Polarizer requirements for fiber gyroscopes with high-birefringence fiber and broad-band sources

Polarizer requirements for fiber-optic gyroscopes with high-birefringence fiber and broad-band sources are investigated theoretically by employing a model with a single coupling center between polarization modes. The phase bias offset due to a finite polarizer extinction ratio is greatly reduced by incoherent effects, and may be further reduced by using a depolarized source or by appropriate orientation of the polarizer transmission axis. Some experimental data is presented which supports the theoretical model.     

波纹波导极化器的分析

极化器是天线馈电系统中的重要器件,但传统的极化器带宽一般很窄。介绍了一种新型的宽带极化器(波纹波导极化器),其结构是在方波导的两壁加载横槽波纹,使波导中的2个正交模产生了90°的相位差。因而将线极化信号转化成圆极化信号。波纹波导极化器在超过30%的带宽内仍然有很好的相移特性,因此他在宽带反射面天线馈电系统中有着很广阔的应用。     

K波段低轴比的隔板式极化器

展示了一种K波段低轴比的隔板式圆极化器的设计、加工和测试过程。该极化器左、右旋输入端口为WR42标准矩形波导,通过T 型节过渡到极化器方波导主体。设计了盖板式机械结构,降低了极化器的加工和装配难度,同时保证了隔板与波导腔体间贴合的紧密性。给出了不同加工精度对极化器性能影响的评估。最终的实测结果表明,极化器在工作频带内具有良好的端口反射系数与隔离度。在20～24 GHz 频带内所激励圆极化信号轴比约为0.3 dB,可作为高频低轴比极化器研制的参考。     

8-18GHz介质板极化器的分析与设计

介质板极化器在天线设计中的应用非常广泛。从介质板波导形成圆极化波的原理出发,推导出差相移与波导传播常数的关系式。因此只需利用数值方法计算波导的传播常数,从而减小了仿真计算量。分析表明在818GHz超宽带范围内,方波导中插入介质板的圆极化轴比理论上只能达到2．03dB。文中提出介质板插入结合波导口径变形的方法使圆极化轴比小于1．53dB,驻波比小于1．23。对介质板波导的关键参数进行误差分析,得到加工误差对圆极化性能的影响小于2．5％。     

Asymmetric Fission Transmission of Linear-to-Circular Polarization Converter Using Bi-layer Split Ring Structure

A circular polarizer based on bi-layer split ring structure is proposed that could achieve asymmetric fission transmission of linearly polarized wave at the dual band. Firstly, a new approach of “Fission Transmission of Electromagnetic (FTEM) waves” is introduced to understand the polarization transformation behavior for linear-to-circular polarization. The designed structure achieves broadband circularly polarized wave with an asymmetric transmission over resonance frequencies by the principle of FTEM wave. The electronics circuit of proposed structure demonstrates the transformation behavior of EM waves when the electric and magnetic coupling between the upper and lower patterned SRR is reached at the certain strength. The physics of the giant circular dichroism effect and optical activity is illustrated by the surface currents distribution on the structure. The proposed structure achieves a right-handed circularly polarized wave and left hand circularly polarized wave with high transmission at 13.94–15.70 GHz and at 16.0–17.03 GHz, respectively. The axial ratio bandwidth of 11.76 and 6.86% is obtained at the dual band. The simulated and measured results exhibit good correspondence.     

栅条型圆极化器性能的分析

本文采用散射矩阵级联的方法，分析了多层周期性金属栅条构成的圆极化器的极化性能，每一层栅条关于Ｆｌｏｑｕｅｔ模的散射矩阵由采用全域基函数的Ｇａｌｅｒｋｉｎ方法求得。圆极化轴比和驻波比的本文计算值与实验值吻合较好，证实了本文分析方法的有效性。     

一种圆极化透镜天线

提出了一款宽频带高增益的圆极化毫米波天线.该天线由一个半球形的介质透镜圆顶以及一个圆柱形极化器结合而成,将传统的扩展半球介质透镜与介质极化器融合在一起,既能将线极化波转化成圆极化波（反之亦然）,又能有效提高天线的增益.该设计与传统的级联结构（透镜级联极化器）不同,它能够用一个器件同时实现两个器件的功能,并且能大大减小系统的体积,降低插入损耗,减少生产成本.此外,该天线采用3D打印技术来实现,加工精度高并且容易生产,适合于毫米波天线的应用.经过验证,该天线的阻抗带宽能达到38%,轴比带宽为36%,圆极化增益达到22 dBic.     

