Symmetric reflectors with zero depolarisation

The polarisation performance of a symmetric reflector antenna illuminated by an ideal feed is limited by depolarisation introduced by the reflector, even if other sources of cross-polarisation are negligible. It is shown that depolarisation can theoretically be eliminated by the use of anisotropic reflectors.     

Reflected fields from twist reflector in twist reflector scanning antenna configuration

Theory is presented for calculating the variation of cross-polarisation suppression ratio and loss in the desired polarisation of a twist reflector in different scanning planes in a twist-reflector scanning antenna system. Theoretical and experimental results for a W-band twist reflector are described.<>     

Optimisation of cross-polarisation performance for tri-reflectorCATR with spherical main reflector

For a tri-reflector compact antenna test range (CATR) with spherical main reflector and shaped subreflectors, the cross-polarisation performance is optimised, based on the beam-mode expansion method. For optimal designs, physical optics (PO) calculations of the quiet zone fields are presented, and it is shown that a tradeoff has to be made between a low cross-polarisation level and a low amplitude ripple in the quiet zone     

Slot bowtie antenna for dual-frequency operation

A slot bowtie, cut in a conducting plate on a dielectric substrate, is backed by a conducting reflector, where the distance between the bowtie and the reflector is chosen to be small to make a low-profile antenna. The antenna is designed for dual-frequency operation at 2.45 and 5.2 GHz. It is found that operation at 2.45 GHz depends on the length of the bowtie, while operation at 5.2 GHz depends on the location of the feed point. Frequency bandwidths of 4.8 and 6.2% (for a VSWR=2 criterion) are obtained around 2.45 and 5.2 GHz, respectively. The radiation is unidirectional and the cross-polarisation component is small     

Ku band electric models for large deployable mesh reflector antenna

Two scaled mesh reflector electric models have been constructed for the design of a 30 m diameter large deployable antenna. Radiation characteristics of the antennas have been measured and compared with calculated results. The similarities between measured and calculated results are very close. The cross-polarisation level especially is considerably low.<>     

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.     

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     

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     

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     

Small rectangular patch antenna

A novel folded rectangular patch antenna is designed and measured. Compared with a conventional patch antenna with the same surface area, the resonant frequency is reduced by 37%. The cross-polarisation level is ~-20 dB     

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.     

Proximity-coupled stacked circular-disc microstrip antenna withslots

The design and measured results of a proximity-fed stacked circular-disc antenna are described. The antenna has an impedance bandwidth of 26%, centred around 4.2 GHz, a gain of 8 dBi, and -30 dB cross-polarisation. An essential feature of the design is the presence of four linear slots in the bottom patch of the stacked arrangement     

反射面天线馈源喇叭边缘照射电平的分析

反射面天线设计的关键就是通过选择合适的喇叭馈源边缘照射电平以追求天线的高性能（增益,旁瓣电平, 效率等）。本文主要利用实例验证了标准反射面天线馈源喇叭的优选边缘照射电平,分析了赋形反射天线馈源喇叭的优选 边缘照射电平,给出了标准反射面和赋形反射面在设计中各自馈源喇叭的优选边缘照射电平。从而可以在设计工作中对 于不同形式的反射面天线有针对性的设计馈源喇叭的边缘照射电平。     

Microstrip-fed high aspect ratio dielectric resonator antenna with dual-resonance broadband characteristics

A simple and broadband, microstrip-fed high aspect ratio dielectric resonator antenna is presented and fabricated. The broadband characteristic is achieved by merging the resonances of two appropriate modes of the antenna. The measured antenna bandwidth can exceed 16% with dielectric constant of 25. The approach provides stable radiation patterns as well as low cross-polarisation levels over the entire bandwidth.     

Wideband stacked patch antenna fed by meandering probe

A meandering probe fed stacked patch antenna is presented. The stacked patch configuration can greatly enhance the impedance bandwidth. Bandwidth of up to 37% (SWR<1.5) has been achieved. The cross-polarisation is less than -20 dB across the operating bandwidth. The proposed antenna has symmetric co-polar radiation patterns in both E- and H-plane. The antenna has a gain of 9 dBi.     

Spherical array self-mixing oscillator antenna

A spherical array self-mixing oscillator antenna is designed by applying the injection locking technique to the spherical array of Gunn diode mounted waveguide radiators. The beam steering with considerably constant pattern and low cross-polarisation can be accomplished without using the sophisticated phase shifters. This antenna is designed and tested at the frequency of 10 GHz     

Compact omnidirectional band-notch ultra-wideband antenna

A novel ultra-wideband printed monopole antenna with a band-notch characteristic and stable omnidirectional radiation is presented. The antenna design adopts a bevelled square patch as a monopole, a double-feed technique and a microstrip feeder embedded with an inverted U-shaped slot. Good agreement between simulation and experiment shows that the proposed antenna achieves an impedance bandwidth of 3.05-5.15 and 6.02-10.84 GHz for VSWRles2, a stable omnidirectional radiation and a low cross-polarisation level.     

Triple corner reflector antenna and its performance in H-plane

An experimental investigation of a novel corner reflector antenna with improved performance is reported. The corner reflector antenna has been structurally modified by attaching two more reflector elements. The parameters such as the primary corner angle, position, width and angle of the secondary elements have significant effects on the H-plane radiation characteristics of the antenna. Certain symmetric configurations of this triple corner reflector (TCR) antenna provide sharp beams with a gain of the order of 3 dB over that of the conventional corner reflector (CR) antenna     

Beam steerable square loop antenna over hybrid high impedance surface

A novel hybrid high impedance surface is presented and a beam steerable four feed square loop antenna is built on this structure. At a test frequency of 4.7 GHz, the proposed hybrid high impedance surface based square loop antenna is 4.69 mm high and has an impedance bandwidth of 650 MHz and directivity of 8.7 dBi. Compared with the earlier reported steerable square loop antenna the new antenna s performance equates to a thickness reduction of 61, bandwidth enhancement of 150 , a directivity improvement of 2 dBi, a co-polar sidelobe reduction of 11 dB, and a cross-polarisation sidelobe reduction of 5 dB.