Offset Cross-Slot-Coupled Dielectric Resonator Antenna for Circular Polarization

A cross-slot-coupled cylindrical dielectric resonator antenna (DRA) is studied theoretically and experimentally. In previous papers, a cross-slot of unequal slot lengths was centered under the dielectric resonator (DR), resulting in circular polarized operation of the antenna. In the present study, the design is enhanced by setting the centers of the two slots at different positions and taking into consideration the partial independence of the slot modes from the DRA mode. Thus, circular polarization (CP) bandwidth of up to 4.7% is attained experimentally in the broadside direction. It is also shown that a largely asymmetrical structure results in a very high bandwidth, but with the tradeoff of distorted CP operation off-broadside.     

A Broad-Band Dual-Mode Circular Waveguide Transducer

This paper describes a broad-band dual-mode waveguide transducer designed to couple two orthogonal TE/sub 11/ circular waveguide modes in separate rectangular waveguide ports. A compact, rugged, and economical junction has been developed to operate from 8600 mc to 9600 mc with a vswr of less than 1.15 at the rectangular port and a mode isolation of 50 db or greater. Developmental models are described to indicate the evolution from theory to the final model. Some problems encountered in attaining a small physical size are discussed in detail. The new junction has application to mode multiflexing, circular waveguide ferrite devices, circular polarization, and as a circular wave guide magic-T.     

基于斜极化法的电光聚合物光波导偏振转换器

采用斜极化法研制了电光聚合物光波导偏振转换器,分析并设计了器件的4 5°斜角电极化结构,并基于DR1/PMMA电光聚合物材料,对器件进行了制作.所研制的偏振转换器,由TE模到TM模和由TM模到TE模的偏振模转换效率分别约为93.6 %和95 .1% ,偏振转换周期电压约为380 V.并讨论了器件性能进一步提高的可能性与方法     

一种宽带高性能可变极化跟踪器

变极化跟踪装置是动中通卫星通信天线系统关键设备之一。采用阶梯形脊和对称转门结正交模式转换结构设计了一种用于极化跟踪天线的快捷可变极化宽带高性能极化跟踪器,实现了射频信号两个正交极化分量的实时跟踪、分离和提取功能。电磁仿真和优化结果表明,设计的极化跟踪器具有宽频带和高极化隔离性能,在Ku频段大于2 GHz频带内,极化隔离度优于-34.7 d B,端口反射损耗≤-22 d B。     

基于斜极化法的电光聚合物光波导偏振转换器

采用斜极化法研制了电光聚合物光波导偏振转换器,分析并设计了器件的45°斜角电极化结构,并基于DR1/PMMA电光聚合物材料,对器件进行了制作.所研制的偏振转换器,由TE模到TM模和由TM模到TE模的偏振模转换效率分别约为93.6%和95.1%,偏振转换周期电压约为380V.并讨论了器件性能进一步提高的可能性与方法.     

Phase Shift by Periodic Loading of Waveguide and Its Application to Broad-Band Circular Polarization

A rectangular or square waveguide may be loaded periodically by thin capacitive or inductive irises in order to produce phase delay or phase advance, respectively. The amount of phase shift may be calculated with accuracy by making use of available theoretical values of iris susceptance and of transmission line theory. The phase shifting sections maybe designed for low voltage standing-wave ratio (vswr) over a considerable bandwidth. When a square waveguide capable of supporting two fundamental modes is loaded periodically, the irises act inductively for one mode and capacitively for the other, thus introducing a differential phase shift. This differential phase shift may be made equal to 90°, in order to convert linear to circular polarization. Furthermore such a device may be made, by proper choice of parameters, to yield near-circular polarization over a bandwidth of 1.65:1, because the variation in phase delay for one mode and phase advance for the other tend to compensate each other as the frequency is varied. Several of these circular polarizers have been built and tested at X band and the measured results of ellipticity and vswr, as well as broad-band performance check with theoretical values quite closely.     

