Scanning characteristics of infinite arrays of printed antennasubarrays

The analysis and scanning characteristics of several different types of infinite arrays composed of subarrayed printed dipole and microstrip patch elements are presented. The analysis is based on full-wave moment method theory, and includes mutual coupling between elements in the subarray as well as between subarrays. The effect of subarraying on scan blindness is demonstrated for arrays using two-element subarrays of printed dipoles and microstrip patches. Results are also given for the amount of power radiated in grating lobes. The effect of a subarray composed of one driven element and one parasitic element, and the use of a four-element synchronous subarray of microstrip patches to generate circular polarization are also considered. Data are given for impedance mismatch, power radiated into grating lobes, and the axial ratio; both square and rectangular patches area considered. Results are also shown for an infinite array of seven-element hexagonal subarrays of printed dipoles, and it is found that the large spacing between subarrays leads to a limited scan range     

A Circularly Polarized Stacked Patch Aperture Coupled Microstrip Antenna for 2.6 GHz Band

A circularly polarized stacked patch microstrip antenna and a 2?×?2 subarray for circular polarization are proposed in this paper. The proposed design has the input impedance bandwidth and axial ratio bandwidth of about 10% and 4.7% respectively. Circular polarization is obtained with the help of slits cut in the patch. A size reduction of around 37% is also achieved with the help of the slits. A subarray based on sequentially rotated feeding technique for circular polarization is also presented in this paper. Array element was deigned using a high dielectric constant laminate for feed network. In addition to low boresight axial-ratio, the subarray has impedance and 3-dB axial-ratio bandwidths of 12% and 8% respectively.     

Cross-polarization tolerance requirements of square microstrippatches

We normally feed a rectangular patch along the centerline of the H-plane (the non-resonant width). This is done to eliminate excitation of the patch in a mode along the other axis. The second mode radiates cross polarization. This article provides the tolerance requirements, given the cross polarization. The rectangular microstrip patch radiates its peak cross polarization in the diagonal planes, even when the antenna is fed perfectly. This cross polarization is low. When we locate the feed along the centerline of the H-plane of the patch, the impedance match to the TM₀₁ mode is poor, and the antenna does not radiate significant power at boresight to the patch. Often we design a square patch, so that we can radiate orthogonal-linear polarizations (or dual-circular polarizations) by using two feeds. If we fail to place the feed probe, aperture, or microstrip line along the H-plane axis, the cross-polarization level rises     

一种毫米波一维单脉冲圆极化微带天线的研究

本文设计了一种毫米波双魔T 结构的单脉冲右旋圆极化微带阵列天线。针对微带天线经典“H”形馈电类型在单 元间距较小时不再适用的问题,设计混合馈电网络以减小馈线与贴片单元的互耦,并在天线背面采用双魔T 结构的波 导和差网络馈电。这种结构设计在一定程度上减小了馈电插入损耗。为减小平行长馈线间耦合,采用了在两级馈电网 络间加隔离贴片的方法,有效地隔离了平行馈线间的耦合,消除部分表面波影响,保证了功率分配。仿真结果与实测 结果吻合较好。     

Optimization of microstrip feed geometry for prime focus reflectorantennas

The radiation characteristics of a circular microstrip antenna are studied numerically. Surface integral equations are used to formulate the problem from the boundary conditions and moment methods are used to reduce the integral equations to a matrix equation. An analytic method is used to design a microstrip feed and to achieve symmetric radiation patterns with low cross polarization and backlobe levels. The backlobe level is reduced by adding a quarter-wavelength choke to the side wall or the ground plane of the antenna and the bandwidth is improved by stacking two layers. The performance of the feed with the reflector antenna is also considered. One of the feeds was fabricated and tested. Satisfactory agreement between the computed results and the measurement data was obtained. The microstrip feed has a very small size which should reduce its blockage of the reflector aperture     

小型多馈源宽频微带天线分析与设计

本文着重研究了提高轴比带宽的方法。从多馈源实现圆极化的机理出发,从理论上分析证明了采用多馈源技术可有效展宽轴比带宽。在小型微带贴片天线上,设计馈电网络,采用探针馈电,为贴片提供等幅、相位相差90°的激励,形成圆极化。仿真及实测结果表明,这种天线与单馈点天线相比,展宽了轴比带宽,提高了低仰角不圆度指标。     

一种宽频带微带贴片天线阵设计

本文在微带天线阵列设计中，采用孔径耦合馈电的办法，将辐射贴片层和馈电网络分层设计，可以获得令人满意的阻抗带宽。实测表明阵列相对带宽可达 20%以上，并且这种馈电方式避免了两者共面时由于尺寸限制，馈电网络难于设计的缺点，减小了互耦及交叉极化，是大型微带贴片天线阵列的一种理想结构形式。     

