather the wave emitted from the microstrip patch antenna and collimate it toward the normal direction of the antenna. The finite element method (FEM) and the finite difference time domain (FDTD) method are used to study the characteristics of this antenna. The results of the two methods indicate that the realized gain of the proposed antenna is increased by more than 6 dB, and the antenna has a flatness high gain in the predicted frequency band, where the proposed MTM is designed to have a near zero index of refraction. Therefore, the high-gain antenna is effectively enhanced based on the near-zero-refractive-index metamaterial.     

一种基于共享孔径Fabry-Perot谐振腔结构的宽带高增益磁电偶极子微带天线

设计了一种工作于X波段的基于共享孔径Fabry-Perot(F-P)谐振腔结构的宽带高增益磁电偶极子微带天线,并设计了三种不同尺寸的双层频率选择表面(FSS)单元,通过共享孔径布阵组成了超材料覆层.利用三种FSS单元的相位补偿特性,有效拓展了覆层天线的增益带宽.实测和仿真结果均表明,加载超材料覆层后,磁电偶极子天线在7.8—12.3 GHz内S_(11)-10 d B,相对带宽达到44.7%,覆盖整个X波段.天线增益在7.9—12.1 GHz内均有明显的提高,最大提高了7 d B.相较于传统的F-P谐振腔结构覆层天线,设计的基于共享孔径的F-P谐振型超材料覆层天线能够明显拓展天线增益带宽,在新型宽带高增益天线设计方面具有广阔的应用前景.     

Simulation-based analysis of performance parameters of microstrip antennas with criss-cross metamaterial-based artificial substrate

In this paper, we present the design of a metamaterial-based microstrip patch antenna, optimized for bandwidth and multiple frequency operations. A criss-cross structure has been proposed, this shape has been inspired from the famous Jerusalem cross. The theory and design formulas to calculate various parameters of the proposed antenna have been presented. Design starts with the analysis of the proposed unit cell structure, and validating the response using software– HFSS Version 13, to obtain negative response of ε and μ– metamaterial. Following this, a metamaterial-based-microstrip-patch-antenna is designed. A detailed comparative study is conducted exploring the response of the designed patch made of metamaterial and that of the conventional patch. Finally, antenna parameters such as gain, bandwidth, radiation pattern, and multiple frequency responses are investigated and optimised for the same and present in table and response graphs. It is also observed that the physical dimension of the metamaterial-based patch antenna is smaller compared to its conventional counterpart operating at the same fundamental frequency. The challenging part was to develop metamaterial based on some signature structures and techniques that would offer advantage in terms of BW and multiple frequency operation, which is demonstrated in this paper. The unique shape proposed in this paper gives improvement in bandwidth without reducing the gain of the antenna.     

Antenna gain enhancement by using metamaterial radome at THz band with reconfigurable characteristics based on graphene load

The reconfigurable concept of a graphene loaded patch antenna with increasing gain is proposed in this paper. We have developed the patch antenna with inset feed for THz band application for which graphene load is used to obtain the reconfigurable characteristic. It has been shown that by increasing the graphene chemical potential, the antenna resonant frequency shifted and the gain increased drastically up to 4 dBi. Additionally, we have shown that antenna efficiency is improved up to 78% which shows more than 100% of enhancement in comparison to basic antenna by increasing the graphene chemical potential. Finally, considering the antenna gain improvement, we have implemented the metamaterial layer over the antenna. In this case, the gain is increased more than 5–6 dBi. In addition, when we put the metamaterial layer over the antenna, the graphene layer shows more linear characteristics. By using parametric studies, we have defined the best point for metamaterial layer around 0.58λ. The final antenna gain is more than 11 dBi, which is useful for THz communication and THz medical imaging systems.     