Circular Polarization Dielectric Resonator Antenna Excited by Single Loop Feed

A new feeding method for the circular polarization (CP) dielectric resonator antenna (DRA) is proposed in this letter. Two orthogonal modes (TE^x_δ11, TE^y_1δ1,) of the rectangular DRA are excited by a 90° phase difference of the differential and common modes currents of the proposed feeding structure. To demonstrate the good CP performance of the proposed method, a right‐hand CP DRA for a global positioning system was designed. The impedance bandwidth of the proposed antenna for S₁₁相似文献   

A Simple Artificial Anisotropic Dielectric Medium

The anisotropic properties of an infinite stack of thin dielectric sheets separated by another set of thin sheets with a different dielectric constant is investigated. It is shown that the anisotropic properties are brought about because of the two distinct modes of propagation which can exist in such a stacked array of sheets. The limiting forms of the wave solutions and second-order results for the equivalent dielectric constants are given.     

宽带圆极化微带天线的几种实现方法

在简要概述圆极化微带天线工作原理的基础上,重点介绍了目前国内外较为先进的圆极化微带天线实现宽带的多种方法,包括微带贴片天线、缝隙天线,以及采用PBG结构的圆极化天线。这些方法分别采用单点馈电,多点馈电或多元组合实现圆极化,均有效拓展了圆极化天线的阻抗匹配带宽和圆极化轴比带宽。参考一些实例验证了这些方法的可行性,然后展望了其可能的发展趋势。     

A Miniature High-Q Bandpass Filter Employing Dielectric Resonators

The miniaturization of high-Q resonant microwave structures is of great importance. This must he done to keep pace with the size reduction of other related components. The need has led to an investigation into the feasibility of using dielectric materials as microwave resonators. This paper deals with the application of the TiO/sub 2/ dielectric resonator in a narrowband bandpass filter operating in the 2200 to 2300 MHz telemetry band. The study confirms the theory that a bandpass filter employing dielectric resonators is practical to build, is compact, and will approach the performance of an equivalent waveguide filter. The design employed five resonators mounted in a cylindrical tube that was 1.4 inches in diameter by 4.3 inches long and weighed 4.6 ounces. An equivalent waveguide filter would be approximately 2.3x4.5x16 inches long and would weigh approximately 64 ounces (WR-430). The thermal sensitivity of the dielectric resonator employing TiO/sub 2/ is an inherent problem and oven regulation for narrowband applications will be required. Small, inexpensive thermal jackets are available that will control the filter stability to a value equal to, or better than, that obtained with a filter utilizing aluminum cavities operating in a typical uncontrolled temperature environment.     

Design of Broad-Band Dielectric Waveguide 3-dB Couplers

It is shown how 3-dB couplers with bandwidths on the order of 30 percent can be designed by appropriately taking advantage of the dispersion and the frequency dependence of coupling per unit length between two dielectic waveguides with asymmetrical cross sections. Theoretical methods for computing frequency responses of such couplers are discussed. It is shown how the phase response can be simply compensated to give approximately symmetrical-coupler-type or "magic tee" coupler-type phase-difference responses over comparable bandwidths. Experimental results confirming theoretical calculations are presented.     

宽频带正交极化变换传输阵的设计

传输阵包含接收阵面和再辐射阵面,各由周期排列的单元组成,两个阵面被公共接地板隔开,经由过孔销钉或槽缝相耦合。接收阵面接收发自馈源的球面波,经校正相位并传向再辐射阵面以实现前向辐射。文中提出了两种宽频带正交极化变换的传输阵单元:直接耦合角馈层叠式贴片和近轴耦合U型缝贴片,分别组成相同的接收阵面和再辐射阵面,根据宽频带阻抗匹配的要求,对这两种单元进行了优化设计。然后,采用延迟线实现相位调节,分别设计了37和21个单元的正交线极化变换传输阵,对样品整体仿真结果显示了它们的宽频带、高增益和低交叉极化电平的优良性能。     