宽带圆极化微带天线的几种实现方法

在简要概述圆极化微带天线工作原理的基础上,重点介绍了目前国内外较为先进的圆极化微带天线实现宽带的多种方法,包括微带贴片天线、缝隙天线,以及采用PBG结构的圆极化天线。这些方法分别采用单点馈电,多点馈电或多元组合实现圆极化,均有效拓展了圆极化天线的阻抗匹配带宽和圆极化轴比带宽。参考一些实例验证了这些方法的可行性,然后展望了其可能的发展趋势。     

Scan performance of infinite arrays of microstrip patch elementsloaded with varactor diodes

The analysis and scanning characteristics of an infinite array of rectangular microstrip patches each loaded with a varactor diode is presented. The analysis is based on full-wave moment method theory and uses attachment modes to accurately model the current through the feed and the diode. The effect of the biased varactor diode on the scan performance is presented, and it is shown that the impedance mismatch caused by a scan blindness can be eliminated. Other characteristics are also given such as: the active element gain, the efficiency of each loaded microstrip element, and the level of cross polarization generated by the loading of the patch. The effect of the diode biasing level as well as the position of the diode on each radiating element on these scan characteristics is also considered     

Multiple-polarization microstrip reflectarray antenna with highefficiency and low cross-polarization

This paper presents the study and prototype demonstration of the concepts of antenna focusing, cross-polarization reduction, and multiple-polarization capability of a planar microstrip reflectarray antenna. A square patch with two equal microstrip delay lines connected to its two orthogonal feeding points is used as the antenna element of the planar reflectarray. The length of the delay lines, which varies from patch to patch, is schematically designed to focus the plane wave to the feed point. The measured overall efficiency of the prototype antenna is above 50% in the normal operating band, and in some frequency ranges the efficiency has reached 70%. The experimental patterns show that the measured cross polarization due to special arrangement of the delay lines is quite low at the direction of the main beam. X-polarization and Y-polarization measured data show that the antenna is suitable for multiple-polarization applications (dual linear and dual circular). Surprisingly, the antenna has achieved approximately greater than 7% of gain bandwidth (-3 dB gain drop). These results demonstrate the feasibility of such an antenna for radar and communication system applications     

Wideband stacked SSFIP patch antenna for SAR applications

A dual-polarised aperture-coupled microstrip stacked patch antenna with stacked feed lines is presented. The antenna is capable of operating over a bandwidth of 30% with improved front-to-back ratio performance. The patches are excited through non-resonating crossed slots. The feed lines are separated by a thin substrate to enhance the port decoupling. The measured impedance and radiation pattern of the antenna at C-band are presented.     

Ka波段圆极化平板阵列天线设计

本文设计了一种规模为 8×8 的 Ka 波段圆极化平板阵列天线。2×2 子阵为一个圆极化基本单元,子阵馈电方波导腔体中插入极化膜片形成圆极化特性,使用全并馈 E 面波导功分网络对 16 个子阵实现等幅同相馈电。设计的阵列天线实现了良好的圆极化特性与高增益特性。     

一种宽轴比带宽L频段圆极化贴片天线

圆极化全向天线由于其自身的性能特点,在现代无线应用中越来越受到广泛的关注。提出一种宽轴比带宽的L频段圆极化微波贴片天线,该天线有上下两个介质层,下层微带馈线耦合馈电,接地面蚀刻十字交叉缝隙以帮助实现圆极化和改善上层贴片的耦合度。设计结果显示,该天线3dB轴比带宽可以达到3．5％（1.0231．060GHz）,在有效带宽内天线增益高于5．68dBi,在中心频率点（1．04GHz）天线的前后瓣比高于20dB。     

Low-cost, high-efficiency quasi-planar array of waveguide-fed circularly polarized microstrip antennas

A low-cost quasiplanar Ku-band array of circularly polarized microstrip antennas benefiting from a low-loss waveguide feed network is demonstrated (patent pending). The 32 elements of the array which are arranged in a 2-by-16 configuration are subdivided into four two-by-four subarrays. To maintain feed losses and thus the overall noise temperature at a minimum, the subarrays are excited using a one-by-four corporate feed network of hollow metallic waveguides. This network is composed of E-plane components such as Tee-junctions and bends and is manufactured out of only two metallic pieces that accommodate the feed network in the form of milled grooves. Because of insensitivity of the exploited E-plane components to air gaps or slight misalignments, the pieces are secured together with only four screws without welding, braising, or conducting adhesives. Owing to a low-loss foam substrate, the array elements show high circular polarization gain of 9 dBic and wide relative bandwidth of 4%. To achieve circular polarization, use is made of circular patches with two nearly perpendicular perturbations. Using sequential rotation of the elements along with quadrature phase shifting, the axial ratio of the array is reduced to 1 dB over 4% of bandwidth. The measured circular polarization gain of the array amounts to 23 dBic with an aperture efficiency of 63% in the Ku-band of frequencies. The achieved efficiency, which is higher than the reported efficiency for comparable planar arrays with microstrip feed networks, can be credited to the low losses of only 0.2 dB in its waveguide corporate feed. The paper also presents measurement results for an arrangement of two inclined single arrays mounted in parallel. This configuration which has a measured circular polarization gain of 25.7 dBic with an axial ratio of 1 dB is desirable for mobile low-profile antenna systems.     

