电磁带隙微带天线馈源阵设计

 针对阵列天线在大反射面馈电中的应用,设计一种基于电磁带隙（EBG）结构的馈源阵列。在深入研究EBG结构带隙特性的基础上,制作一个基于EBG结构的六边形7元微带天线阵,并对其性能进行了实测和分析。结果表明：EBG结构可以有效抑制天线阵元之间的互耦,改善天线匹配及圆极化特性;基于EBG结构的六边形馈源阵列较无EBG结构性能有较大提高,适用作反射面天线的焦平面馈电阵。     

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.     

宽带高增益双层硅基MEMS微带天线阵列

针对传统微带天线带宽窄和增益低等问题,设计了一种易与射频（RF）前端集成的硅基微带天线。该天线设计结合MEMS工艺,将高阻硅和低阻硅通过键合工艺形成双层硅基底,来改善微带天线介质基板的等效介电常数,有效增大了天线的带宽。同时通过在地面引入缺陷地结构（DGS）,有效的抑制谐波的产生。在此基础上设计了中心频率为10 Hz,22天线辐射阵列。仿真结果表明,天线相对阻抗带宽达到15.9%,增益超过10.9 dB,比传统微带天线有明显提升,同时满足引信中天线抗干扰的要求。     

Microstrip Array with PBG Substrate

The phased array formed by microstrip antennas is analyzed using the full wave Transverse Transmission Line (TTL) method. For the microstrip patch resonator a set of equations that represents the electromagnetic fields in the x and z directions as function of the fields in the y direction are obtained applying the TTL method. The structure PBG (Photonic Band Gap) is analyzed using the homogenization theory, the objective is obtain the equivalent permittivity of structure. Numerical results of the radiation pattern for some phase excitation in a phased array are shown.     

Performance analysis and comparison of MWCNT loaded ITO and TIO based optically transparent patch antennas for terahertz communications

Multiwalled carbon nanotube (MWCNT) loaded transparent conducting oxide materials (TCOMs) based optically transparent antennas are designed to resonate at 750 GHz. TCOMs such as indium-doped tin oxide (ITO) and titanium-doped tin oxide (TIO) are used for designing the transparent terahertz patch antennas. Shorting pin technique is used to improve the impedance performances of the transparent antennas. The MWCNT is used for shorting the microstrip line with the ground plane of the antenna. By varying the position of short with respect to the antenna patch, the resonant frequency of the antennas are optimized to resonate at 750 GHz. The impedance and radiation performances of the MWCNT loaded transparent antennas are compared. A broad impedance bandwidth (−10 dB) is achieved for both the proposed antennas. The MWCNT shorting pin effect on radiation performances of the transparent antennas are discussed in detail. The antennas are simulated using finite element method (FEM) based electromagnetic solver, Ansys-HFSS.     

Rectangular patch antennas over electromagnetic band gap structures

In this paper, I propose a new design of a defected structure (DS) for use as an electromagnetic band gap (EBG) configuration to enhance the performance of low profile microstrip antennas. The proposed defected structure embodies a honeycomb lattice of cylindrical air holes. The proposed DS is applied to three different configurations using a dielectric substrate (dielectric constant 6 and thickness 1.5 mm); namely: a dielectric substrate backed by a defected ground plane, a defected dielectric substrate backed by a normal substrate and a defected dielectric substrate backed by a defected ground plane. The simulated values of the transmission coefficient S ₂₁ for the last one show two well-defined stop bands around 8.5 and 9.5 GHz, respectively. The first band has been used to reduce mutual coupling in a microstrip array. On the other hand, the stop band defined around 9.5 GHz has been applied to enhance the characteristics of a rectangular patch antenna and improve the operational 10-dB bandwidth.     