基于半解析谱元法的各向异性介质PBG结构传输特性的研究

将精细积分方法与谱单元法结合,对含有各向异性介质的波导介质层光子带隙(PBG)结构的传输特性进行了研究.从矢量波动方程相对应的单变量变分形式出发,对含有各向异性介质波导横截面采用谱单元进行离散,引入对偶变量,将单变量变分原理导入到哈密顿体系,利用精细积分法求出出口刚度矩阵.数值算例将半解析谱元法与常规有限元法、半解析有限元法进行了比较,表明本文方法具有高精度、高效率的特点,而且计算精度随着谱单元阶数的增加呈指数增长.     

新型宽波束圆极化天线--微带介质天线

通过在微带天线中引入介质天线原理,提出了一种以简单方式展宽微带天线波束和提高低仰角增益的新方法,从而发明了一种新型宽波束天线－微带介质天线。该天线具有极宽的波束、较高的低仰角增益和波束范围内有较好的圆极化性能等特点。文中给出了天线的原理、设计公式和实验结果。     

一种双频段圆极化阵列天线

文章将宽带单极化Vivaldi天线正交排列,通过圆极化电桥馈电,构建双频段圆极化阵列天线的基本辐射单元。利用遗传算法优化圆极化基本辐射单元的曲线特性、开槽宽度等影响电性能的主要结构参数,使其阻抗带宽及轴比带宽满足双频段工作的特性。根据相控阵天线理论,将基本辐射单元按矩形栅格排布得到圆极化阵列天线。仿真结果显示该圆极化天线在双频段内满足轴比及波束覆盖要求。该圆极化阵列天线对双频段圆极化阵天线的设计具有很好的指导意义。     

一种RFID小型圆极化四臂螺旋天线

设计了一种用于UHF频段射频识别系统的小型右手圆极化四臂螺旋天线。天线由印制在微带介质板的4个长条形臂组成,通过微带功分器馈电。天线在进行4个端口的单独匹配和功分器相连时,需采用一种新的匹配方法。通过仿真优化,天线尺寸为60 mm×60 mm×6 mm,峰值增益为3.8 dB,带内轴比＜3 dB,3 dB波束宽度＞120°,前后比＞15 dB。实物测试结果与仿真结果吻合。     

部分填充电各向异性介质波导的直线法

文本引用直线法,分析了一般的部分填充电各向异性介质的波导的色散特性。波动方程仅在一个方向上进行离散化,这样就产生了微分——差分方程,可以解析求解。并推导出了一般的色散特性方程。最后,为了证实本方法的有效性,对各向同性介质波导进行了计算并与精确解进行了比较,结果极为一致。同时,对部分填充电各向异性介质波导进行了计算。     

Broad-Band Analysis of a Coaxial Discontinuity Used for Dielectric Measurements

A coaxial line terminated by a gap is considered, the gap being filled with an unknown material. This cell enables measurements of complex permittivity of dielectric materials to be made. The relationship linking the measured admittance to the dielectric properties is obtained from a theoretical analysis of the electromagnetic field in the tine. The equivalent-circuit parameters of a coaxial line terminated by a gap are obtained all higher order waves excited at the discontinuity are taken into account. The measurements show good agreement between measured and calculated data from dc to 12.4 GHz.     

A Simple Artificial Anisotropic Dielectric Medium (Correction)

Robert E. Collin, author of "A Simple Artificial Anisotropic Dielectric Medium", which appeared on pages 206-209 of the April, 1958 issue of these Transactions, wishes to make the following correction to his paper.     

Anisotropic Properties of Strip-Type Artificial Dielectric

Theoretical formulas for the propagation phase constant of a two-dimensional strip medium are presented for general directions of propagation. In addition a number of experimental results are included that verify the validity of the theory. Some of the difficulties encountered in defining equivalent dielectric constants for this medium are also pointed out.