低RCS栅格微带天线研究

研究了栅格微带天线在微带天线RCS减缩中的应用。分析了栅格线宽度、栅格线间距、栅格化方式等参数对天线的谐振频率、增益的影响。设计了一副具有低RCS特性的栅格微带天线,与谐振在同频率的微带贴片天线相比,天线的增益仅降低0. 6dBi,而天线在2~10GHz频带内的平均RCS降低4dBsm。     

Graphene Microstrip Patch Ultrawide Band Antennas for THz Communications

Future generation local communication systems will need to employ THz frequency bands capable of transferring sizable amounts of data. Current THz technology via electrical excitation is limited by the upper limits of device cutoff frequencies and by the lower limits of optical transitions in quantum confined structures. Current metallic THz antennas require high power to overcome scattering losses and tend to have low antenna efficiency. It is shown here via calculation and simulation that graphene can sustain electromagnetic propagation at THz frequencies via engineering the intra‐ and interband contributions to the dynamical conductivity to produce a variable surface impedance microstrip antenna with a several hundred GHz bandwidth. The optimization of a circular graphene microstrip patch antenna on silicon with an optimized return loss of ?26 dB, a ?10 dB bandwidth of 504 GHz, and an antenna efficiency of ?3.4 dB operating at a frequency of 2 THz is reported. An improved antenna efficiency of ?0.36 dB can be found at 3.5 THz but is accompanied by a lower bandwidth of about 200 GHz. Such large bandwidths and antenna efficiencies offer significant hope for graphene‐based flexible directional antennas that can be employed for future THz local device‐to‐device communications.     

The Characteristics of Iris-Fed Millimeter-Wave Rectangular Microstrip Patch Antennas

The fabrication of various iris-fed millimeter-wave rectangular microstrip patch antennas is described. A mathematical model is proposed to describe the iris-fed antenna. An iris having 15 percent of the area of the patch is used to couple energy into the antenna. Resonance of the antenna is observed to be insensitive to the size of the iris for irises up to 115 percent of the size of the patch. A study is also made of the coupling to the antenna as a function of position of the iris with respect to the transverse plane of the waveguide, the iris always being centered with respect to the patch. In general, the antenna has a VSWR in the waveguide feed of roughly 5:1 at resonance, except for the fully open waveguide which gives rise to a VSWR of 2.9:1 at resonance. Far-field antenna power patterns are observed to be quite broad with H-plane beamwidths about 130°. Maximum antenna gain observed was 4.5 dB relative to an isotropic source (dBi), with 2 dBi typical. An initial study is made of the microstrip patch antenna fed from a longitudinal waveguide wall. Results indicate that this feed structure is likely to prove valuable for microstrip patch antennas, with coupling at least as good as for the transverse-fed patch, added to the possibility of feeding multiple patches from a single waveguide.     

Dual Radial-Resonant Wide Beamwidth Circular Sector Microstrip Patch Antennas

In this article, a design approach to a radial-resonant wide beamwidth circular sector patch antenna is advanced. As properly evolved from a U-shaped d ipole, a prototype magnetic dipole can be fit in the radial direction of a circular sector patch radiator, with its length set as the positive odd-integer multiples of onequarter wavelength. In this way, multiple TM_0m(m = 1,2,...) modes resonant circular sector patch antenna with short-circuited circumference and widened E-plane beamwi...     

Dual-Polarized Microstrip Patch Planar Array Antennas With Improved Port-to-Port Isolation

A method of preventing the degradation in the isolation between the orthogonal polarization ports caused by beamforming network routing in combined edge/aperture fed dual-polarized microstrip-patch planar array antennas is described. The simulated and measured performance of such planar arrays is demonstrated. Measured port isolations of 50 dB at center frequency, and more than 40 dB over a 4% bandwidth, are achieved. In addition, insight into the physical reasons for the improved port-to-port isolation levels, of the proposed element geometry and beamforming network layout, is obtained through prudent use of the electromagnetic modelling.      

