Polarisation-agile active patch antenna

A polarisation-agile active antenna has been constructed and tested. The radiation can be selected to be circularly polarised in either sense, or linearly polarised in the vertical, horizontal or either diagonal plane. The antenna consists of two varactor diode loaded active patches using npn bipolar transistors in the common base configuration as sources, and with the patch axes at right angles to each other. The two oscillators are locked to an external source, and the phase from each patch element is controlled by varying the diode bias voltage. By appropriate combination of the phase relationships, the various polarisations are produced.<>     

Broadband circularly polarised crosspatch- loaded square slot antenna

A new design of a circularly polarised square slot antenna loaded with a cross patch is presented. A cross patch inclined diagonally with respect to the square slot is placed at the centre of the square slot. By choosing proper dimensions of the cross patch, two orthogonal resonant modes with a 90deg phase difference for circular polarisation can be excited and feed the square slot antenna using a 50 Omega CPW with a protruded signal strip. 10 dB return loss bandwidth of 846 MHz (39.6%) and 3 dB axial ratio bandwidth of 240 MHz (12.4%) for the proposed antenna are achieved. Gain variation within the CP bandwidth is observed to be less than 1 dB     

Compact design of single-feed circularly polarised microstrip antenna

A compact design of a single-feed circularly polarised (CP) microstrip antenna with relaxed manufacturing tolerances is presented. The CP operation of the microstrip antenna is achieved using a cross slot embedded on the radiating patch. By cutting an additional cross slot on the ground plane, not only the CP operating frequency can be decreased but also the slot-length ratio of the cross slot on the radiating patch can be considerably increased. In addition, the performance of the proposed design, such as CP bandwidth and peak gain, have no significant reduction.     

Singly-fed patch antenna radiating a circularly polarised conical beam

A singly-fed circular patch antenna generates a circularly polarised conical beam with the help of two perturbation elements. The location of the feed point relative to the perturbation elements determines the rotational sense of the circularly polarised wave. Theoretical and experimental results for the radiation pattern and return loss are presented.<>     

A compact microstrip fed dual polarised multiband antenna for IEEE 802.11 a/b/g/n/ac/ax applications

A compact microstrip fed dual polarised multiband monopole antenna for IEEE 802.11 a/b/g/n/ac/ax communication based applications is presented. The antenna is circularly polarised in IEEE 802.11 b/g bands while linearly polarised in IEEE 802.11 a/n/ac/ax bands. The asymmetric U-shaped slot in the ground plane of proposed antenna is used to introduce the necessary 90° phase shift between two orthogonal electric field vectors necessary for circular polarisation. The Ω-shaped slot on patch is used to introduce a band elimination notch between the usable frequency bands. The radiation characteristics of the proposed antenna (at 2.4 GHz) can be changed from left hand circular polarisation (LHCP) to right hand circular polarisation (RHCP) by replacing asymmetric U-shaped slot with its mirror image on the opposite side of ground plane. The proposed antenna has a wide impedance bandwidth of 110.8% and can also be used in various applications including worldwide interoperability for microwave access (WiMAX) and IEEE 802.11p standard based V2V (Vehicle to Vehicle) communication.     

Adjustable axial ratio of single-layer circularly polarised patch antenna for portable RFID reader

A novel single-layer, proximity-fed technique for a slot-coupled circularly polarised square patch antenna operated in the ultra-high frequency band is presented. In the proposed design a pair of radiating square patches with a cross-slot and a microstrip feed line are both etched on the top of a microwave substrate, and a coupling arrowshaped slot is etched on the bottom of this substrate. Simulated and measured results indicate that the proposed structure can achieve circular polarisation operation. Proper adjustment of the feed coupling gap distance between the patch and the feed line results in good impedance matching and circularly polarised radiation, and an impedance bandwidth (VSWR <= 2) of about 3.74% and a 3 dB axial-ratio bandwidth of about 1.62% were obtained.     

Circularly polarised dielectric resonator antenna excited byperturbed annular slot with backing cavity

The circularly polarised dielectric resonator antenna excited by a perturbed annular slot is investigated experimentally. A backing cavity is placed beneath the slot to block undesirable backside radiation. The effects of varying the slot on the return loss and axial ratio are discussed. The radiation patterns and antenna gain of the configuration are also presented     

Circularly polarised conical beam radial line slot antenna

A radial line slot antenna radiating a circularly polarised conical beam is proposed. It is advantageous in the construction of a feeding structure comparing with conventional antennas. Guidelines for the design of the slot arrangement are presented. The experimental results, which are in good agreement with the design, demonstrate the conical beam radiation     

Patch antenna for mobile satellite terminal

A novel microstrip patch antenna suitable for satellite communications is demonstrated. By using two semi-rings or semi-discs, a circularly polarised antenna is constructed. Details of the antenna design together with theoretical and measured results are presented     

