共查询到20条相似文献,搜索用时 0 毫秒
1.
A. Mehta D. Mirshekar-Syahkal 《Electronics letters》2007,43(9):491-493
A novel form of square loop antenna for beam adaptive applications is presented and analysed. The square loop has four feeding points, which when excited one at a time steer the beam in four different space quadrants. Using current distribution a qualitative explanation for the radiation mechanism is also presented 相似文献
2.
3.
4.
《Electronics letters》2005,41(16):47-48
5.
RongLin Li Laskar J. Tentzeris M.M. 《Microwave and Wireless Components Letters, IEEE》2006,16(1):52-54
A broadband circularly polarized rectangular loop antenna is developed. The broadband performance is achieved by adding a pair of parasitic loops inside the rectangular loop. Good impedance matching is obtained by introducing a broadband balun. The proposed rectangular loop has a bandwidth of 46% for axial ratio/spl les/2dB and 50% for VSWR/spl les/2 with a gain of around 8dBi. 相似文献
6.
7.
A low-profile circularly polarized (CP) antenna with high gain and broad bandwidth is aimed at 5-GHz Wi-Fi applications using a symmetrical E-shaped patch. Initially, the radiating element is modeled as a symmetrical E-shape. An array of 4 × 4 rectangular patches are arranged periodically to make up a reactive impedance surface (RIS) structure. Furthermore, the RIS structure is deployed in the middle of a symmetrical E-shaped radiating patch and a perfect electric conductor (PEC) ground plane. As a result, the broadband CP is achieved with high gain. The above-mentioned combinations have achieved a −10-dB reflection coefficient bandwidth of 21.4% (4.92–6.1 GHz) and a 3-dB axial ratio (AR) bandwidth of 15.5% (5.25–6.1 GHz), and the antenna has attained a gain of 7.45–7.53 dBic. 相似文献
8.
Simple closed formula is given to determine the resistive part of the loop antenna input impedance. An equivalent transmission line is used to determine the reactive part of the input impedance for the same loop, and the antenna in both cases may have any regular configuration. This method has proved to be accurate for a loop perimeter up to0.5 lambda for the resistive part and up to0.8 lambda for the reactive part. 相似文献
9.
Using a quasistatic approach, the input impedance of a circular wire loop is calculated for the case where the Earth is represented as a homogeneous conducting halfspace. It is shown that the input resistance is only proportional to the ground conductivity when the loop radius is small compared with the electrical skin depth. 相似文献
10.
Monacelli B. Pryor J.B. Munk B.A. Kotter D. Boreman G.D. 《Antennas and Propagation, IEEE Transactions on》2005,53(2):745-752
A frequency selective surface (FSS) was designed to have a resonant spectral signature in the infrared. The lithographically composed, layered structure of this infrared FSS yields a resonant response in absorption to infrared radiation at a wavelength determined by its FSS element structure and the structure of its substrate layers. The infrared spectral characteristics of this surface are studied via Fourier transform infrared spectroscopy and spectral radiometry in the 3 to 15 /spl mu/m region of the spectrum. The design is based on circuit-analog resonant behavior of square loop conducting elements. 相似文献
11.
基于全息光学原理,提出并设计了一种加载相位调制的毫米波圆极化全息天线,天线由电小尺寸的人工阻抗单元按表面阻抗分布参数排列而成。利用横向谐振技术分析了标量人工阻抗单元表面阻抗的计算方法,建立了单元尺寸与表面阻抗之间的数据库。给出了干涉表面的阻抗分布参数计算方法,通过加载相位调制,实现了全息天线的圆极化。利用Matlab-HFSS联合建模仿真,建立了毫米波圆极化全息天线的基本模型,仿真结果表明,天线工作于35 GHz,波束沿法向偏转35°,中心的轴比小于1.5 d B。 相似文献
12.
A periodic resonant texture can transform a conductive sheet into a high-impedance surface. By adjusting the resonance frequency using varactor diodes, the surface impedance and the reflection phase are tuned. The reflection phase can be varied across the surface, to create an electronically tunable phase gradient, which can steer a reflected beam in two dimensions. 相似文献
13.
A. N. Dement’ev D. S. Klyuev S. A. Shatrov 《Journal of Communications Technology and Electronics》2017,62(5):496-501
A method for calculating the input impedance of a loop antenna (LA) located on a dielectric cylinder is developed. The integral equation (IE) for the unknown function of the current density distribution on the LA surface is obtained. A numerical method for the IE solution is described. An approximate formula for calculation of the LA input impedance is proposed. Plots of the input impedance on the LA length are given. 相似文献
14.
用扫频仪测量天线的输入阻抗时,在同轴传输线与天线间应按平衡—不平衡变换器。针对圆环天线的输入阻抗为复阻抗,提出了一种新的四分之一波长平衡一不平衡变换器,得到了实验结果,并进行了讨论。 相似文献
15.
Closed-form expressions are derived for the input impedanceZ of a small loop antenna with arbitrary orientation in a cold collisionless uniform multicomponent magnetoplasma. The closed-forms results ofZ are compared with numerical results from a full-wave formal solution. It is found that for small loops these approximate formulas adequately represent the loop input impedance. 相似文献
16.
17.
The problem of a horizontal loop antenna located above a stratified dissipative half-space is investigated. Current distribution is formally obtained by cosinusoidal expansion around the loop. The effect of the lower half-space on each modal current is discussed in the case of a small loop (k_{0}b = 0.3 ) and a resonant loop (k_{0}b = 1 ). Change in input admittance as a function of height and as a function of the electric parameters of a homogeneous dissipative haft-space are presented. Such change is found to be very pronounced when the loop is close to the interface and when the loop is near resonance. The effect of a second layer in the lower half-space is then discussed. 相似文献
18.
A new efficient technique for the analysis of corrugated surface wave antennas with infinite ground plane fed by a parallel-plate waveguide is presented, termed the hybrid method of moments/uniform geometrical theory of diffraction (MOM/UTD) technique. The relative power pattern obtained using the method is compared with the patterns obtained from the previous approximate solution and experiment. The power pattern of the presented method agrees more closely with that of the experiment, compared with that of the previous approximate solution 相似文献
19.
20.
It is demonstrated, via the equivalence principle, that if the aperture fields are known, one can explicitly obtain the equivalent current excitation required for modeling an aperture in an arbitrarily shaped impedance surface, when the aperture surface is closed, by replacing it with an impedance surface. It is also demonstrated that the impedance condition over the antenna body and the closed aperture can be nonuniform and anisotropic and that different choices are possible for the value of the surface impedance of the surface that closes the aperture. It is expected that the procedures described will be most useful in approximately modeling aperture antennas embedded in nonplanar impedance surfaces where the aperture electric field is known. 相似文献