A wave polarization converter for circular polarization

A linearly polarized wave may be converted to a circularly polarized wave by means of a panel which provides90degdifference in transmission phase between two crossed linear components. This phase difference is obtained over a wide frequency band by means of thin sheets containing both inductive and capacitive shunt susceptance. Low reflection and near unity axial ratio may be obtained by means of three sheets which are spaced for least reflection. An experimental polarizer has been constructed using three photo-etched sheets and a dielectric honeycomb core. Over a 20 per cent band the axial ratio of the circular polarization is within 1.7 db and the insertion loss is within 0.5 db. Over a 46 per cent band the axial ratio is less than 2.0 db and the insertion loss is less than 1.0 db.     

High‐Performance Dual‐Circularly Polarized Reflector Antenna Feed

This paper presents a high‐performance dual‐circularly polarized feed employing a dielectric‐filled circular waveguide. Novel features are incorporated in the proposed feed, such as a dielectric rod radiator for high gain and good impedance matching; dual quarter‐wave chokes for low axial ratio over wide angles and for low back radiation; an integrated septum polarizer; and two end‐launch‐type coaxial‐to‐waveguide transitions. The proposed feed shows excellent performance at 5.0 GHz to 5.2 GHz.     

宽带式隔板极化器

介绍一种宽频带隔板极化器的设计原理、设计思路及其设计实例。这种极化器具有频带宽、轴比小、圆极化端口隔离度高及体积小的特点。对其功率容量的高频仿真表明他能承受较大功率。他可广泛用于微波馈电网络系统。     

一种用于动中通天线的新型波导极化器

低剖面动中通系统中由于天线形式和空间的限制, 通常需要单独的极化器来进行极化跟踪。提出一 种用于动中通天线的新型波导极化器组件, 用于输出相位相同、功率比可调的两路信号。通过一个同轴式正交模耦 合器(OMT)和一个可旋转的180°介质移相器来实现任意角度的线极化, 采用垂直-水平通道相位一致的OMT 进行极化分离, 保证了要求天线处于45°极化角时垂直-水平通道的幅度误差和相位误差降低到可接受的范围, 从而保证了系统的交叉极化隔离度。     

Wideband reflecting frequency-selective surface polarizer for X-band applications

This paper proposed the design of a broadband linear-to-circular reflecting polarizer for X-band applications. The polarizer is designed with three-arm dipole-shaped unit cells with a full ground plane to get wideband performance. The incident linear polarized wave is converted to a right-handed circularly polarized wave upon reflection from the polarizer. The footprint of the unit cell is 9 × 9 mm, which is printed on a FR-4 substrate. Fabricated prototype is measured for its performances like polarization conversion ratio (PCR), fractional bandwidth, and aperture efficiency. The PCR is about 97%, and the fractional bandwidth is 64% with the aperture efficiency of more than 80%. Polarizer performance is analyzed in transverse electric and transverse magnetic modes, and they are stable up to 40° of various incident angles. The polarizer exhibits the 3-dB axial ratio bandwidth from 8 to 12 GHz, which is suitable for satellite applications.     

Wide-View and Broadband Circular Polarizers for Transflective Liquid Crystal Displays

A simple wide-view and broadband circular polarizer comprising of a linear polarizer and two uniaxial films is proposed to enhance the viewing angle of transflective liquid crystal displays (LCDs). For the transmissive mode, over the entire 90deg viewing cone, the normalized light leakage from two stacked circular polarizers is suppressed to below 1.5times10^-2, and contrast ratio over 10:1 is obtained using a normally black vertically aligned transflective LCD. At the same time, this configuration warrants a broadband operation and reasonably good viewing angle (10:1 contrast ratio is over 40 at all directions) for the reflective mode. The physical mechanisms for achieving broadband operation and wide viewing angle are discussed.     