Stacked quasi-elliptical patch array with circular polarisation

A simple stacked subarray antenna with circular polarisation is presented. The antenna is based on a quasi-elliptical patch antenna fed with a 45deg offset microstrip line and a circular patch stacked on top of it via an air substrate. The single-element circularly polarised antenna is sequentially rotated into a four-element synchronous subarray resulting in improvement in antenna performance in terms of impedance bandwidth, gain and axial ratio. The antenna is experimentally verified and the results are reported     

Circularly polarised dielectric resonator antenna with metallicstrip

A new design of circularly polarised slot fed dielectric resonator antenna (DRA) is presented. The dissymmetry of the design enabling circular polarisation relies on a metallic strip printed on top of the resonator. Simulations are compared with measurements for a single antenna as well as a four DRA sequential rotation array     

Switchable dual-band circularly polarised patch antenna with singlefeed

A novel patch antenna with switchable slots is proposed for dual-band circularly polarised (CP) operation. Two diode controlled slots are incorporated into the patch for dual-band operation and a pair of tuning stubs are utilised to tune the CP performance. The antenna design and experimental results are presented     

Dual-band circularly polarised microstrip antennas with a singlefeed

The authors present a novel technique for obtaining circularly polarised (CP) dual frequency operation by using two spur-link band-stop filters within the perimeter of a microstrip patch antenna with optimum feed point location and aspect ratio. This circularly polarised dual frequency operation can be obtained without increasing either the size or the thickness of the patch. Furthermore, through several experiments the authors also demonstrate that the location of the feed point establishes and controls a trade-off between axial ratio and impedance bandwidth     

Miniaturised CPW-fed circularly polarised corrugated slot antenna with meander line loaded

A novel CPW-fed circularly polarised antenna with corrugated structure and meander line loaded is presented. This antenna can achieve 44% size reduction compared to the conventional CPW-fed slot antenna. Predicted results are validated by experiment. The measured 3 dB axial ratio bandwidth and the 10 dB return loss bandwidth are 12.4 and 17.1%, respectively. The peak gain of the antenna is 4.0 dBi.     

一种单馈小型化宽波束双层圆极化微带天线

设计出一种单馈小型化宽波束双层圆极化微带天线,通过选取低介电常数的介质基片,在双层圆形贴片上分别刻四个槽减小天线的尺寸,中心开十字缝增加天线的阻抗带宽,在贴片边切角和贴片的对角线上选择合适的馈电位置实现圆极化,天线尺寸减少37%,天线方向图对称性好,波束宽度大于80°,增益大于5.3 dB。     

一种以空气为基板的圆极化微带天线的设计

设计了一种以空气为基板的超高频（UHF）圆极化矩形微带天线。该天线通过在微带贴片四周与中心开槽,减小了天线尺寸,实现天线圆极化的性能。进一步研究了天线的参数对圆极化性能的影响,通过天线参数的优化,使天线达到了良好的圆极化性能。     

Dual-loop slot antenna with simple feed

A dual-loop slot antenna consisting of two identical loops fed by a triplate line is proposed. It is experimentally demonstrated that the antenna radiates a unidirectional beam of linear polarisation. It is also shown that the generation of a circularly polarised wave is possible by adding perturbation elements to the loops.<>     

单馈电双模方形微带天线及圆极化实现收稿

基于展开理论,给出了沿贴片对角线馈电时方形微带天线的内场分布和输入阻抗公式.通过在贴片四周切割缝隙,有效地降低了天线双主模的谐振频率并实现了圆极化辐射,讨论了缝隙长度与天线极化之间的关系.为实现微带天线的小型化提供了一种新途径,给出了UHF波段天线设计实例.     

Application of simulated annealing to design of serial feedsequentially rotated 2×2 antenna array

A 5.8 GHz circularly polarised 2×2 patch antenna array is presented, employing sequential rotation of dual-feed circularly polarised elements; appropriate phase-shifting and power splitting are achieved via a serial feed arrangement. The feed has been optimised using simulated annealing; the resulting structure has a voltage standing wave ratio 2:1 bandwidth of 9.8%. Results obtained by full wave simulation and practical measurement confirm the integrity of the design     

A circularly polarized small-size microstrip antenna with a crossslot

An antenna with a low profile, small size, and a light weight is required in mobile satellite communications. A new, circularly polarized small-size microstrip antenna using a proximity coupled feed method is proposed. A simple configuration based on a cross slot with unequal slot lengths on a circular patch is adopted to realize a small-size element antenna. The proposed antenna has no 90° hybrid coupler for circular polarization. The measured results verify the circular polarization, and the antenna radius was reduced by about 36% by using the slot lengths which are nearly equal to the diameter of the circular patch antenna. Good impedance and axial ratio characteristics have been obtained