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%     

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     

Low cross-polarised patch antenna with single feed

A probe-fed patch antenna that generates low cross-polarised radiated fields is presented. The probe is located in the centre of the patch conductor and a microstrip line within the patch is used to ensure that good impedance matching is achieved. Enhanced radiation performance of the printed antenna is demonstrated by theoretically and experimentally investigating a circularly polarised (CP) version of the probe-fed patch antenna and comparing the results with a conventional probe-fed CP patch. The new radiator has an axial ratio of less than 1.5 dB at broadside and a 3 dB axial ratio beamwidth of close to 200deg     

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     

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     

Proximity-coupled U-slot patch antenna

The design and experimental results of a proximity-coupled U-slot microstrip antenna are presented. The impedance bandwidth (VSWR⩽2) of the antenna is 20%, centred at 4.3 GHz. It has an average gain of 7.5 dBi and a cross-polarisation of about -20 dB. Both gain and radiation patterns were measured across the passband. An essential feature in the design is that a Π-shaped feed line is connected at the end of the usual microstrip line     

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.     

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 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%     

新型光子带隙微带贴片天线

提出一种新型光子带隙(PBG)结构微带贴片天线。在同轴线馈电型微带贴片天线的接地板上蚀刻出新颖PBG结构,通过数值仿真得到有效提高增益的结构。实际制作了PBG结构微带天线,并实测了天线特性参数。数值结果和实验结果进行了比较,取得了较为一致的结果.实测天线增益达8.8dB,比无PBG时提高约3dB,验证了该PBG结构的有效性。     

CPW-fed oscillating microstrip antennas

Operating with a low-cost FET, oscillating CPW-fed microstrip antennas working at ~4 GHz have been presented. Because the design is based on slot or slot loop apertures, no via holes are required, These oscillating antennas are compact, easy to fabricate while providing uniform radiation patterns with cross-polarisation levels below -17 dB. Active integrated power combining arrays or active integrated phased arrays are possible future applications of these radiating elements     

Broad-band cavity-backed and capacitively probe-fed microstrippatch arrays

A hybrid full wave method for the analysis of probe-fed infinite phased arrays of single and stacked microstrip patches, backed by metallic cavities, is applied to investigate the combined utilization of the capacitive probe-feeding technique and the cavity enclosure of microstrip patches. The goal is to obtain broad-band microstrip antennas on thick substrates without the limitations due to the generation of surface waves of the conventional microstrip antennas on infinite substrates. A design procedure for the capacitive coupling is investigated and theoretical results for the active input impedance and radiation characteristics of different wide-band antenna designs are presented     

Comparative study on the mutual coupling between different sized cylindrical dielectric resonators antennas and circular microstrip patch antennas

A systematic comparative study on the mutual coupling (S/sub 21/) between dielectric resonator antennas (DRAs) and microstrip patch antennas is presented. The mutual coupling between two cylindrical probe-fed DRAs is studied for different radius to height (a/L) ratios. It is found that the mutual coupling decreases with the radius to height ratio. Comparison between mutual coupling of probe-fed cylindrical DRAs and circular microstrip patch antennas with different dielectric substrates are also studied. The mutual coupling between DRAs is 2 dB stronger than between microstrip patch antennas when the patch is etched on a dielectric substrate of a dielectric constant close to the permittivity of the DRA. The mutual coupling of the circular patch antennas reduces with the dielectric constant of the substrate.     

Ka-band reflectarray using ring elements

A simple ring structure to realise a Ka-band circularly polarised microstrip reflectarray is presented. With rotation techniques employed to focus the reflected wave at a focal point, a 0.5 m right-hand circularly polarised microstrip reflectarray is developed and tested at 31.75 GHz resulting in 50% aperture efficiency. The cross-polarisation levels measured are 40.7 dB down at broadside, showing the validity of the structure.     

Infinite phased arrays of cavity-backed patches

An analysis of the radiation properties of infinite phased arrays of probe-fed circular microstrip patches backed by circular cavities using a rigorous Green's function/Galerkin's method is presented. The effect of substrate thickness on both scan volume and bandwidth performance is considered. Results are compared to those of infinite arrays of conventional probe-fed circular patch antennas     

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     

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.     

Small microstrip patch antenna

A novel small microstrip patch antenna is presented. The probe-fed circular microstrip patch incorporates a single shorting post which significantly reduces the overall size of the antenna. Experimental and theoretical impedance behaviour and radiation characteristics of the modified patch are given. Very good agreement between experiment and theory was achieved     

Center-fed microstrip patch antenna

A novel feeding scheme for microstrip patch antennas is presented, which consists of a coaxial probe and shorting pin separated by a narrow slot centrally cut at the radiating patch. The impedance and radiation characteristics of a conventional probe-fed microstrip patch antenna and the proposed microstrip patch antenna are experimentally examined and compared. The effects of the slot length on the antenna operation are also discussed.     

Reduced size, dual-polarized microstrip patch antenna for wireless communications

A novel, compact, probe-fed microstrip patch antenna for operation in dual-polarization mode is proposed. The novel design is achieved by etching out a symmetric pattern of crossed slots from the surface of a square probe-fed patch. Reduction in patch size of up to 51% with respect to a traditional dual-polarized square patch operating at the same frequency is obtained. Results show linear polarizations in the +45 and -45/spl deg/ with a high isolation of 38 dB between the two ports. Moreover, the 50-/spl Omega/ feed position can be achieved by moving the feed point along the diagonal of the square patch, leading to ease in fabrication.