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。     

Prototype antenna elements for the next-generation TDRS enhanced multiple-access array

This paper summarizes a study performed to produce prototype antenna elements for the next-generation enhanced Tracking and Data Relay Satellite Continuation (TDRS-C) multiple-access (MA) S-band phased-array antenna. Compared to the multiple-access antenna on the current class of TORS, the enhanced multiple-access antenna requires elements that achieve greater on-axis gain, simultaneous circular polarization capability, and increased beamwidth. To demonstrate that array elements could be realized meeting these requirements, designs that were successful in simulation were fabricated and tested. These included a helical antenna; a novel short backfire antenna, excited with a circular waveguide (cup waveguide) with integrated polarizer and orthomode transducer (OMT); and a corrugated-horn antenna with integrated polarizer and OMVT. The paper describes the design process for the novel elements, and compares measured and simulated results. It also compares the elements in terms of performance, size, and mass.     

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％。     

Broad-Band Ferrite Rotators Using Quadruply-Ridged Circular Waveguide

It has been shown that the rotation of the plane of polarization of a wave propagating in a magnetized unbounded ferrite medium should be independent of frequency. However this is not the case when a ferrite rod of small diameter is placed within a waveguide. For example, if a ferrite rod one-quarter inch in diameter in a fifteen-sixteenth inch diameter circular waveguide is used, the rotation will change by a factor of four to one over the frequency band from 8000 to 10,000 mc. This variation in rotation is substantially due to the waveguide characteristics, and can be minimized by lowering the cutoff frequency of the waveguide. Various methods of lowering the cutoff of circular waveguide are compared. Data on the broadbanding of the rotation by dielectric loading and also by the use of quadruply-ridged circular waveguide is shown. An experimental study showing the effect of the ridge width and height on the cutoff of the circular waveguide and the frequency dependence of the rotation is discussed.     

Polarization of the electromagnetic field of modes propagating in an open circular ferrite waveguide

An open circular longitudinally magnetized ferrite waveguide is considered. Both the frequency-dependent rotation angle of the polarization plane of the HE ₁₁ mode propagating in a lossless waveguide and the effect of ferrite loss on the field polarization is studied.     

脊波导缝隙圆极化天线的设计*

设计了一种新型脊波导缝隙圆极化天线。在脊波导宽边开并联纵缝,从波导耦合电磁波至其上方的四脊波导圆极化器,实现圆极化辐射。采用脊波导不仅减小了单元尺寸,更改善了天线的带宽性能。重点研究了四脊波导圆极化器对相互垂直的两辐射场分量的影响,优化单元的轴比特性。在提取单元谐振电导的基础上,设计了工作在10GHz 的1×10 圆极化波导缝隙阵列。对天线实物测试得到中心频率处的增益为16.8dB,第一副瓣电平为 25dB,阻抗带宽约为8.5%,相对轴比带宽(AR臆3dB)约为3.2%。     

Nonreciprocal effects in propagation of microwaves along a waveguide structure formed from a ferrite plate and a lattice of resonant elements

When microwaves travel in a waveguide along a structure formed from a ferrite plate and a lattice of resonant elements, nonreciprocal effects are observed at the lattice frequencies after application of a magnetostatic field whose intensity is by order of magnitude lower than the field intensity required for excitation of the ferromagnetic resonance at these frequencies. Nonreciprocal transmission and nonreciprocal splitting of the resonance curve with broadening of the resonance band under the conditions of a strong coupling between the ferrite and the lattice elements are observed. The change of the nonreciprocity sign after shifting the ferrite to the other side of the lattice and after reaching the magnetic-field intensity at which the difference between the frequency of the ferromagnetic resonance and the lattice frequency changes its sign is observed. It is theoretically shown that microwaves in a waveguide with a bianisotropic layer modeling a lattice have elliptic (circular) polarization of the magnetic field with frequency- and space-dependent direction of rotation, which is seen from the features of the nonreciprocal effects observed in experiments.     

Dual-Frequency Dual-Sense Circularly-Polarized Slot Antenna Fed by Microstrip Line

A new design of a dual-frequency dual circularly-polarized slot antenna is presented. The dual-frequency is achieved using a single-layer microstrip-fed configuration coupled to a modified annular-slot antenna. The dual sense circular-polarization is obtained by four unequal linear slots which augment the annular slot. Experimental results show the proposed antenna has good circular polarization characteristics for both right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP). The 10 dB return loss impedance bandwidths for the lower (RHCP) and higher (LHCP) bands are 26.7% and 11.3%, respectively. The 3 dB axial-ratio bandwidths are 6.1% and 6.0% with respect to 1.5 GHz (RHCP) and 2.6 GHz (LHCP), respectively.     

圆波导铁氧体锁式变极化器的阻抗匹配研究

本文对铁氧体环加载圆波导锁式变极化器进行了阻抗匹配研究。从而提出了一种设计铁氧体环加载圆波导变极化器阻抗匹配的方法。推导出了/4阻抗匹配的计算公式,计算得到了阻抗变换器的尺寸,测试了实际样品的匹配性能,实测结果和理论计算吻合得很好。     

Unidirectional magnetooptic polarization converters

Inclination of the bias magnetization in a magnetooptic waveguide yields both nonreciprocal phase shifts and polarization conversion. This enables the design of unidirectional polarization converters, i.e., waveguides that switch between orthogonal polarizations for one direction of light propagation, but keep the polarization state for light propagating in the opposite direction. Simulations of double layer raised strip waveguides show that these constraints can be met with properly adjusted geometries. The results lead to the proposal of a polarization independent integrated optical circulator based on two unidirectional polarization converters between a front and a back polarization splitter     

