Broadband conical microstrip antenna

Conical patch antennas, excited on TE11-mode are studied and their resonance frequencies are computed. These antennas present a broader bandwidth compared to classical microstrip antennas and, furthermore, good impedance matching can be easily obtained.     

Microstrip antenna on a conical surface

A theoretical analysis of microstrip antennas on conical conducting surfaces is presented. The resonant frequency, input impedance, radiation pattern, quality factor, and efficiency are obtained for a general geometry. Numerical results for a patch antenna with a cone angle &thetas;₀=33.88° operating in the fundamental TM₀₁ mode are shown     

Circular microstrip antenna on ferrimagnetic substrate

A theoretical analysis of circular microstrip antenna on a ferrimagnetic substrate predicts significantly reduced resonant radii and improved bandwidth as compared to those of similar antennas built on purely dielectric substrates, when operated in the lower range of UHF. The impedance characteristics, return loss, and radiation pattern studied experimentally for antennas built upon a typical ferrite substrate are found to be in good agreement qualitatively with the theoretical results.     

A conical microstrip antenna with uniform substrate

A novel conical microstrip antenna with uniform substrate is investigated. The far field radiation patterns of wraparound microstrip antennas mounted on such a structure are studied theoretically. Results for a wraparound antenna of half-wavelength in width excited by TM₀₁ are given, which are verified accurate and efficient by the ones of wraparound cylindrical antennas when the cone angle is very small.     

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。     

Circular polarisation design of a single-feedequilateral-triangular microstrip antenna

By inserting a narrow slit at the edge of an equilateral-triangular microstrip patch, circular polarisation (CP) radiation can be obtained using a single probe feed. This CP design is easy to implement. Details of the antenna design are described, and experimental results of the axial ratio and radiation pattern are presented and analysed     

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 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.     

Single-feed slotted equilateral-triangular microstrip antenna forcircular polarization

Novel designs of single-feed equilateral-triangular microstrip antennas for circular polarization (CP) are proposed and studied experimentally. It is demonstrated that by embedding a narrow slot or a cross slot of unequal slot lengths in the triangular patch, circularly polarized radiation of microstrip antennas can easily be achieved using a single probe feed. Furthermore, results show that for the design with a cross slot, the proposed antenna can perform CP radiation with a reduced antenna size at a given frequency (denoted as compact CP operation here); that is, the required antenna size is smaller for the proposed antenna for performing CP radiation as compared to a conventional circularly polarized triangular microstrip antenna at a fixed operating frequency. Details of the proposed CP designs are described, and typical experimental results are presented and discussed     

Bandwidth enhancement for dual-frequency microstrip antenna with conical radiation

A design for dual-frequency microstrip antennas with conical radiation patterns is studied. The dual-frequency operation is achieved by exciting two different resonant modes of the square microstrip patch antenna with four symmetrical shorting walls. Then, a method to enhance the impedance bandwidths of the dual-frequency antenna is proposed, and the experimental results show bandwidths are increased by 19 and 31% at the lower and higher operating frequencies, respectively. Simulation analyses are also performed to support the measured results.     

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     

Circular polarisation diversity with small size microstrip antenna

The circular polarisation diversity with the square patch microstrip antenna was obtained by the implantation of the quadrature hybrid as a microstrip feed line. The small size antenna is achieved by using the aperture coupled structure. The cavity model has been used to design an aperture coupled microstrip antenna (ACMSA) and determine the length of the open microstrip stub line in order to match microstrip antenna. The MATLAB and Advanced Design Software (ADS) have been used for designing and simulating the ACMSA. There is a good agreement between the simulated and the experimental results.     

Square-ring microstrip antenna with a cross strip for compactcircular polarization operation

A novel design of square-ring microstrip antenna with a cross strip for achieving compact circular polarization (CP) operation is proposed and experimentally studied. The cross strip can be placed in the centerlines or diagonals of the square-ring patch. Either design can make its excited fundamental mode patch surface current path much longer than that in a conventional square microstrip antenna with same antenna size. By incorporating a small tuning stub for splitting the fundamental mode into two near-degenerate resonant modes with equal amplitudes and 90° phase-difference compact CP operation for the proposed design can he obtained     

一种宽带圆极化微带天线阵的设计与制作

文章利用天线的等效电路模型,分析了展宽天线阻抗和轴比频带的原理.提出了利用Wilkonson功分移相器结合翻转容性馈电结构来展宽微带天线的阻抗带宽和轴比带宽的方法.设计了工作频率为1.268 GHz、轴比小于3 dB的相对带宽为44.4%、在此频带内驻波比小于1.5的天线单元;并利用这样的天线单元组成四元圆形阵列,制作了天线阵,测试结果为圆极化带宽为23.8%,驻波比小于1.5,增益大于8dB.     

Cross-slot-coupled microstrip antenna and dielectric resonatorantenna for circular polarization

Circular polarization (CP) design of microstrip antennas and dielectric resonator (DR) antennas through a cross slot of unequal slot lengths in the ground plane of a microstrip line is demonstrated. The proposed CP design is achieved by choosing a suitable size of the coupling cross slot, which results in the excitation of two near-degenerate orthogonal modes of near-equal amplitudes and 90° phase difference. This CP design can be applied to both configurations of microstrip antennas and DR antennas and has the advantages of easy fine-tuning and less sensitivity to the manufacturing tolerances, as compared to their respective conventional single-feed CP designs. For the proposed design applied to a low-profile circular disk DR antenna of very high permittivity studied here, a large CP bandwidth, determined from 3-dB axial ratio, as high as 3.91% is also obtained. Details of the proposed antenna designs are described, and experimental results of the CP performance are presented and discussed     

小型化北斗导航圆极化天线研究

结合多种贴片开槽方案,采用正交馈电圆极化激励方式,实现了一款北斗B3(1 268.52±10)MHz频点导航天线的小型化设计。通过电磁仿真软件HFSS对其结构参数进行优化仿真分析,数值结果表明:小型化天线在B3处的顶空增益为3.69 dB,低仰角增益≥-1.5 dB(≤±70°),反射损耗小于-10 dB的带宽为20 MHz,带内轴比≤2 dB。该小型化天线贴片尺寸相比同介电常数基板的同频点未开槽天线缩小72.8%,具有一定的应用前景。     

The transition field on the surface of a slot-excited conical antenna

A previous derivation of the transition field on the surface of a slot-excited conical antenna is corrected, and the new result as well as the tip-diffraction coefficient are checked by a calculation involving only the exact normal-mode series.     

一种双极化的MIMO超宽带方环缝隙天线设计

设计了一种双极化的多输入多输出(MIMO)超宽带方环缝隙天线。该天线有4个天线单元,底层由2个方环微带馈电线构成,用于正交偏振。顶层由2个对称结构的方环构成,用于减少交叉极化。方环之间用矩形切口连接,以增加环缝之间的耦合。测量结果表明,该天线在3~12 GHz内隔离比大于22 d B,相关系数(ECC)在可以接受的范围内。该天线可以应用于MIMO超宽带通信系统中。     

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.