S波段超材料完全吸收基板微带天线

设计了基于树枝状结构单元模型的完全吸波超材料,并将此树枝状结构完全吸波超材料作为微带天线的基板,制备了S波段超材料完全吸收基板微带天线,模拟和实验结果表明,窄带和宽带完全吸波超材料都可提高微带天线的定向性和增益,性能得到了明显改善.经过优化设计S波段超材料完全吸收基板微带天线的增益相比普通微带天线提高了1.8 dB,相当于有效辐射功率提高了51%.表明将完全吸波超材料作为天线的基板,可以明显改善天线性能. 关键词： 树枝状结构 微带天线 完全吸波材料 增益     

一种新型的树枝状负磁导率材料微带天线

基于树枝状金属结构单元模型的电磁特性,设计了一种双面刻有树枝状金属结构单元阵列的负磁导率介质材料,并将这种介质材料作为微带天线的基板,制备了中心工作频率为2.64GHz的树枝状负磁导率材料微带天线.仿真和测量结果都表明：相比普通微带天线,树枝状负磁导率材料微带天线的性能得到了明显改善,定向性得到了提高,E面和H面的3dB角分别收缩了18°和13°,增益提高了2.19dB,相当于有效辐射功率提高了65%.说明利用负磁导率材料作为微带天线的基板,可以明显改善微带天线的性能. 关键词： 树枝状结构 微带天线 负磁导率 增益     

Composite metamaterial enabled excellent performance of microstrip antenna array

This paper reports that the split ring resonators and complementary split ring resonators are compounded to construct a novel compact composite metamaterial.The composite metamaterial exhibits a unique property of blocking electromagnetic wave propagating in two directions near the resonant frequency.An example of two-element microstrip antenna array demonstrates that the developed metamaterial enables array performance that is an improvement in comparison with the traditional one,including mutual coupling suppression of 9.07 dB,remarkable side lobe suppression and gain improvement of 2.14 dB.The mechanism of performance enhancement is analysed based on the electric field and Poynting vector distributions in array.The present work not only is a meaningful exploration of new type composite metamaterial design,but also opens up possibilities for extensive metamaterial applications to antenna engineer.     

Meandered multiband metamaterial square microstrip patch antenna design

Magnetic properties can be imparted to a naturally nonmagnetic material by metallic inclusions. A multiband meandered square microstrip patch antenna loaded with such a metamaterial is reported. Metamaterials exhibit qualitatively new electromagnetic response functions that cannot be found in nature. The inclusion of these structures allows simultaneous operation over several frequencies. The antenna was designed to function in multiple bands in the frequency range 0.6–2.2?GHz. The antenna has eight working frequency bands and its centre frequencies are 670?MHz, 1185 MHz, 1293?MHz, 1747?MHz, 1909?MHz, 1999?MHz, 2063?MHz and 2134?MHz. The metamaterial also enhances the gain of the antenna, which is applicable for several wireless applications. Design results were obtained by a high frequency structure simulator which is used for simulating microwave passive components.     

近零介电常数材料用于天线口面加载研究

近零介电常数材料常用于口面加载以修正天线波前相位,提高口径效率。在对以往金属线阵周期结构研究基础上,提出了介质镀膜板周期结构的近零介电常数材料,并基于NRW本构参数法计算得到了该材料的等效介电常数,依据口面相位差平方和最小原则研制了中空形式的介质镀膜中空板加载结构。实验结果表明,X波段角锥天线加载后其主轴增益最大提高了1.8 dB,口径效率从原有0.4提高至0.6以上,相对工作带宽大于10%。     

Multiband metamaterial truncated square microstrip-based radiating structure design

We have reported multiband meandered truncated square microstrip patch antenna loaded with metamaterial in this paper. The patch is meandered at edges and truncated at corners. Metamaterials are composite materials that provide some unique characteristics, which are not available in nature. The inclusion of these structures allows simultaneous operation over several frequencies. The antenna is designed to function in multiple bands in the frequency range of 0.5–2.0 GHz. The antenna has five working frequency bands and its center frequencies are 660, 950, 1330, 1580, and 1750 MHz for design 1. We have obtained design 2 by changing the slit size and the design has five working frequency bands. Design results are obtained by a high frequency structure simulator which is used for simulating microwave passive components.     