Single-Fed Microstrip Patch Antenna With Switchable Polarization

A single-fed reconfigurable microstrip antenna that can provide various polarization diversities is presented in this paper. The antenna is excited by a microstrip feed line through aperture coupling. When two PIN diodes are used to respectively reconfigure the coupling slot and the open stub of the feed line, the polarization of the microstrip antenna can be switched between vertical and horizontal polarizations. For the reconfigurable antenna with the linear polarization diversity, it can be converted to a circularly-polarized antenna with switchable polarization sense by introducing a perturbation segment. Moreover, an antenna with the quadri-polarization diversity, including dual orthogonal linear polarizations and two circular polarizations, is also developed from the structure of the switchable circular polarization microstrip antenna, and only three diodes are required. Details of the antenna design are shown, and the measured results for the constructed prototype are also exhibited and discussed.     

A Novel Single-Feed Circular Microstrip Antenna With Reconfigurable Polarization Capability

A single-feed circular microstrip antenna with reconfigurable polarization capability is proposed. This antenna has a simple structure, which consists of a radiating circular patch, five switches (PIN diode), three matching stubs, and a 50 microstrip feed line. It can be switched between 4 different states: two states (low-frequency and high-frequency) for linear polarization (LP), one state for left hand circular polarization (LHCP) and one for right hand circular polarization (RHCP) by controlling the bias voltage of two PIN diodes. At the same time, three switchable matching stubs are used for matching every polarization state. Simulation results and experimental results show that the proposed antenna demonstrates a low cross polarization level, good impedance bandwidth, and a very good axial ratio in the circularly polarized states.     

Design of an Efficient X-Band Waveguide-Fed Microstrip Patch Array

The design and fabrication of a 10.5 GHz microstrip patch array fed by a waveguide is presented. The gain of this antenna is 29 dB and its efficiency is 65%. Commonly, the efficiency of conventional microstrip arrays at X-band is not more than 50%. This antenna demonstrates the ability to accomplish a very high efficiency at X-band in a simple structure. This is achieved by using a slotted waveguide to feed the planar array. To allow symmetrical feed of this antenna, the waveguide is a center-fed slotted waveguide, the two ends of which are shorted. The design procedure is expatiated, which contains the study and design of the waveguide-fed subarray structure and of the coax-to- waveguide transition structure. For designing this entire antenna, a three-dimensional electromagnetic field simulation software CST Microwave Studio is applied. Good agreement is achieved between measurement and simulation results.     

A new design of horizontally polarizedand dual-polarized uniplanar conical beam antennas for HIPERLAN

It is shown that a conical beam 5.2-GHz antenna suitable for HIPERLAN application, but working in horizontal polarization, can be realized as a group of microstrip patch radiators in a ring formation. Layouts with three and four patches are described, and radiation patterns are found to agree well with predictions from a simple array model. The three-patch form is smaller and gives a closer approximation to an azimuth-independent pattern. Patterns are very similar to those achieved in vertical polarization with previously reported disk antenna realizations, giving peak radiation at about 50/spl deg/ elevation. Two methods of impedance matching are found to give satisfactory results. A dual-polarized conical-beam microstrip antenna, with a strictly uniplanar conductor pattern, is also presented and realized as an array of three square patches whose corners meet a central feed point. For the second polarization, the antenna functions as a series fed array. Fairly good conical beam patterns have been obtained, though only moderate polarization purity appears to be obtainable from three-element arrays.     

Polarization‐Diversity Cross‐Shaped Patch Antenna for Satellite‐DMB Systems

A small reconfigurable patch antenna is proposed to achieve polarization diversity for digital multimedia broadcasting systems at 2.6 GHz. To obtain polarization diversity, a pair of on‐slit PIN diodes is inserted in each diagonal of a cross‐shaped patch. Thus, four PIN‐diodes on these slits are utilized to change the connection of the slits and thus achieve polarization. Bias circuits for the diodes are allocated in the cutting corner of the cross‐shaped patch to minimize the antenna size. The antenna produces left‐hand circular polarization, right‐hand circular polarization, or linear polarization, depending on the PIN‐diode status. Analysis of circular polarization operation is explicated. Measurements show a gain of about 1.5 dB, a cross polarization of about ?20 dB, and an axial ratio of about 2.5 dB.     

双频段双极化微带天线阵列设计*

设计了一种双频段双极化的阵列天线。该阵列天线采用多层微带天线形式,七层结构,通过口径耦 合和微带线边馈两种馈电方式实现双线极化,在辐射贴片上方增加寄生贴片以扩展带宽,实现双频段。天线工作在 12.25 ~12.75GHz 及14 ~ 14.5GHz,实测增益18dB 左右,隔离度大于40dB。该天线剖面低,重量轻,可作为子阵组 成更大规模的双频段双极化阵列。