Rectangular microstrip antenna for circular polarization

Richmond's reaction integral equation method is used to design a rectangular microstrip patch to produce a circular polarization. A rectangular patch with the aspect ratioa = W_{x}/W_{y}, in the range 1.015- 1.02 and corner fed by a microstrip line, produces circular polarization. For substrate with thicknessd = 0.16cm,a = 1.017the nearly square patch gives maximum bandwidth.     

A wider band microstrip antenna for circular polarization

Circular polarization is achieved by separating two degenerate orthogonal modes in an annular ring patch antenna, by using an ear at the outer periphery. The analysis of such a structure is performed by using the generalized transmission line model. It is found theoretically that this structure can be used to generate circular polarization over a wider frequency range than other structures. An annular ring is designed and its performance is evaluated. Good agreement between the theory and the experiment is obtained. It is also found that the axial ratio bandwidth is higher for the TM₁₂ mode than the TM₃₂ mode of operation in an annular ring antenna     

一种圆极化可重构微带天线的设计

对圆弧寄生单元微带天线进行了理论分析,设计了一种圆极化可重构的圆形微带天线。该天线通过电控开关控制圆弧寄生单元的状态,从而实现左、右旋圆极化的转换。并利用仿真软件HFSS13.0对天线的特性进行了仿真验证。结果表明,在天线回波损耗S11<–10 dB时,该天线在频段为2.38~2.51 GHz,3 dB轴比带宽为30 MHz,且最大辐射方向处正交极化差达20 dB以上。天线的整体辐射性能良好,且结构简单易于实现,很容易在低频段匹配到50,能够满足WLAN在2.4 GHz频段的要求。     

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.     

Resonant frequency of circular microstrip antenna covered with dielectric superstrate

A simple design formulation to compute accurate resonant frequencies of circular microstrip antennas covered with dielectric superstrates is proposed. It alleviates the rigorous mathematical analyzes and large computational time of some earlier works. This theory is widely applicable to both high and low dielectric constant superstrates as verified with the experiments and other theoretical models. Of all theories, the present one shows the closest approximation with the measurements revealing average percent error as low as 0.52%. The extension of this formulation to predict the accurate design data for conventional microstrip circular antennas are also verified with different experiments and available improved theories for various sets of antenna parameters.     

X频段介质加载圆极化喇叭天线设计

设计了一款基于全介质极化器的X频段圆极化喇叭天线。该全介质极化器加载在线极化喇叭天线的前端,将线极化波转换为圆极化波,并有效辐射出去。同时,该全介质极化器还将天线的实测增益提高了约2 dB。天线的测试结果与仿真结果吻合较好。该天线在X频段（8~12 GHz）的实测S11均小于-10 dB,实测轴比在X频段内均小于3 dB,表明该圆极化喇叭天线具有宽带高增益特性。并且,该全介质极化器使用3D打印技术制作,具有加工简便、成本低的优点。该天线可应用于雷达、跟踪制导、卫星通信系统等领域。     

A reconfigurable microstrip antenna for switchable polarization

A novel reconfigurable microstrip antenna with switchable polarization sense is proposed. The proposed antenna has a simple structure, consisting of a corner-truncated square radiating patch, four small triangular conductors, and a microstrip line feed. Using independently biased PIN diodes on the patch, it can produce linear polarization, or left- or right-hand circular polarization according to bias voltages. From the measured results, low cross-polarization levels when operated in the linear state and good axial ratios in the circular state are observed.     

Broadband circular disc microstrip antenna

A technique for broadening the bandwidth of the circular disc microstrip radiating element is described. Theory based on a simple circuit model is introduced and comparison with experimental work is shown. From this model, a matching circuit is devised, the resulting element giving a bandwidth of 35% (to a VSWR of 1.5) near 8 GHz. This makes the circular disc element suitable for a wide range of radar and communications antenna systems.     

Modified circular microstrip antenna elements

The addition of radial conducting strips to microstrip disc antenna elements alters the circuit and radiation behaviour. Frequency shift, pattern modification and dual-frequency operation can be obtained by proper selection of the strip parameters.     

Analysis of a circular microstrip disk antenna with a thick dielectric substrate

The problem of a circular microstrip disk excited by a probe is solved using rigorous analysis. The disk is assumed to have zero thickness, and the current on the probe is taken to be uniform. Using vector Hankel transforms the problem is formulated in terms of vector dual-integral equations, from which the unknown current can be solved for. Due to the singular nature of the current distribution arising from probe excitation, the direct application of Galerkin's basis function expansion method gives a slowly convergent result. Therefore the singular part of the current is removed since the singularity is known a priori. The unknown current to be solved for is then regular and tenable to Galerkin's method of analysis. It is shown that this analysis agrees with the single-mode approximation when the dielectric substrate layer is thin, and that it deviates from the single-mode approximation when the substrate layer is thick. Excellent agreement of both the computed real and imaginary parts of the input impedance with experimental data is noted. The radiation patterns and the current distributions on the disk are also-presented.     

