Dual polarised microstrip ring antenna with good isolation

Experimental results are presented on dual linearly polarised aperture-coupled microstrip ring antennas operating at 1.8 GHz. The introduction of multiple feeding points has resulted in the achievement isolation between the two ports of 30 dB with cross-polarisation radiation levels of better than 25 dB at boresight relative to the co-polarisation     

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.     

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 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%     

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     

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%     

ALPSS: a millimetre-wave aperture-coupled patch antenna on asubstrate lens

The feasibility of millimetre-wave (MM-wave) aperture-coupled patch antennas, printed at the back surface of substrate-lenses is demonstrated and the corresponding radiation characteristics are investigated. A specific realisation of such an air-lens-patch-slot-strip (ALPSS) antenna on a low-permittivity ϵ _r=4.0 extended hemispherical lens substrate is theoretically and experimentally characterised at 70 GHz. It is demonstrated that the ALPSS antenna exhibits clean, axially symmetric patterns of low cross-polarisation (26 dB), a directivity of 30.4 dB and the 3 dB pattern full-beamwidth remains within 6°-5° between 60-80 GHz. In addition, a very-high front-to-back (F/B) ratio, of the order of 50 dB is measured at 70 GHz, despite the absence of a backing ground-plane. The ALPSS antenna is well suited for low-cost broadband point-to-point communications and collision avoidance applications     

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     

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.     

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.     

Microstrip-fed quasi-Yagi antenna with broadband characteristics

A compact and uniplanar antenna with broadband characteristics is presented. The novel Yagi-like printed dipole array antenna is fed by a microstrip-to-coplanar strip transition, and uses the truncated microstrip ground plane as its reflecting element. An X-band prototype measures a bandwidth of 17%. With 6.5 dB gain, 18 dB front-to-back ratio, and lower than -15 dB cross-polarisation level at 10 GHz     

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     

Design of microstrip-fed series array of dielectric resonatorantennas

An experimental procedure for designing a microstrip-fed series array of dielectric resonator antennas is presented. The procedure was used to design a 10 element array with a Taylor amplitude distribution. A gain of 13.2 dBi was measured at 8.2 GHz with maximum sidelobe levels of -17.5 dB. The cross-polarisation levels were also measured to be quite low, at -20 dB below the peak     

Coplanar waveguide fed quasi-Yagi antenna

A novel coplanar waveguide fed quasi-Yagi antenna is presented. A wide bandwidth is achieved by using a broadband coplanar waveguide to a slotline balun. An X-band prototype has been realised which demonstrates a broad bandwidth (30%), -19 dB front-to-back ratio, and cross-polarisation better than -17 dB at 10 GHz.     

Honeycomb wire antenna

A honeycomb wire antenna is numerically analysed. The radiation in the direction normal to the antenna plane is linearly polarised with a low cross-polarisation component of <-30 dB. The gain is dependent on the interior angles of the radiation cell. The maximum gain for a honey comb antenna of two cells by 17 cells with interior angles of 70° is ~20.5 dB, and the gain drop over a 4% frequency bandwidth is ~2.56 dB     

Suppression of unwanted probe radiation in wideband probe-fedmicrostrip patches

The radiation from the probe feed of a microstrip patch can contribute significantly to the cross-polarisation radiation or to pattern distortion, especially if the patch is fabricated on a relatively thick, low-permittivity substrate. By introducing a second probe, which is fed out of phase with the original probe, this unwanted radiation can effectively be suppressed. To demonstrate this technique, two L-band patches were fabricated, one with and one without the extra probe. The dual probe-fed patch produced more symmetrical radiation patterns and had a reduction in the peak cross-polarisation level of nearly 20 dB. The unwanted radiation is effectively suppressed over a bandwidth of >10%     

Compact broadband planar orthomode transducer

The design and test results of a compact C-band orthomode transducer are presented. The transducer comprises four rectangular probes orthogonally arranged in a circular waveguide, designed to work in the WG13 band. Measurements of the system in the frequency range 4.64 - 7.05 GHz agree very well with simulation results and show a cross-polarisation level below -58 dB, a return loss of about -20 dB, and an insertion loss difference of less than 0.18 dB between the orthogonal polarisation modes across the full waveguide band.     

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     

Restraint of unwanted higher-order modes in wideband trackingcorrugated horn

A mode filter for restraining unwanted higher-order modes in a wideband tracking corrugated horn is proposed and a new restraining principle is introduced. The cross-polarisation peak level of the horn can be reduced by >8.5 dB in the transmitting band by using this mode filter     

Compact ridge waveguide slot antenna array fed by convex waveguide divider

A ridge waveguide longitudinal-slot antenna array with a compact transverse dimension is introduced. To broaden the bandwidth of the array, it is divided into two sub-arrays fed by a novel compact convex waveguide divider. A 16-element uniform linear array at X-band was fabricated and measured to verify the validity of the design. The measured bandwidth of S/sub 11//spl les/-15 dB reaches 14.9% while the measured cross-polarisation level is less than -36 dB over the entire bandwidth.