一种分析微带贴片天线的辛时域有限差分方法

文中研究了在时间上采用5级4阶差分、空间上采用4阶差分的高阶辛时域有限差9（SFDTD）数值方法。给出其三维差分公式．将吸收边界条件应用于微带天线的计算中，计算了微带贴片天线的回波损耗及输入阻抗等．计算结果证明，该方法的精确性和正确性．     

缝耦合微带双贴片天线阻抗和辐射特性

本文提出了将阵列单元由单贴片改成缝耦合双贴片的形式。利用并矢Ｇｒｅｅｎ函数和谱域矩量法分析了单贴片及缝耦合双贴片天线的输入阻抗。考虑了阵列天线的馈电网络中不均匀性的影响，根据解积分方程所得出的微带天线贴片表面电流分布。计算出其方向图特性，结果表明，缝耦合双贴片两单元微带阵列天线的阻抗频带提高到普通两单元微带阵列天线频带的２．５倍，文中实验数据与理论计算结果吻合甚好。     

Frequency Tunable Microstrip Patch Antenna Using RF MEMS Technology

A novel reconfigurable microstrip patch antenna is presented that is monolithically integrated with RF microelectromechanical systems (MEMS) capacitors for tuning the resonant frequency. Reconfigurability of the operating frequency of the microstrip patch antenna is achieved by loading it with a coplanar waveguide (CPW) stub on which variable MEMS capacitors are placed periodically. MEMS capacitors are implemented with surface micromachining technology, where a 1-mum thick aluminum structural layer is placed on a glass substrate with a capacitive gap of 1.5 mum. MEMS capacitors are electrostatically actuated with a low tuning voltage in the range of 0-11.9 V. The antenna resonant frequency can continuously be shifted from 16.05 GHz down to 15.75 GHz as the actuation voltage is increased from 0 to 11.9 V. These measurement results are in good agreement with the simulation results obtained with Ansoft HFSS. The radiation pattern is not affected from the bias voltage. This is the first monolithic frequency tunable microstrip patch antenna where a CPW stub loaded with MEMS capacitors is used as a variable load operating at low dc voltages     

60-GHz Patch Antennas and Arrays on LTCC With Embedded-Cavity Substrates

The design is presented of aperture-coupled microstrip line-fed patch antennas (ACMPAs) and 4$,times,$ 4 planar arrays on Ferro A6-S low-temperature cofired ceramic (LTCC) substrate operating in the 60-GHz frequency band. In addition to the traditional ACMPA design, air cavities processed inside the LTCC substrate are used to improve the bandwidth and gain of the antennas. The arrays are excited through the microstrip-line feed networks using quarter-wave matched T-junctions and using Wilkinson power dividers. The results show that ACMPAs and arrays can be fabricated with a standard LTCC process even for the millimeter-wave region. Good agreement is achieved between simulations and measurements. The measured S-parameters indicate impedance bandwidths of 9.5% and 5.8% for the array elements with and without an embedded cavity. The measured maximum gains for the 16-element patch arrays (with and without cavity) are 18.2 and 15.7 dBi, respectively.      

多短路针加载小型微带贴片天线的理论分析

与单短路针加载微带贴片天线相比，多短路针加载微带贴片天线具有较低的输入阻抗和较宽的频带。本文提出了多短路针加载微带贴片天线谐振频率、输入阻抗及回波损耗的计算方法，给出了相应的计算公式，并用这些公式对具体天线进行了计算，给出了计算结果，分析了天线谐振频率随第2根短路针位置和直径的变化规律。     

Theoretical Investigation of the Input Impedance of Gap-Coupled Circular Microstrip Patch Antennas

In this paper, we have explored a simple theoretical input impedance computation technique for the two gap-coupled circular microstrip patch antennas by using circuit theory approach. The frequency characteristics of the input impedance of the two gap-coupled circular microstrip patch antennas with the gap-distance between the feed patch and parasitic patch is analyzed and simulated. The effect of feed location in the feed patch on the input impedance of proposed antenna is also studied. The theoretical results are compared with the simulated results as well as other reported literature. The simulation has been performed by using a method-of-moment based commercially available simulator IE3D.     

A Circuit-Theoretic Approach to the Design of Quadruple-Mode Broadband Microstrip Patch Antennas

A novel method for the design of broadband patch antennas is described. The approach taken is to broadside couple two dual-mode patch antennas, resulting in a quad resonance antenna. The equivalent circuit of the antenna is similar to that of microwave filters, thus filter design techniques maybe employed to synthesize the antenna to obtain maximum return-loss bandwidth. This is the first time an increase in the bandwidth is achieved on a relatively thin substrate antenna as a result of coupling four resonant modes using two stacked circular microstrip patches. Electromagnetic simulation and measured results demonstrate bandwidth improvement of over four times that of a single-mode design.     

Rigorous Full-Wave Analysis of Rectangular Microstrip Patch Antenna on Suspended and Composite Substrates

In this paper, Galerkin’s method in the Fourier transform domain is applied to the determination of the resonant frequencies and half-power bandwidth of rectangular microstrip patch on composite and suspended substrates. Using Galerkin’s method in solving the integral equation numerically, the complex resonant frequency of the microstrip antenna on suspended and composite substrates is studied with sinusoidal functions as basis functions, which show fast numerical convergence. The validity of the solution is tested by comparison of the computed results with experimental data. Finally, numerical results for the effects of suspended and composite substrates on the resonant frequency and half-power bandwidth are also presented.     

