The synthesis of patterns using a series-fed array of annularsector radiating line (ANSERLIN) elements: Low-profile, circularlypolarized radiators

A series-fed, circularly polarized array of annular sector radiating-line elements that operates over a ground plane and has a low profile is presented. Pattern shaping can be achieved through control of the fraction of the incident power that is radiated by each element. This can be accomplished over a wide range by a simple adjustment in the geometry of each element. A synthesis technique is given, and experimental results are presented. The array is demonstrated to have a high return loss (good impedance match) and a low axial ratio     

宽带宽角圆极化贴片天线的实验研究

本文提出一种新的宽带宽角圆极化微带天线设计方法,在利用容性探针近耦合馈电的基础上,通过平衡馈电,使贴片天线的阻抗带宽(VSWR≤2)和宽角轴比带宽(45°圆锥空域内的AR≤3dB)达到20%以上.实验测试表明,利用该方法设计的贴片天线的带宽达到26.33%(VSWR、宽角AR同时满足要求),从而证实了该方法的正确性和实用性.     

Wideband double-element ring slot antenna

A new technique for bandwidth enhancement of microstrip-fed annular ring slot antennas is presented. Using this technique, a wideband antenna is designed that has consistent radiation parameters across the entire band and has a bandwidth that is six times larger than that of an ordinary ring antenna.     

THE MOMENT METHOD ON RESONANT QUADRIFILAR HELICAL ANTENNAS

An efficient measure is taken to rearrange Nakano's kernels of integral equationsfor an antenna system composed of arbitrarily bent wires.By means of the moment method,great efforts are made to analyze and compute the circularly polarized patterns,directivity,axialratio,front-to-back ratio and beam-shaping characteristics of resonant quadrifilar helical antennasas well as the feeding technique and the effect of an electrically large conducting body on theperformance of the antennas.     

Novel Broadband Circularly Polarized Cavity-Backed Aperture Antenna With Traveling Wave Excitation

A novel broadband circularly polarized aperture antenna is presented that uses traveling-wave excitation as the design concept. The antenna configuration consists of a circular radiating aperture, a backed cavity, and an equiangular tapered strip outer-fed by a microstrip transmission line. Operating with a traveling wave excitation, the proposed antenna contains inherent broadband characteristics in terms of the impedance, axial ratio, and gain performances. The presented antenna is comprehensively investigated, including the working principles, design consideration, and parametric studies. In addition, the research interests are extended to a 2$,times,$ 2 antenna array. Promising results from the experimental 2$,times,$2 array are achieved, including the 10-dB return loss bandwidth of 70%, the 3-dB axial ratio bandwidth of 50%, and the half-power (3-dB) gain bandwidth of 40% with a maximum gain about 11 dBi. The measured and simulated results are well complied with each other.      

Broadband quasi-microstrip antenna

A new printed microwave antenna is presented. The antenna is a hybrid between a wire antenna array and a microstrip patch antenna. Although the size, cost, and efficiency are comparable to the microstrip patch, the voltage standing wave ratio 2:1 bandwidth of the antenna presented here is above 20%. The radiation pattern of the antenna does not change appreciably within the bandwidth, and the theoretical efficiency for optimal antennas remains above approximately 80% within the bandwidth. Measurements on several antennas around 2 and 4 GHz are presented, as well as theoretical results obtained using a full-wave analysis     

Compact dielectric loaded circularly polarised microstrip antenna

An investigation into the novel dielectric loading technique for reducing the size of low profile microstrip antennas is presented. Inserting or loading discrete dielectrics into the air substrate of a microstrip patch antenna can considerably reduce the antenna size while at the same time achieve good bandwidth and excellent axial ratio performance. Experimental and simulated results at L-band frequencies demonstrate the effectiveness of this approach     

Analysis of circularly polarized square ring and crossed-strip microstrip antennas

Segmentation technique coupled with cavity model have been used to analyze square ring and crossed-strip microstrip patch antennas for circular polarization. This technique is found to predict the characteristics of antennas correctly, as is evident from the close agreement between the calculated and measured results for resonant frequency, input impedance, radiation patterns, and bandwidth. Square ring antenna has been found to have larger impedance bandwidth and axial ratio bandwidth because of lowerQ. Crossed-strip antenna has larger size and thus fabrication tolerances can be relaxed.     