Slot-coupled microstrip antenna for broadband circular polarisation

Broadband circular polarisation (CP) operation of single-feed slot-coupled microstrip antennas is achieved using an inclined nonlinear coupling slot. This nonlinear slot, end-loaded with two V slots, significantly broadens the CP bandwidth to about 2.1 times that obtained using a simple inclined coupling slot for CP operation. Details of the antenna design are described, and experimental results of the CP performance are presented     

Slot-coupled microstrip antenna for broadband circular polarisation

A microstrip antenna with broadband circular polarisation (CP) is presented. The proposed microstrip antenna has a circular patch and is excited by a series microstrip-line-feed configuration through the coupling of a ring slot in the ground plane. The broadband operation is achieved by coupling two CP resonant elements, which are due to the circular patch and the ring slot, respectively. A typical prototype using foam material of thickness 5 mm as the antenna substrate is constructed. Measured results show the 3 dB-axial-ratio bandwidth centred at 2500 MHz is more than 10%.     

Two-port dielectric resonator antenna loaded with meta-surface for improving isolation and circular polarization generator

In this communication, a dielectric resonator based dual-port radiator is designed. Loading of meta-surface over the dual-port antenna creates two important features that make it unique to the proposed design: (i) conversion of the linear polarized plane waves into circularly polarized plane wave (ii) improve the isolation between the antenna port by more than 30 dB. Experimental measurement confirms that proposed design is working in the frequency range 5.14–5.55 GHz, and a 3-dB axial ratio is produced from 5.36 to 5.45 GHz. Stable radiation pattern and good value of diversity performance are also achieved in the proposed radiator. All of these characteristics make the developed radiator appropriate for WLAN (5.4 GHz) applications.     

Electric tripole antenna for circular polarization

The feasibility of using the tripole antenna for circular polarization was experimentally investigated. Measured impedance and radiation patterns were in agreement with the predictions from the infinitesimal tripole model. For simultaneous operation in both senses of circular polarization the tripole antenna must be fed by a special separator network, preferably of the nonreciprocal type.     

Wideband dielectric resonator antenna excited by cavity-backed circular aperture with microstrip tuning fork

A wideband dielectric resonator antenna excited by a circular aperture is investigated experimentally. The aperture is coupled by a microstrip feedline with a microstrip fork-like tuning stub. A backing cavity is placed beneath the stub to block undesirable backside radiation. The return loss, field pattern, and antenna gain of the proposed configuration were measured, and the results are compared with those without the backing cavity.     

Modified Wolff model for determination of resonance frequency of dielectric covered circular microstrip patch antenna

A new modified Wolff model (MWM) is proposed to calculate the resonance frequency of the circular covered and uncovered patch. For uncovered patches the calculated frequency using the MWM is within 0.5% of the measured value. For covered patch antennas, the MWM determines resonance frequency to within 1% of the results using from SDA.<>     

A NEW MODIFIED CIRCULAR MICROSTRIP ANTENNA

A new modified circular microstrip antenna with circular polarization is researched in this paper and a new method named for equivalent ellipse is proposed by authors to calculate the patterns, axial ratio and partial power gain. The theoretical results agree well with the experimental data.     

Analysis of cross-slot-coupled circular microstrip antenna

The analysis of a cross-slot-coupled circular microstrip antenna is presented. The approach is based on the reciprocity theorem and the exact Green's functions for the antenna structure. The equivalent circuit of the antenna was obtained. The calculated results for antenna input impedance were compared with the measured data.     

Design of square-ring microstrip antenna for circular polarisation

The design of a square-ring microstrip antenna with circular polarisation (CP) is presented. To compact the antenna size and overcome the high impedance problem, the CP antenna is excited by a coupling strip located inside the square-ring patch. Several prototypes of the square-ring CP antennas with various substrate thickness (0.013-0.09/spl lambda//sub 0/) have been constructed and studied experimentally, and their coupling-strip designs and CP performance are described.     

Low-profile dual-frequency circular microstrip antenna for dual ISMbands

A novel dual-frequency design of a singIe-layer, single-feed circular microstrip antenna for dual ISM bands is demonstrated. Due to the embedding of an offset open-ring slot in a circular patch, a novel dual-frequency operation with its two operating modes centred at about frequencies 2.4 and 5.2 GHz has been obtained. The two operating frequencies have similar broadside radiation patterns and same polarisation planes, and small antenna-gain variation. Details of the antenna design and experimental results for the proposed antenna are presented