Design and implementation of dual-band antennas based on a complementary split ring resonators

A simple dual-band antenna design and implementation method is proposed in this work, based on the equivalent media properties inspired by resonant metamaterial elements. The equivalent circuit model of dual-band patch antennas based on a complementary split ring resonator (CSRR) is presented and validated. The dual-band patch antenna is designed etching a CSRR in the patch of a conventional rectangular microstrip patch antenna. The first resonance is governed by the quasi-static resonance of the CSRR while the second resonance is originated by the rectangular patch. The fact of etching a CSRR on a rectangular patch antenna also produces a miniaturization of a conventional patch antenna. The equivalent circuit model proposed in this letter is sound in order to understand the functionality of dual-band patch antennas based on a CSRR. Good agreement between simulation, equivalent circuit model and experimental results is shown and discussed. These results lead the equivalent circuit model to become a simple and straightforward tool for the design of this type of multiband antennas, of low cost and versatile operation for a broad range of wireless communication systems.     

一种辐射零点可控的紧凑型滤波贴片天线

提出了一种辐射零点可控的紧凑型滤波贴片天线。该滤波天线以基本的微带贴片天线为原型,主要由一个简单的金属辐射贴片和两个对称的分割形槽组成。两个分割形槽蚀刻在金属贴片上,使得高/低频段分别产生两个宽边辐射零点,从而引入滤波选频功能。该结构未引入额外滤波电路和其他寄生单元,节省了空间尺寸,结构更加紧凑;两个辐射零点独立可控,提高了设计的灵活度。且在实现滤波选频功能的同时,对天线增益的影响很小。利用HFSS仿真软件优化滤波天线结构,制作了一个实物模型并进行了测试。测试结果与仿真结果基本一致。测试结果表明,提出的滤波天线工作在2.40 GHz,两个独立可控的辐射零点分别位于1.96 GHz和2.66 GHz,平均实际增益约为7.0 dBi,带外抑制水平超过39 dB。     

基于缺陷接地结构的太赫兹双频微带天线

提出了一种工作在太赫兹频段的双频微带天线。在普通矩形微带天线的基础上,在辐射贴片上加载45°和135°的矩形贴片增大辐射面积,增大高频谐振点处阻抗带宽。通过引入缺陷接地结构使得天线在接地板处的电流路径改变,并与辐射贴片相互耦合,从而实现双频特性。为提高天线增益,在辐射贴片边缘加载若干寄生矩形贴片,并增加了寄生贴片处的基板厚度。该款天线可以同时在520 GHz(508~532 GHz)和680 GHz(581~766 GHz)的频段下工作,其中高频段的相对带宽达到了27.5%,最大增益达到了3.54 dB和4.11 dB。该双频天线结构相对简单,各项性能指标稳定,对于工作在太赫兹频段上的通信系统和无线传输系统具有一定的应用价值。     

Complementary electric-LC resonator antenna for WLAN applications

In this paper, a metamaterial antenna based on complementary electric-LC (CELC) resonator is proposed. The antenna consists of slot-loaded ELC on the ground plane as the main antennas radiating element and excited by a microstrip line. The CELC resonator is characterized by single-negative magnetic moment excited by coupling between the microstrip transmission line and slot-loaded CELC. The peak realized gain and efficiency of 2.63 dB and 86 % are obtained, respectively, at resonance frequency. Simulation and measurement results are presented to validate the design. The antenna is suitable for WLAN applications (2.39–2.48 GHz).     