Broadband printed circularly-polarised aperture antenna array for millimetre-wave gigabit applications

A simple and successful design of a printed aperture antenna array is presented in view of high-speed millimetre-wave wireless access applications. The antenna element design is based on a broadband travelling- wave aperture antenna for circularly-polarised radiation. For the antenna array design, the sequential rotation scheme is employed for improving the co-polarised gain and axial ratio. The presented antenna array is designed in the 40?48 GHz band and implemented with a 5mil-thick RT/Duroid-5880 PCB. Promising performances are achieved, including a return loss (,10 dB) bandwidth of 32%, an axial ratio (,3 dB) bandwidth of 25%, and a co-polarised gain (flatness , 3 dB) bandwidth of 32% with a maximum gain of 11dBic.     

Low-Cost Broadband Circularly Polarized Printed Antennas and Array

This paper presents the design, simulation, and measurements of two low-cost broadband circularly polarized (CP) printed antennas: an element and an array at 2 GHz. To realize the broadband circularly polarized antenna element, a circular microstrip patch is electromagnetically coupled by crossed slots cut in the ground plane, which is fed by an L-shaped microstrip feed. Two orthogonal modes in the patch are excited by using the crossed slots, and a single L-shaped feed provides a 90deg phase shift between two orthogonal slots. The antenna element achieves a 9.6% bandwidth for an axial ratio (AR) below 3 dB and a voltage standing wave ratio (VSWR) below 1.5. To further improve the performance, a sequentially rotated feed network is designed for a 2 times 2 array. The axial ratio value of the array is below 3 dB within a 27.2% bandwidth, from 1.75 GHz to 2.3 GHz. The return loss is above 10 dB within a 41% bandwidth, from 1.62 GHz to 2.45 GHz. Details of the proposed antenna element and the array design are described, and both the simulation and the experimental results are presented and discussed.     

Mesh antennas for dual polarization

Three mesh antennas, all having an extremely small antenna height of approximately 0.06 wavelength above a ground plane, are presented. First, a mesh antenna excited with a balanced feed is analyzed. It is revealed that the mesh antenna radiates a linearly polarized wave with no cross-polarization component in the principal planes. The radiation mechanism is explained using the current distribution. Second, a mesh antenna excited with an unbalanced feed is analyzed. This antenna shows almost the same radiation characteristics as the mesh antenna with a balanced feed. The frequency bandwidth for a VSWR=2 criterion is evaluated to be approximately 3%. Third, a mesh antenna having two perturbation elements is analyzed. It is found that the antenna acts as a radiation element of circular polarization. The frequency bandwidth for a 3-dB axial ratio criterion is calculated to be approximately 1%. The mesh antennas in the first and second analyses can be used as dual linear polarization elements by appropriately switching the feed. Similarly, the mesh antenna in the third analysis can be used as a dual circular polarization element by switching the feed     

C-figured loop antennas

C-figured loop antennas are analysed numerically. The current distribution, radiation pattern and axial ratio are presented. It is found that the c-figured loop antennas radiate a circularly polarised wave with a relatively wide 3 dB axial ratio bandwidth (~5%)     

Pattern distortion of aperture antennas radiating in the presence of conducting platforms

An analytically simple and numerically efficient technique for calculating the pattern distortion of aperture antennas radiating in the presence of conducting platforms located in the near or far field of the antenna is presented. The technique presented, based on uniform geometrical theory of diffraction (UGTD), is also applicable for large aperture antennas (aperture area> 15 lambda^{2}). An excellent agreement between the calculated and measured results obtained for a typical aperture antenna mounted on a conducting platform confirms the validity of the analytical technique developed.     

Experimental study of wideband printed annular slot antenna with cross-shaped feedline

A annular slot antenna with cross-shaped feedline has been investigated experimentally to obtain a large bandwidth enhancement. The voltage standing wave ratio (VSWR), radiation pattern, and antenna gain of this configuration are presented. Although the use of a high relative permittivity (/spl epsiv//sub r/=4.3) substrate usually restricts the operation bandwidth, the radiation resistance also was a low value. The measured bandwidth is /spl sim/ 108.4% (2.0 /spl ges/ VSWR).     

