Hybrid-coupled shorted rectangular microstrip antennas

Hybrid-coupled (both gap and direct) shorted rectangular microstrip antennas have been investigated. Only one patch is fed and the other patch is parasitically coupled along the radiating and the non-radiating edges, respectively. Dual frequency and broadband operation has been obtained by optimising the coupling between the two patches through a copper strip     

Compact broadband E-shaped microstrip antennas

A broadband E-shaped microstrip antenna is discussed. Its bandwidth is further increased by cutting a pair of tapered slots. Using the even-mode symmetry of an E-shaped microstrip antenna, a compact single slot loaded rectangular microstrip antenna is proposed, which reduces the antenna size by half.     

Compact broadband S-shaped microstrip antennas

A compact and broadband stacked S-shaped microstrip antenna with corner shorted square microstrip antenna is proposed. A broadband slotted S-shaped microstrip antenna is also proposed which does not require any parasitic patches.     

Two-layer five-patch broadband microstrip antennas

An aperture coupled five-patch broadband microstrip antenna which makes use of stacked and coplanar techniques is studied. It is demonstrated that the antenna can attain a bandwidth of ~45%. The radiation patterns and SWR of the antenna are presented. A comparison between theoretical and experimental results is made     

Compact shorted variations of triangular microstrip antennas

Equilateral and triangular 30°-60°-90° microstrip antennas have been modified by shorting along the zero field to yield shorted 60 and 30°-sectoral microstrip antennas, respectively. Experimental results on these antennas are presented. The shorted 60 and 30°-sectoral antennas result in area reduction by factors of 2.5 and 5.0, respectively, compared to the equilateral triangular antenna with the same resonant frequency. The frequency is further reduced by partially shorting the curved edges of the sectoral antennas     

Experimental study on stacked triangular microstrip antennas

The broadband behaviour of a pair of stacked triangular microstrip antennas is investigated experimentally. Recent experiments have shown that the bandwidth of a triangular microstrip antenna (TMA) can be broadened to as high as 17.5%.     

Shape optimisation of broadband microstrip antennas using geneticalgorithm

The genetic algorithm (GA) is used to design patch shapes for microstrip antennas on FR-4 substrate for broadband applications. Measurement results of the GA-optimised designs show good agreement with numerical prediction. The optimised patch design achieves a fourfold improvement in bandwidth when contrasted with a standard square microstrip antenna     

A BROADBAND FEEDING TECHNIQUE FOR MICROSTRIP PATCH ANTENNAS

In order to broaden the bandwidth of a microstrip patch antenna,a broadbandtwo-port feedingtechnique based on the principle of reactance compensation is suggested.The principle and some designguidelines are presented;the calculating model of a practical configuration as well as its parameteroptimization is demonstrated,followed by several kinds of test models With their experimental results.It isshown that this technique enables the VSWR bandwidth to be broadened to 2—3 or more times that of aconventional design for both linear and circular polarization operation.     

Mutual coupling between triangular microstrip antennas on acylindrical body

The full-wave solutions and measured results of mutual coupling coefficients between two cylindrical-triangular microstrip antennas are presented. Both E-plane and H-plane coupling cases are studied. Theory and experiment are in good agreement     

Low-profile design of dual-frequency and dual-polarised triangular microstrip antennas

A single-feed triangular microstrip patch antenna that can be operated at two distinct resonant modes is proposed. The two resonant modes can radiate an omnidirectional dipole-like pattern with linear polarisation and a broadside pattern with circular polarisation, respectively. To achieve the required frequency ratio of the two operating frequency bands, several designs of the proposed antennas with different substrate thickness and patch sizes are studied. In addition, these designs can easily obtain a 50 /spl Omega/ input impedance without any additional matching circuit. Details of the antenna design and obtained performance are presented.     

Novel dual-frequency and broad-band designs of slot-loadedequilateral triangular microstrip antennas

By loading properly arranged slots in an equilateral-triangular microstrip patch, novel dual-frequency and broad-band operations of a single-feed triangular microstrip antenna are presented. For dual-frequency operation, the proposed design is achieved by loading two pairs of narrow slots in the triangular patch, one embedded close to the side edges of the patch and the other inserted at the bottom edge of the patch. The obtained two operating frequencies are of same polarization planes and by varying the positions and lengths of the inserted slots at the bottom edge of the patch, a tunable frequency ratio of the two frequencies ranging from about 1.16 to 2.06 is obtained. Furthermore, it is found that by protruding a narrow slot out of the embedded slots close to the side edges, broad-band operation of the triangular microstrip antenna near its fundamental resonant mode can be achieved. Results show that the antenna bandwidth of the proposed broad-band design can be greater than 2.6 times that of a conventional triangular microstrip antenna. Details of the proposed dual-frequency and broad-band designs are described and typical experimental results are presented and discussed     

Circular polarised microstrip patch antennas for broadband and dual-band operation

A novel design of microstrip patch antennas for circular polarisation (CP) is proposed. As an example, two CP patch antennas are investigated: a broadband CP patch antenna and a dual-band CP patch antenna. The proposed structure can be achieved by embedding circular holes in the microstrip circular resonator. By changing the size and position of loaded holes, two orthogonal modes are simultaneously excited with equal amplitude and /spl plusmn/90/spl deg/ out of phase. Without any 90/spl deg/ phase-shifter, the proposed CP patch antennas are excited by single feed.     