一种高增益低雷达散射截面的新型圆极化微带天线设计

设计了一种基于人工电磁材料覆层的高增益低雷达散射截面(radar cross section, RCS)圆极化微带天线. 人工电磁材料覆层是由介质板及其两侧的人工周期表面构成, 上表面是加载集总电阻的方环贴片, 具有宽带吸波特性; 下表面是开条带缝和圆环缝的金属贴片, 具有部分反射特性. 将其加载到圆极化微带天线上方, 通过覆层上表面的电阻可吸收入射的雷达波, 结合下表面与接地板构成Fabry-Perot谐振腔的多次反射, 可实现圆极化微带天线辐射和散射性能的同时改善. 实测结果表明: 加载人工电磁材料覆层后, 天线的相对轴比带宽由5.9%扩展为7.1%; 天线增益在整个工作频带内都得到了提升, 最大提高了6.61 dB; 天线RCS在宽频带宽角域内实现了明显的减缩, 在天线工作频带内也实现了3 dB以上减缩. 实测结果与仿真结果符合较好.     

Silver nanoparticles on conducting electrode: a simple two-step process for realizing plasmonic solar cell design

In this paper we address the introduction of antenna’s radiation pattern agility using an agile metamaterial. We design an agile metamaterial having two different behaviors which can be controlled by an external command. This agile metamaterial is used to design an agile lens which comprises two grids each composed of two regions: the first one constitutes a focusing zone (FZ) and the second one the lens body. The focusing zone parameters—refraction index, size, shape and position in the grid—can be modified using an external switching system (OFF or ON stat); by modifying the FZ parameters one can control the patch antenna’s radiation-pattern main-lobe beamwidth and direction (pointing angle) in E- and H-planes.     

Analysis and design of optically transparent antenna on photonic band gap structures

An optically transparent microstrip patch antenna is designed on photonic bandgap structures and its radiation characteristics are computed and analyzed in the visible spectrum region. The proposed antenna consists of indium tin oxide, a transparent conducting material used both as a radiating patch and a ground plane separated by the 5 μm thin glass substrate. The introduction of periodic cylindrical air cavity structures in the glass substrate leads to the formation of photonic band gap. The patch thickness is carefully selected based on the analysis of the optical transmission coefficient with respect to patch thickness. The effective dielectric constant of the photonic band gap loaded glass substrate is computed using the effective medium approach. The refractive index of the proposed antenna is presented and discussed. The radiation efficiency of the antenna is shown to improve significantly due to insertion of proposed photonic band gap structures. The proposed design has yielded a bandwidth of 2–2.3 THz for a return loss (S₁₁) of less than −15dB and achieved a peak gain of 4.97dB at 2.27 THz.     

Analysis of graphene based optically transparent patch antenna for terahertz communications

With and without multi walled carbon nanotube (MWCNT) loaded graphene based optically transparent patch antennas are designed to resonate at 6 THz. Their radiation characteristics are analyzed in 5.66–6.43 THz band. The optically transparent graphene is deployed as the patch and ground plane of the antennas, which are separated by a 2.5 μm thick flexible polyimide substrate. By shorting the microstrip line and ground plane of the antenna with a MWCNT via, the return loss of the antenna is improved. The peak gain of 3.3dB at 6.2 THz and a gain greater than 3dB in 5.66–6.43 THz band is obtained for antenna loaded without MWCNT. Both the antennas achieved a −10dB impedance bandwidth of 12.83%. Gain, directivity and radiation efficiency of the proposed antennas are compared with conventional transparent patch antennas and graphene based non-transparent antennas. The antenna structures are simulated by using finite element method based electromagnetic simulator-Ansys HFSS.     

Design considerations for rectangular microstrip patch antenna on electromagnetic crystal substrate at terahertz frequency

The effects of 2-D electromagnetic crystal substrate on the performance of a rectangular microstrip patch antennas at THz frequencies is simulated. Electromagnetic crystal substrate is used to obtain extremely broad-bandwidth with multi-frequency band operation of the proposed microstrip antennas. Multi-frequency band microstrip patch antennas are used in modern communication systems in order to enhance their capacity through frequency reuse. The simulated 10 dB impedance bandwidth of the rectangular patch microstrip antenna is 34.3% at THz frequency (0.6–0.95 THz). The radiation efficiency, gain and directivity of the proposed antenna are presented at different THz frequencies. The simulation has been performed using CST Microwave Studio, which is a commercially available electromagnetic simulator based on finite integral technique.