Dual-frequency stacked annular-ring microstrip antenna

Experimental results of a dual-frequency microstrip antenna consisting of two stacked annular rings of outer radii 5 cm and inner radii 2.5 cm are presented. Fabricated on a Duroid substrate with relative permittivity 2.32 and thickness 0.159 cm, the separations of the two resonant frequencies range from 6.30-9.36 percent for the first three modes. The frequency separations can be altered by means of an adjustable air gap between the lower ring and the upper substrate.     

Frequency independent microstrip stacked antenna

The advancement of technological development in the microstrip antenna and its applications in diverse areas, have given rise to the need for a frequency agile and frequency independent microstrip antenna which could be used for the same range of frequencies without altering the system. Requirements of such nature could be met by log periodic antenna. However, in the present endeavour a frequency independent microstrip stacked antenna consisting of nine elements operating in the S-band (2.000–4.000GHz) has been proposed. The developed antenna has been experimentally tested over an achievable band of frequencies from 3.200 to 3.920GHz. The antenna performance has characteristics like E-plane radiation patterns. The 3dB beamwidth, radiated power and VSWR show very similar behaviour for the different frequencies of operation obtainable in the S-band. The coaxial-fed microstrip stacked antenna provides an operational bandwidth of approximately 23%, i.e. 3.200GHz to 3.920GHz. The VSWR for the entire operational band is around 2 whereas the gain for the antenna is found to vary from 4.00 to 8.36dB. The 3dB beamwidth has been found to fluctuate between 16.8° and 23.5°. The designed antenna can be well suited for the practical broadband applications.     

Proximity-coupled U-slot patch antenna

The design and experimental results of a proximity-coupled U-slot microstrip antenna are presented. The impedance bandwidth (VSWR⩽2) of the antenna is 20%, centred at 4.3 GHz. It has an average gain of 7.5 dBi and a cross-polarisation of about -20 dB. Both gain and radiation patterns were measured across the passband. An essential feature in the design is that a Π-shaped feed line is connected at the end of the usual microstrip line     

Multifrequency microstrip patch antenna using multiple stacked elements

A multifrequency microstrip patch antenna comprised of a driven patch and a plurality of parasitic elements placed underneath a driven patch is proposed. The antenna features a multifrequency behavior (five operating band) with similar gain.     

Input impedance of a probe-fed stacked circular microstrip antenna

The input impedance of a microstrip antenna consisting of two circular microstrip disks in a stacked configuration driven by a coaxial probe is investigated. A rigorous analysis is performed using a dyadic Green's function formulation whereby the mixed boundary value problem is reduced to a set of coupled vector integral equations using the vector Hankel transform. Galerkin's method is used in the spectral domain, using two sets of disk current expansions. One set is based on the complete set of orthogonal modes of the magnetic cavity, and the other uses Chebyshev polynomials with the proper edge condition for the disk currents. An additional term is added to the disk current expansion to model the current properly in the vicinity of the probe/disk junction. The input impedance of the antenna, including the probe self-impedance, is calculated as a function of the layered parameters and the ratio of the two disk radii. Disk current distributions and radiation patterns are presented. The calculated results are shown to be in good agreement with experimental data     

Broadband matching of dual-linear polarisation stacked probe-fed microstrip patch antenna

A novel approach for impedance matching of probe-fed, stacked microstrip patch antenna elements is demonstrated. The matching structure is compact and enables more than doubling of the operational bandwidth. A circuit model for the feeding probes is developed and its impact on antenna impedance is discussed.     

Dual polarization stacked microstrip patch antenna array with verylow cross-polarization

This paper describes the development and performance of a wideband dual linear polarization microstrip antenna array used in the Danish high-resolution airborne multifrequency polarimetric synthetic aperture radar, EMISAR. The antenna was designed for an operating frequency of 1.25 GHz±50 MHz and was built as an array of 8×2 probe-fed stacked microstrip patches. The feeding network is constructed in microstrip and is capable of handling 6 kW of peak input-power at an altitude of 45000 ft (unpressurized). The impedance bandwidth (return loss better than -14 dB) of the antenna is 10%, the isolation between the horizontal and the vertical ports of the array is 50 dB and the cross-polarization suppression is 40 dB. A new design principle for simultaneously achieving very low cross-polarization and low side lobes in dual linear polarization antenna arrays has been applied     

Impedance of a circular-disc printed-circuit antenna

The driving-point impedance of a printed-circuit antenna consisting of a circular disc separated by a dielectric from a ground plane is investigated experimentally. The impedance is measured as a function of the operating frequency for various disc diameters, thicknesses and permittivities of the dielectric and feed point positions. In addition, a theoretical parallel RLC circuit model is proposed and compared with the experimental data.     