基于遗传算法的单层宽频带微带天线优化设计

宽带微带天线,尤其是单层宽带天线的设计较为困难.然而U型和E型微带天线提示我们,通过适当去除传统微带天线表面一些特殊位置的金属部分,可以展宽天线带宽.本文阐述了该类天线的工作原理,并详细描述通过采用遗传算法作为优化工具,以及在程序中直接调用IE3D的求解器(MOM)进行计算、提取相关参数进行GA优化的全过程.通过对普通方形贴片微带天线的仿真和实验,我们得到的天线带宽是优化前天线带宽的3倍多,证明了方法的可靠性和高效性.     

Gradient-based adjoint-variable optimization of broadband microstrip antennas with mixed-order prism macroelements

This paper describes a new finite element method (FEM)-based adjoint-variable approach to design and optimization of planar microwave circuits using sensitivity analysis, with respect to small variations of their design parameters. The implementation is based on a specially developed class of mixed-order prismatic macroelements, suitable for an efficient analysis of planar microwave structures. Their use, combined with a simple probe feed model, not only reduces the overall computational effort but also facilitates a straightforward derivation of port parameter sensitivities. Explicit expressions are given for the adjoint solution and S-parameter sensitivity and the process is verified through the design and optimization of two slotted broadband microstrip patch antennas.     

Improved formulae for the resonant frequencies of triangular microstrip patch antennas

In this article, an improved formula for the effective side length (a _eff) of the equilateral triangular patch antenna is presented. The computed resonant frequencies for the first five modes, using this formula, are compared with the available experimental and theoretical results in the literature. It is shown that the proposed formula has better accuracy than other available expressions. Moreover, the 30°–60°–90° and 30°–30°–120° triangular patch antennas are studied. Specifically, improved formulae for the effective dielectric constant of these patches are derived.     

自主研发的智能宽频段天线

现有的无线电监测和测向天线，一直在沿用固定长度振子，或沿用以固定频段来分组的多层天线。这一做法存在种种缺陷；在同一监测塔上叠加很多组天线阵必然产生互耦；固定长度的天线还存在副瓣缺陷，影响测向的准确度；搬移式测向设备，人工调换天线振子很不方便，在北方冬季难以使用；天线振子的圆杆形状，对方向的选择性不强。这些缺陷必须加以克服，使测量手段向标准化方向迈进，才能卓有成效地开展工作。     

Conformal microstrip antennas and microstrip phased arrays

A new class of antennas using microstrips to form the feed networks and radiators is presented in this communication. These antennas have four distinct advantages: 1) cost, 2) performance, 3) ease of installation, and 4) the low profile conformal design. The application of these antennas is limited to small bandwidths. Phased arrays using these techniques are also discussed.     

CPW-fed stacked microstrip antennas

This paper presents a systematic parameter study of aperture-coupled stacked patch antennas fed by coplanar waveguide. These antennas are to be used at millimeter-wave frequencies in the 30-GHz range. The influence of the most important design parameters, such as patch dimensions, aperture dimensions, and substrate thicknesses, was studied extensively. It has been found that these antennas can easily be impedance-matched by tuning the dimensions of the excitation slot and adding a small tuning stub. In this way, an antenna element with a -10 dB impedance bandwidth of 36.8% has been designed. Furthermore, the results of this parameter study have allowed to formulate some general guidelines concerning the design of this type of antenna element.     

Small dual-frequency microstrip antennas

The characteristics of a dual-frequency compact antenna, which uses a rectangular microstrip patch with a shorting pin, are studied. Compared with the conventional rectangular patch antenna, this antenna can achieve both a significant reduction of antenna size and a dual-frequency operation with a single feed. A detailed parameter study is performed. The theoretical analysis is based on the finite-difference time-domain (FDTD) method. The FDTD codes are developed and validated by measurement results. One antenna has been designed and fabricated, and the comparisons between the measured results and the calculated results are provided. The effects of several antenna parameters on two resonant frequencies, frequency ratio, and radiation pattern characteristics of the antenna have been analyzed and compared. The results of the return loss are also presented. It is shown that various frequency ratios (2.82-4.23) can be obtained by varying the design parameters of this antenna. Several design curves are also presented     

Circular-waveguide-fed microstrip patch antennas

A microstrip patch antenna fed by a circular waveguide is presented. The microstrip patch built on a foam substrate is laid on the flange of the circular waveguide's open mouth. The waveguide feeds the patch by coupling energy to the patch through a narrow slot underneath the patch. Two operating frequency bands were observed and the characteristics of the antenna were measured.