圆偏振片在ACTFELD中的应用

介绍了提高ＡＣＴＦＥＬＤ对比度的一种新方法，该方法利用在显示面板前添加圆偏振片来减小环境光对对比度的影响。在２８００ｌｘ的环境光照射下，得到了加有圆偏振片的显示区比无圆偏振片的显示区对比度高３３％的结果。     

宽带高性能四脊波导圆极化器设计

在射电望远镜和卫星通信天线中,圆极化器是关键部件之一。传统圆极化器在保证0.75 dB轴比时的相对带宽最多为41%,无法满足日益增长的宽频带应用需求。该文利用四脊波导的宽带特性,通过采用具有不同尺寸的水平脊和垂直脊,使四脊波导两个正交主模的相位常数不同,来实现宽带移相特性,并给出了一种宽带四脊波导圆极化器的设计方法。按照这一方法,设计了一款宽带C波段圆极化器,工作带宽为3.625～7.025 GHz,相对带宽64%。该文还研究了圆极化器主要参数变化对其性能的影响,加工并实测了一个圆极化器样机。实测结果显示出,该圆极化器两个正交极化的反射损耗均小于–21 dB,相差90°±3.8°,相应的轴比小于0.6 dB。测试与仿真结果吻合良好,证明了分析与设计方法的正确性。     

A Nonreciprocal Circular Polarizer

A nonreciprocal circular polarizer has been developed. This ferrite device converts linear polarization propagating in rectangular waveguide into circular polarization propagating in circular waveguide. The sense, right- or left-hand, of the circular polarization is determined by the direction of a longitudinal magnetic field applied to the ferrite. If one sense of circular polarization, e.g., right-hand, is transmitted, then only left-hand circuIar polarization can be received. Performance data indicate good ellipticity with reasonable loss and VSWR for two models of the circular polarizer, and for two devices--a circulator and a nonreciprocal antenna element--based on the polarizer. The antenna element permits one antenna to be used both to transmit and to receive the reflected circularly polarized signals from a target.     

Constructing the phase converters consisting of arbitrary number oftranslucent surfaces

An effective analytical method of synthesis of an artificial anisotropic structure has been developed. At a design frequency, it ensures perfect match and a phase shift given. The structure may be formed by arbitrary number of inductive and capacitive grids. The method has been applied to constructing circular polarizers and twist polarizers. The geometrical parameters of the polarizers were found in the explicit form. Analytical criteria for an estimate of the bandwidth of the devices have been derived. Performance of the polarizers over a frequency band was studied. A circular polarizer has been proposed which consists of both a cascade of two inductive grids and a cascade of two capacitive grids. The polarizer can be used when very high axial ratio is needed. It ensures more than 10% bandwidth for 0.99 axial ratio. Measurements have been presented that prove adequacy of the mathematical model for real inductive and capacitive screens     

Phase error bounds of fiber gyro with polarization-holding fiber

Phase error bounds for a fiber gyro with an imperfect polarizer are calculated assuming a broad-band source and high-birefringence fiber. The phase error and resulting zero-point drift is related to the polarization-holding parameterhof the fiber. Comparison of the theory with recent experimentally observed bias drift is made.     

A New Comb Circular Polarizer Suitable for Millimeter‐Band Application

This letter presents a new polarizer which has a simple comb structure inside a circular waveguide. The electrical performance of the proposed comb polarizer is optimized by a circular waveguide radius and by the physical parameters of the comb plates. This polarizer is suitable for providing good performance in millimeter‐band application because of its simple structure and low fabrication cost. In our experiments the dual‐band comb polarizer designed in band 1(K) and band 2(Ka) showed good electrical performance without any tuning elements.     

高阶圆波导模式圆极化器的研究

提出了一种基于光滑圆波导结构的高阶TEmn模圆极化器.运用耦合波理论和数值计算方法对93 GHz TE5,1模圆极化器进行了研究和设计.设计的圆极化器由过渡段和移相段组成,结构简单,易于实现.在88~98 GHz的频带内,最大轴比低于1.18.空间辐射测试结果证明了这种高阶圆极化器的性能.为高性能的低阶波导模式圆极化器的设计提供重要参考.