反转容性探针馈电宽带圆极化微带天线的设计

设计了一款可用于UHF频段(915 MHz)RFID读写器的宽带圆极化微带天线,采用双层介质微带贴片展宽天线频带,馈电方式为反转容性探针馈电。贴片天线在工作频段内(902~928 MHz)性能优良,其中3 dB轴比带宽27 MHz;电压驻波比VSWR<1.5,带宽为120 MHz。并利用商业软件Zeland IE3d进行仿真设计和优化。     

角馈双极化微带贴片天线的辐射特性和极化特性研究

本文采用腔模理论导出了角馈双极化微带贴片天线的方向图表示式，并在此基础上分析了该天线的极化特性。结果表明角馈双极化微带贴片天线的两个不同极化并非处处正交，而是在有用的主瓣角度范围内，两个极化是接近正交的，而且采用多端口网络理论计算两馈电端口间的隔离度仍然大于20dB，因此角馈双极化微带天线能够用于极化分集接收。     

A New CMOS Multilayer Electromagnetic Band-Gap Microstrip Line and Experimental Investigation of UWB Pulse Propagation

We report on the development of a new microstrip line and Its experimental results on ultra-wideband pulse propagation. The transmission line employs electromagnetic band-gap (EBG) structures and is implemented in the multilayer metal stack of a 0.25-mum CMOS process. The inductance and capacitance per unit length of the new microstrip line can be independently adjusted to achieve various slow-wave factors for different characteristic impedances by properly selecting the dimensions of the EBG cells, their respective locations, and the CMOS metal layers. Experimental time-domain investigation of the pulse propagation reveals an interesting phenomenon of pulse compression. This unique property of the new CMOS multilayer EBG microstrip line can be exploited to help generate pico-second pulse as well as to compensate for the loss and dispersion of transmission lines, hence effectively retaining or enhancing the pulse propagation characteristics in UWB impulse circuits.     

基于小间距低耦合阵元的微带天线阵设计*

设计微带天线阵时,减小阵元间距会导致阵元间耦合增加,从而导致增益下降(在考虑口径增益减小的基础上进一步下降).针对该问题,提出一种减弱小间距阵元间耦合的新方法,即通过在地板上蚀刻两条共面波导,引入新的幅度可调的耦合去抵消原有耦合,从而实现减小阵元间耦合的目的.该方法将邻边间距为0.024λ0(λ0是自由波长,中心间距约0.38λ0)的阵元之间的隔离度(IS21I)从6.1dB提高到21dB以上,改善了阵元的辐射特性,使每个阵元的辐射方向图接近单个贴片的辐射方向图.为验证有效性,本文基于该方法设计了一副二元微带天线阵,并对其进行测试,与等口径面的二元阵比较,增益提高了约1.2dBi,与等增益的二元阵比较,面积减少了约10.2％,且副瓣电平有较大改善.     

Study of LDPE/TiO2 and PS/TiO2 Composites as Potential Substrates for Microstrip Patch Antennas

Low-density polyethylene (LDPE)/titania (TiO₂) and polystyrene (PS)/titania (TiO₂) composite systems have been developed as alternative substrates for microstrip patch antennas (MPA) for handheld devices. Morphological, thermal, and microwave characterizations of these composites have been conducted for different volume fractions of TiO₂ in the polymer matrix. The size of the titania particles was found to be of the order of 0.5 μm, and their distribution in the composite was quite uniform. Composite materials showed an improvement in thermal and microwave properties over the parent polymer. Verification of these composites as potential substrates for MPA was carried out by fabricating simple rectangular patch X-band antennas. Materials with optimized substrate properties were chosen to design the MPA. The patches were designed with 4% volume fraction TiO₂ in the LDPE composite system and 6% volume fraction TiO₂ in the PS composite system. Return loss of ∼18 dB was observed for both systems.     

一种新型宽带电磁带隙结构

该文研究了实现宽带EBG(Electromagnetic Band-Gap)结构的方法。仿真结果表明利用周期渐变技术可以明显增加阻带带宽,进而采用单元尺寸加窗技术可以改善通带和阻带的平坦度。在该文的例子中,-20dB的阻带带宽增加了2096以上,3GHz以下的通带插损小于0.4dB。制作了相应的实际电路,实验结果与仿真结果基本相符。     

偏心圆环微带天线谐振特性的研究

本文分析了偏心圆环微带天线ＴＭ１１模的谐振特性，理论值与实测值一致性较好，所用的方法适用于分析多个扇形环组合组的微带天线。