基于MATLAB和HFSS的叠层微带天线优化设计

提出了基于MATLAB和HFSS协同仿真优化设计天线的思路,并以叠层微带天线为例开发了相应的设计软件。利用MATLAB GUI编写了软件的操作界面,通过输入天线的技术指标,进行天线各参数的计算,利用生成的VBScript脚本文件调用HFSS进行快速建模仿真,并通过调用外部优化算法进行天线的最优化设计。该软件提高了叠层微带天线的设计效率,为天线的教学与科研工作提供了有效的辅助工具。     

一种天线馈源用宽带孔径耦合层叠微带贴片阵的设计

介绍了一种宽带孔径耦合层叠微带辐射单元的工作原理,着重分析了该辐射单元主要结构尺寸对其阻抗带宽的影响。该辐射单元阻抗带宽（VSWR≤2：1）在S波段达到了30％以上。作为某抛物反射面天线的馈源,由4个该辐射单元组成四单元微带贴片天线阵后,其性能满足天线系统要求。     

A broadband aperture-coupled stacked microstrip antenna with both patches notched and offset

This paper proposes a new approach to further improving the bandwidth of a typical aperture-coupled stacked microstrip antenna by cutting triangular notches in the radiating sides of both radiating patches together with offsetting both patches. An antenna applying this new approach is designed, fabricated, and tested. The experimental antenna could achieve a measured impedance bandwidth of about 37.5% for the Voltage Standing Wave Ratio （VSWR） 〈 2 in X-band.     

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.     

Self-adjusting microstrip antenna

A microstrip circuit operating in the G band is presented. It allows all emitting printed antenna to self-tune its resonance frequency when it is disturbed, in order to stay resonant and matched at the desired transmit frequency. The principle, design and experimental results of the circuit are presented     

A novel lightweight dual-frequency dual-polarized sixteen-element stacked patch microstrip array antenna for soil-moisture and sea-surface-salinity missions

The main motivation for this paper is to discuss the development of a novel compact and light-weight dual-frequency, dual linearly polarized, high-efficiency, stacked-patch microstrip-array antenna for use in standalone aircraft-based remote sensing applications. Results from simulation, fabrication, and testing of a sixteen-element stacked-patch array antenna, optimized for an L-band frequency of operation, are presented. The design center frequencies were 1.26 GHz and 1.413 GHz with 10 MHz and 25 MHz bandwidths in each band, respectively. Due to the large number of design parameters and demanding design requirements of beam-efficiency, sidelobe levels, and polarization characteristics, particle-swarm optimization (PSO) and finite-difference time-domain (FDTD) simulations were used for synthesis and analysis. Cancellation techniques, based on symmetry, were applied to the antenna ports, with a custom-built feed network to reduce cross polarization. Simulations and measurement results from a spherical near-field test facility confirmed excellent performance of the array configuration, with a beam efficiency of greater than 90%, isolation better than -35 dB, and cross polarization in the main beam of the array better than -40 dB. From the sixteen-element array simulations and experimental verifications, one of the objectives of the present study is to suggest the possibility of using customized dual-frequency, dual-polarized arrays as potential feeds for reflectors to replace the traditionally used conical horns for future soil-moisture and sea-salinity missions     

Center-fed microstrip patch antenna

A novel feeding scheme for microstrip patch antennas is presented, which consists of a coaxial probe and shorting pin separated by a narrow slot centrally cut at the radiating patch. The impedance and radiation characteristics of a conventional probe-fed microstrip patch antenna and the proposed microstrip patch antenna are experimentally examined and compared. The effects of the slot length on the antenna operation are also discussed.     

Dual frequency microstrip antenna

A single-feed dual-frequency microstrip antenna is reported. It can be impedance-matched independently at the two frequencies of operation. The tested antenna has a VSWR of 1.33 at 2.32 GHz and 1.12 at 9.425 GHz. The configuration reported here can be impedance matched over a wider frequency range using standard impedance-matching techniques.     

Dual-polarised wideband microstrip antenna

A dual-polarised aperture-coupled microstrip antenna with a wide bandwidth, a high isolation, low cross-polarisation levels and low backward radiation levels is presented. The square patch is fed at two corners via H-shaped apertures. The measured return loss exhibits a bandwidth of over 24.4% and the isolation is better than 30 dB over the bandwidth. The cross-polarisation levels and the front-to-back ratio are better than -23 and 22 dB, respectively     

Compact two-port microstrip antenna

A compact two-port array antenna which operates in the X-band is described. This antenna, which combines a high gain with a relatively wide bandwidth, was conceived using mutual coupling and parasitic coupling techniques. The analysis and the simulations performed using the transmission line method and matrix algebra are briefly presented     

Planar dual-band microstrip antenna

A novel dual-band microstrip antenna is introduced. The entire structure is planar and can be easily mass-produced by using printed-circuit technology. The antenna consists of multiple layers with metallic strips placed at one of the dielectric interfaces under the radiating patch. The resonant frequencies can be selected over a wide frequency range, and the impedance matching at those two frequencies is relatively simple. The physically intuitive cavity model is used for the analysis. A relatively simple design scheme is included     

Compact triangular microstrip antenna

Loading a triangular microstrip antenna with a shorting pin can significantly reduce the antenna size at a given operating frequency. Experimental results of such a triangular microstrip antenna are presented. Variations of the resonant frequency of the triangular microstrip patch with different shorting-pin positions are given, and comparisons of the compact and conventional triangular microstrip antennas are also presented and discussed