微带阵列天线的时域散射特性

本文用时域有限差分方法(FDTD)研究了微带阵列天线的时域散射场,分析了入射脉冲极化方向不同以及入射方向不同时的散射场的分布情况;讨论了时域散射场的时域波形以及频谱与微带阵列天线结构的关系;用散射场分离算法讨论了地板对于微带贴片阵列散射场的影响.研究发现,有限大地板的微带阵列天线的散射场主要是由地板的边沿电流产生的,同时微带贴片阵列的谐振频率与入射脉冲的极化方向有关,因此不同的极化方向对应于不同的散射频谱. 关键词： 时域散射 微带天线 FDTD     

A Plane-Wave Beam-Steering Lens Design Using Microstrip Switched-Line Phase Shifters

A compact beam-steering lens design appropriate for millimeter-wave and submillimeter-wave applications is experimentally verified with an X-band test model. The lens achieves coupling to plane-wave beams through arrays of patch antennas placed on its two outer surfaces. The isolation between input and output antennas is accomplished by inserting a metal ground plane in the middle of the lens. The two closest patch antennas on the front and the backside are connected together with microstrip circuits that include switched-line phased shifters and interconnecting vias through the lens substrate. Three different X-band 100-element plane-wave microstrip lenses that use passive delay lines instead of actual phase-shifters were fabricated to successfully demonstrate the beam-steering angles of 20 and 40 degrees. From a separate waveguide measurement on the unit-cell element only, the insertion loss of the lens was estimated to be approximately 3.5 dB with bandwidth of 2% at 10 GHz.     

Decoupling technique of patch antenna arrays with shared substrate by suppressing near-field magnetic coupling using magnetic metamaterials

In this paper,we propose the decoupling technique of patch antenna array by suppressing near-field magnetic coupling(NFMC) using magnetic metamaterials.To this end,a highly-integrated magnetic metamaterials,the substrate-integrated split-ring resonator(SI-SRR),is firstly proposed to achieve negative permeability at the antenna operating frequency.By integrating SI-SRR in between two closely spaced antennas,magnetic fields are blocked in the shared substrate due to negative permeability of SI-SRR,reducing NFMC between the two antennas.To verify the technique,a prototype was fabricated and measured.The measured results demonstrated that the isolation can be enhanced by more than 17 dB even when the gap between the two patch antennas is only about 0.067 A.Due to high integration,this technique provides an effective alternative to high-isolation antenna array.     

Planar superstrate for dual-frequency RHCP-LHCP array

Patch antennas are low profile, lightweight and most suitable for aerospace and mobile applications. In recent years Fabry–Pérot cavities and meta-surfaces have been used as superstrates to improve the radiation performance of planar antennas (Saenz et al., IEEE Trans. Antennas Propag. 56(4), 2008; Iriarte et al., IEEE Trans. Antennas Propag. 57(1), 2009) such as directivity, mutual coupling on array configuration and bandwidth. These structures usually work for a single polarization and frequency band, while an increasing number of applications require multifrequency operation. In this paper a Fabry–Pérot cavity that works with dual-polarized and dual-frequency patch antennas (rectangular patch excited orthogonally) is proposed in order to design high-directivity dual-frequency RHCP-LHCP Arrays.     

Optical microstrip patch antennas design and analysis

This paper has presented transparent conductor oxide materials (TCOMs) based microstrip patch antennas with glass substrate and copper ground plane, which have been deeply analyzed in the visible spectrum region in comparison with the practical patch antenna model of indium tin oxide patch with glass substrate and different TCOMs based ground plane. As well as the study have investigated the effect of transparent oxide materials on patch antenna design instead of perfect conductor materials such as copper that has low cost and weight. The tradeoff between optical transparency and electrical conductivity will be evaluated for a range of visible regions. Microstrip transmission line feed method is used to predict the skin effects on a patch antenna and their impact on antenna efficiency, resonance frequency and optical transmission are also described. This study have discussed assessment of these tradeoffs and effect of TCOMs parameters on antenna design.     

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.     

级联电磁带隙结构对双频微带天线互耦的影响

一种均匀面片尺寸的图钉型电磁带隙结构只能实现一个表面波带隙,而将不同参数的图钉型电磁带隙结构级联可以实现多个或宽带的表面波带隙。利用不同金属面片尺寸的图钉型电磁带隙结构级联的方法实现双带的表面波带隙。设计两种均匀的电磁带隙结构,使其带隙范围分别覆盖天线的两个工作频带,然后将这两种结构级联起来,加载于两个缝隙天线单元之间。仿真分析和实验结果表明,级联型的电磁带隙结构可以有效抑制表面波,在两个频率带内同时减小互耦。     

Approaches to the creation of an active electrically small superconductive antenna

The physical principles of designing active electrically small superconductive antennas are investigated. These antennas are based on an array of superconducting quantum interference cells characterized by a high linearity of magnetic-signal conversion into voltage. The results of experimental investigation into an active antenna prototype containing 80 cells connected in series and occupying an area of 3.3 × 3.3 m are presented. The proposed integrated circuit is fabricated via the standard niobium technique of the formation of Josephson-junction elements with a critical current density of 4.5 kA/cm².     

