Wideband patch antenna with low cross-polarisation

A wideband patch antenna with low cross-polarisation is presented. Based on a novel meandering-shaped probe feed, an impedance bandwidth (SWR<2) of 24% has been obtained. The cross-polarisation is less than -20 dB across the operating bandwidth. The antenna has a gain of 9dBi.     

Dual-polarised dielectric resonator antenna with high isolation and low cross-polarisation

A novel, dual-polarised dielectric resonator antenna with high-isolation and low cross-polarisation is presented using a hybrid feeding technique. Port isolation of 35.9 dB and a cross-polarisation level of 234 dB are measured. The impedance bandwidth of return loss less than 210 dB is 440 MHz (7.9%) with a centre frequency of 5.7 GHz. Since its feeding mechanism is symmetric, a symmetric radiation pattern is also achieved. It is suitable for the application of synthesis aperture radar and some wireless systems.     

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     

Wideband dual-polarised microstrip patch antenna

A dual-polarised microstrip antenna capable of achieving a wide bandwidth, a high isolation, low cross-polarisation levels and low backward radiation levels is presented. The H-shaped coupling aperture is used. For wide bandwidth and easy integration with active circuits, it uses the aperture-coupled stacked microstrip square patches. Measured return loss exhibits a bandwidth of over 20.9%, and isolation is better than 36 dB over the bandwidth. Cross-polarisation levels and the front-to-back ratio are better than 22 and 21 dB, respectively     

Axial crosspolarization in reflector antennas due to asymmetric cross-polar feed patterns

The on-axis cross-polarisation of a reflector antenna illuminated by a feeding system with an asymmetric cross-polar radiation pattern is examined. A graph is presented from which the cross-polarisation discrimination (XPD) of the reflector antenna can be simply obtained.     

电波暗室静区性能及设计要点

静区性能是电波暗室综合性能的体现,也是暗室设计的关键.分析了静区性能对试验的影响程度,以此作为确定暗室静区指标和暗室设计的依据,论述了影响静区性能的各种因素以及保证静区性能的设计要点.     

Wideband and high-gain one-patch microstrip antenna coupled withH-shaped aperture

The design, fabrication, and experimental implementation of the one-patch microstrip antenna coupled with an H-shaped aperture are presented. The presented antenna has a wide bandwidth, high gain, and low cross-polarisation levels with only one-patch. The measured bandwidth of this antenna is 56.2% for the voltage standing wave ratio ⩽2.0. The cross-polarisation level is below -18.2 dB at the E-plane and below -25.7 dB at the H-plane. The maximum gain at 2.05 GHz is 10.4 dBi and the 3 dB gain bandwidth with a centre frequency at 2.17 GHz is 24%     

Broadband two-layer shorted patch antenna with lowcross-polarisation

The design and experimental results of a new configuration two-layer shorted square microstrip antenna with low cross-polarisation are described. The antenna has a bandwidth of 11% centred around 1.975GHz with a gain of 8.6 dB, and exhibits better than 13 dB cross-polarisation levels in the H-plane. The computed and measured results of the co-planar configuration of the structure are compared with its new two-layer stacked configuration     

The SSFIP: a global concept for high-performance broadband planarantennas

The SSFIP (strip-slot-foam-inverted patch) antenna presents significant advantages over standard microstrip antennas: very broad bandwidth, high efficiency, low cross-polarisation level, integrated radome, lightweight and rigid construction and low cost. A 16-element array with more than 16 dB gain and 21.1% bandwidth for SWR⩽2 has been realised     

紧缩场静区校准用超宽带天线性能的分析

紧缩场是天线天线罩辐射特性、目标散射特性测试的重要设备,在使用前需要对其静区平面波幅度锥削、幅度波 纹及相位变化等电磁性能参数进行校准。紧缩场的静区性能校准离不开全频段的探头接收天线,校准天线的性能会影响紧缩 场静区电磁参数的校准结果。文中阐述了校准紧缩场静区性能的扫描法原理,利用本单位研制的紧缩场校准系统,在某研究 所的紧缩场环境内,比较了标准增益喇叭天线与超宽带双脊喇叭天线分别作为接收探头的差异。实验证明,设计完成的超宽 带双脊喇叭天线具有驻波低、增益适中、更换方便、频带宽等优点,完全可以替代六个波段标准增益喇叭天线的功能。     

Probe radiation cancellation in wideband probe-fed microstriparrays

The dual probe-fed patch technique, which is used to suppress unwanted probe radiation in wideband probe-fed microstrip patches, is extended for the case of a balanced two-patch sub-array. To demonstrate this technique, two S-band microstrip arrays were fabricated: with and without the balanced two-patch sub-arrays. The balanced array showed a reduction in the cross-polarisation peak level by nearly 10 dB. The unwanted radiation is effectively suppressed (20 dB cross-polarisation isolation) over a bandwidth of greater than 6.3%     

Broadband patch antenna with ring slot coupling

A novel broadband linearly polarised patch antenna design is achieved using an H-shaped patch coupled to a microstrip feed line via a ring slot in the ground plane. The results indicate that a wide impedance bandwidth of 54% (2.3-3.845 GHz) can be achieved, together with a broadband gain of 6.6 dB and low levels of cross-polarisation.     