The double-helix antenna and its variants, a new class of tunable endfire antennas

Endfire antennas develop maximum gain when the phase velocity of the surface wave traveling along the structure is adjusted to its optimum value determined as a function of antenna length and operating frequency. These antennas usually have a relatively small pattern bandwidth and, if maximum gain is desired, can be used over only a small frequency range. The antennas described in this paper inaugurate a new class of antennas that are tunable for maximum gain in the endfire direction over a wide frequency range; tuning is accomplished by changing the phase velocity continuously or in prescribed steps. Such antennas include certain configurations of the double helix (a novel type of endfire antenna) and its artificial and natural dielectric variants. Useful structures are obtained through parallel displacement of two juxtaposed elements or angular displacement of a scissors arrangement. Model measurements show that maximum gain can be obtained over a frequency range of more than 2:1. Tuning effects are illustrated in detail by means of near-field plots of a tuned dielectric antenna.     

Single-feed circularly polarized microstrip ring antenna and arrays

An analysis is presented for a microstrip-feed proximity-coupled ring antenna and a four-element array. Interactions between the embedded microstrip feed and the radiating element(s) are rigorously included. Results demonstrate that circular polarization of both senses can be achieved with a ring antenna with proper design of two inner stubs located at angles of ±45° with respect to the feedline. Theory and experiment demonstrate an axial ratio 3-dB bandwidth of 1% and the voltage standing wave ratio (VSWR) <2 bandwidth of 6.1%. The axial ratio bandwidth is typical for a microstrip antenna with perturbations, while the VSWR bandwidth is larger than for the circular or rectangular patch with perturbations. A mutual coupling study between two elements shows that the axial ratio is less than 2 dB for interelement spacing greater than 0.55λ_eff, while the VSWR <2 for all spacings considered. A comparison between theory and experiment is provided for a 2×2 element array. The benefits of sequentially rotating the antenna elements in an array environment are presented. The axial ratio and VSWR bandwidths are both increased to 6.1% and 18% for a four-element array. A single-element antenna with two orthogonal feeds to provide both senses of polarization is demonstrated. The ring antenna is small (D/λ₀=0.325), the substrate thickness is thin (H/λ₀~0.035), and the microstrip feed produces a completely planar antenna system, which is compatible with microwave and millimeter integrated circuits (MICs), and monolithic microwave integrated circuits (MMICs)     

一种新型环状宽带圆极化微带天线设计

本文设计了一种新型的环状开缝的宽带圆极化微带贴片天线,通过等幅度90°相位差的L型探针馈电。通过在环状贴片上开槽可以有效的增加轴比和阻抗带宽。传统的圆极化天线带宽受限于阻抗、轴比和增益的公共带宽,本文提出的天线得到有效带宽从1.1GHz到1.9GHz,相对带宽达到了53%以上,频带覆盖了GPS、GALILEO、COMPASS、GLONASS四大导航系统。该天线性能较好,加工调试简便,在卫星导航等领域具有广阔的应用前景。     

A printed hemispherical helical antenna for GPS receivers

A self-matched printed hemispherical helical antenna for potential use in global positioning system receivers is introduced. Unlike wired hemispherical helical antennas, its printed form renders it a much more stable and endurable structure and also easier for fabrication. The optimized antenna shows an impedance bandwidth of 6%, a 3-dB axial ratio bandwidth of 6%-7%, a return loss greater than 20 dB, and a gain of about 9 dB at the center frequency. The patterns of the antenna show a larger mainlobe in the upper half space with relatively small backlobes. Both theoretical and experimental results was presented.     

Broad-band gap coupled microstrip antenna

A microstrip antenna with large bandwidth is developed using a parasitic technique. Compared to the available wideband antennas, the proposed antenna structure is very compact and gives a less distorted radiation pattern with frequency. An impedance bandwidth eight times that of a conventional patch antenna of the same size is achieved. The concept of coupled microstrip line model is extended for theoretical interpretation of the impedance loci. The experimental procedure and results are described, and a theoretical analysis is presented     

用于超宽带技术的二元螺旋天线阵研究

分析了螺旋天线的研究方法,讨论了单个螺旋天线元实现宽带与提高增益的矛盾,并提出了相应的改善方法。用多层介质板集成2个辐射区直径不同的螺旋天线以获得低驻波比和宽频带,而且还对这种螺旋天线的增益和驻波比如何受其尺寸大小变化进行了研究,使得这种改进型的螺旋天线能够克服单个天线的缺点,在保证较好增益的前提下实现超宽带。利用著名的仿真软件HFSS10.0和ADS2005进行仿真设计和优化,最终仿真设计了一副适用于超宽带通信系统的微带天线。