Design of a Compact Millimeter-Wave Microstrip Antenna with Wide Bandwidth and Broad Beamwidth

Design of a novel compact millimeter-wave microstrip antenna with wide bandwidth and broad beamwidth is presented. In the structure, multiple layers and a parasitic element as well as a coupling aperture are used to achieve wideband, while a conducting cylinder and the coupling aperture are used to obtain broad beamwidth. Finally, phased array with eight present elements has been designed as an example. Compared to traditional microstrip antennas and arrays, present antenna and array are of smaller dimension and broader beamwidth as well as wider bandwidth.     

Electromagnetic coupling reduction in dual-band microstrip antenna array using ultra-compact single-negative electric metamaterials for MIMO application

In this paper, an ultra-compact single negative(SNG) electric waveguided metamaterial(WG-MTM) is first investigated and used to reduce the mutual coupling in E H planes of a dual-band microstrip antenna array. The proposed SNG electric WG-MTM unit cell is designed by etching two different symmetrical spiral lines on the ground, and has two stopbands operating at 1.86 GHz and 2.40 GHz. The circuit size is very compact, which is only λ_0/33.6 ×λ_0/15.1(where λ_0 is the wavelength at 1.86 GHz in free space). Taking advantage of the dual-stopband property of the proposed SNG electric WG-MTM, a dual-band microstrip antenna array operating at 1.86 GHz and 2.40 GHz with very low mutual coupling is designed by embedding a cross shaped array of the proposed SNG electric WG-MTM. The measured and simulated results of the designed dual-band antenna array are in good agreement with each other, indicating that the mutual coupling of the fabricated dual-band antenna array realizes 9.8/11.1 d B reductions in the H plane, 8.5/7.9 d B reductions in the E plane at1.86 GHz and 2.40 GHz, respectively. Besides, the distance of the antenna elements in the array is only 0.35 λ_0(where λ_0 is the wavelength at 1.86 GHz in free space). The proposed strategy is used for the first time to reduce the mutual coupling in E H planes of the dual-band microstrip antenna array by using ultra-compact SNG electric WG-MTM.     

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.     

Theoretical study of 2 X 2 element planar array of equilateral triangular patch microstrip antenna in plasma medium

The radiation properties of 2 X 2 element planar array of equilateral triangular patch microstrip antenna in plasma medium are studied. The array factor and far-zone EM-mode and P-mode radiation fields of the array geometry are derived using vector wave function techniques and pattern multiplication approaches. The total field patterns and various characteristics of pattern such as half power beam width (HPBW), first null beam width (FNBW) and direction of maximum radiation are computed for two different values of progressive phase excitation difference between the elements. The results of this array geometry are obtained both in plasma medium and in free space and compared with those of single element equilateral triangular patch microstrip antenna.     

含有左手介质双层基底的亚波长谐振腔微带天线研究

将谐振腔引入微带结构,分析和设计了含有左手介质双层基底的亚波长谐振腔微带天线.基于左手介质对右手介质的相位补偿效应,此新型微带天线的高度并没有因为双层基底而大为增加,反而有所降低.计算表明：在一些情况下,大幅度提高的带宽特性突破了传统微带天线的窄带局限,而在另一些情况下,所得到窄带微带天线能够在单频率点谐振鉴频.针对这一特性,将亚波长谐振腔微带天线应用于探测器中,显示了此新型微带天线在目标探测上的优势. 关键词： 微带天线 左手介质 谐振腔     

A conical microstrip antenna with uniform substrate

A novel conical microstrip antenna with uniform substrate is investigated. The far field radiation patterns of wraparound microstrip antennas mounted on such a structure are studied theoretically. Results for a wraparound antenna of half-wavelength in width excited by TM₀₁ are given, which are verified accurate and efficient by the ones of wraparound cylindrical antennas when the cone angle is very small.