An array feed approach to compact range reflector design

A novel methodology is presented for the design of array feeds for compact range reflectors. The principal design strategy is to illuminate the rim of a standard, circular-aperture reflector with an array pattern null. This results in a reduction in the level of edge-diffracted fields present in the quiet zone. Since low-frequency performance is improved without dedicating reflector surface area to edge treatment, the potential quiet zone size is maximized. Implementation of the technique requires only a few real-valued array excitation coefficients. It is demonstrated that various quiet zone field performance trade-offs can be made by varying either the excitation coefficients or the array size. The quality of the quiet zone field is compared with that of a uniformly illuminated serrated reflector. The operational bandwidth and the effects of both random and systematic array excitation coefficient errors are evaluated     

基于正交基扩展法的多区声场重放技术研究

近年来,空间多区声场重放(spatial multizone soundfield reproduction)技术逐渐成为声学信号处理领域中的新热点,此技术旨在无须使用物理隔离或耳机的情况下为听众提供个性化的听音环境。本文基于正交基扩展法,模拟2-D多区声场重放系统,探究了该方法中参数设置与声场性能的关系。实验结果表明,在预重放声场为整个区域半径1 m,明暗区半径均为0.3 m,平面波数量为80的情况下,随着频率的增加,重放声场的声能对比度性能变差,亮区重放误差变小。增大亮区或其他区域加权参数,降低暗区加权参数,重放声场的声能对比度下降;增大暗区或其他区域加权参数,降低亮区加权参数,亮区重放误差增加。     

Step-horn antenna with high aperture efficiency and low cross-polarisation

A multi-step horn antenna with rectangular or circular cross-section is presented. The horn has about 90% aperture efficiency and low cross-polarisation level. The theory behind such high aperture efficiency is explained and the radiation and return loss characteristics are shown.     

Cross-polarisation level of reflectarray with gapped ring elements

A reflectarray with variable-size-gapped-ring elements has been designed. It is proposed to reduce the cross-polarisation level of a reflectarray using concentric ring elements. 11 dB reduction of cross-polarisation level can be achieved     

Compact active integrated antenna with transistor oscillator andline impedance transformer

A novel oscillating antenna is realised by integrating a transistor oscillator and a line impedance transformer inside a rectangular opening in a rectangular patch antenna. This active antenna exhibits stable operation and a clean spectrum. The measured copolarisation radiation patterns are not affected by the modification of the patch while the cross-polarisation levels are low     

Compact antenna test range without reflector edge treatment and RF anechoic chamber

There are several types of CATRs (compact antenna test ranges) used in antenna-pattern measurements. An offset reflector is generally used to generate the quiet zone of a CATR. Serrated edges, rolled edges, or R-cards are generally chosen along the reflector's edge to reduce the edge-diffraction field inside the quiet zone of the CATR. In order to reduce stray signals from the environment, a high-quality RF anechoic chamber is required for a CATR. In this paper, a new type of CATR, without either a reflector edge treatment or an RF anechoic chamber, is developed. A commercially available DBS (direct-broadcast satellite) reflector antenna, without edge treatment, is used as the reflector antenna of the CATR to generate the quiet zone of the antenna test range. In order to improve the quiet zone's performance, the fields due to feed spillover, edge diffractions, and other stray signals are gated out by the ITDAMS (impulse time-domain antenna measurement system). The RF interference in the environment can also be reduced by time synchronization and pulse integration of the impulse time-domain antenna measurement system. In order to verify the capabilities of the proposed CATR, three kinds of antennas (a low-directivity horn antenna, a high-directivity 60 cm direct-broadcast satellite reflector antenna, and a 25 cm Ka-band Cassegrain LMDS - local microwave distribution system - antenna) were measured by the proposed CATR. The antenna-pattern results agreed quite well with those of a near-field range and a far-field range.     

Ka 波段紧缩场天线的设计

设计了一个Ka 波段紧缩场天线。馈源设计结合角锥喇叭在反射面边缘照射电平下降快与波纹喇叭波瓣宽度宽的特点,通过给角锥喇叭加扼流套的改进设计来实现对反射面的照射。反射面采用锯齿型边缘来降低边缘的绕射作用,并进一步在无法加工锯齿部位贴附三角形吸波材料来减小绕射对静区特性的影响。暗室内采用平面测量结果表明,Ka 波段紧缩场天线静区特性满足设计指标要求。     

CPW-fed circular slot antenna with slit back-patch for 2.4/5 GHz dual-band operation

A circular slot antenna fed by a coplanar waveguide (CPW) is proposed for dual-band operations. Dual frequency bands that cover the 2.4 GHz (2400-2484 MHz) and 5 GHz (5150-5825 MHz) bands were obtained by embedding a pair of slits in the circular back-patch that is printed on the backside of the substrate and concentric with the circular slot. This design resulted in broadside far-field patterns with low cross-polarisation levels in both frequency bands and a small antenna size of 40/spl times/40 mm with the ground plane regarded as part of the antenna structure.