Simple Broadband Circular Polarizer in Oversized Waveguide

In this paper, a possibility is shown to realize a simple waveguide polarizer producing nearly the same circular polarization over a broad frequency range up to an octave. It is based upon the combination of two smoothly squeezed oversized waveguides with different diameters. The principle is similar to an achromatic lens in optics, where two counteracting lenses with differently sloped wavelength dependencies of the refractive index are combined to compensate the dispersion in the desired wavelength range. Consequently, two different wavelengths of light are brought into focus at the same plane. A waveguide for the transmission of microwaves has a similar frequency dependence of the refractive index resulting in a frequency-dependent phase shift between two propagating waves polarized along the symmetry axes of a waveguide with an elliptical cross section. For this reason, an incident wave with a linear polarization between the axes of symmetry can be only converted into a circularly polarized wave over a limited frequency range. However, the diameter and the shape along two counteracting squeezed waveguides can be adjusted in such a way that the frequency dependence of the resultant phase shift is finally canceled out.     

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.     

一种基于电调移相器的可重构天线

设计并实现了一种基于反射式移相器的极化可重构天线。该天线使用一对交叉摆放的领结型振子作为辐射单元,并在馈电网络中通过两路移相器调整双馈端口间的相位差实现线极化、左旋圆极化和右旋圆极化模式之间的切换。通过加载匹配枝节的方法扩展了反射式移相器的移相范围,提高了移相器的移相精度,降低了天线圆极化模式带内的轴比。所设计天线的中心频率为5.4 GHz,在线极化模式下10 dB 阻抗带宽为990 MHz,在圆极化模式下10 dB 阻抗带宽分别为760 MHz 和850 MHz,3 dB 轴比带宽分别为510 MHz和480 MHz。该天线在频带内具有稳定的波束方向图,其平均增益为5.3 dB,并且具有27 dB 的主极化-交叉极化隔离。最终的实测结果与仿真结果基本一致,表明该天线具有良好的性能。     

圆波导介质加载锁式铁氧体变极化器的实验研究

在实验基础上,本文给出圆波导锁式铁氧体变极化器的介质加载的研究结果．实验表明,在铁氧体环内适当加载介质,可明显提高器件的相移,而对插入损耗特性影响甚微．这一发现对改进器件性能,具有极大的实用价值     

Circularly-Polarized Phase Shifter for Use in Phased Array Antennas

An X-band, circularly-polarized, nonreciprocal, ferrite phase shifter has been developed whose size and electrical performance are favorably suited for use in transmission or reflection-type phased arrays requiring element center-to-center spacings of about 0.5 /spl lambda/. The phase shifter has the same configuration as a Faraday rotator with a ferrite rod located at the center of a circular waveguide with an axially applied field. If a circularly polarized wave is passed through this geometry, a nonreciprocal phase-current characteristic is obtained. The array antenna is configured so that no phase-control field reversals are needed between transmit and receive modes of RADAR operation. The radiating element has been designed as an integral part of the beam steering element using waveguide array simulator techniques, this paper will discuss various design problems and performance of the beam steering element. A 1300-element phased array was constructed and tested. Its performance, as it relates to the phase-setting accuracy of 1300 phase-shifter constituents, is stated briefly.     

Dual-band polarization and frequency reconfigurable antenna using double layer metasurface

In this paper, a polarization and frequency reconfigurable antenna with double layer metasurface, responsible for frequency and polarization reconfiguration respectively, is proposed. This antenna could operate in linear polarization in 4 GHz and circular polarization in 5 GHz band. By rotating the frequency reconfiguration metasurface, the linear polarization (LP) operating frequency can be continuously changed from 4 GHz to 4.35 GHz (8.4%) with circular polarization operating frequency around 5 GHz unchanged. Moreover, polarization of the whole antenna at 5 GHz can be reconfigured to linear polarization (LP), right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) by rotating polarization reconfiguration metasurface, the 3 dB axial ratio bandwidth is 5.0–5.2 GHz (4%). In all states, gain of the antenna achieves 5 dBi.     

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。     

Broadband Ferrite Microwave Isolator

A new type broadband unidirectional transmission line has been built utilizing the difference in energy distribution between two counter-rotating circularly polarized waves in a circular waveguide containing a ferrite. This principle of isolation is different from those which have been used previously. A large difference is observed in the energy distribution of two counter-rotating TE/sub 11/ modes in a ferrite loaded circular waveguide. A ferrite rod magnetized along its axis presents an effective rf permeability of approximately two for the mode rotating in a negative screw sense with respect to the direction of magnetization. For the positive sense of rotation the effective rf permeability becomes very small and negligible energy is transmitted through the ferrite rod.     

Analysis of polarization independent Mach-Zehnder-type integratedoptical isolator

This paper proposes, for the first time, an integrated optical isolator independent of light polarization. A Mach-Zehnder interferometer (MZI) with two nonreciprocal phase shifters, one for transverse electric (TE) modes and another one for transverse magnetic (TM) modes can be adjusted so that it blocks the fundamental modes of the waveguides constituting the interferometer propagating in one direction and is transparent for the modes propagating in the opposite direction. If the interferometer branch waveguides are in single mode regime, the performance of the device will not depend on the polarization of incoming light. The nonreciprocal phase shifters can be realized on structures with magnetization tangential to the propagation direction. Three geometries of nonreciprocal phase shifters are discussed and tolerances are estimated     

Combined-Phase-Shift Waveguide Polarizer

A waveguide polarizer exploiting two different phase shift phenomena is presented in this letter. Iris-type discontinuities are in fact introduced in a waveguide structure having different propagation constants for the two principal polarizations. In this way, the required 90 $^circ$ differential phase shift is obtained combining the iris phase shift with the waveguide one. Several operative conditions arise from the combination of the two contributions. This approach has been used to design a broadband waveguide polarizer for the $C$-band antenna feed system of the Sardinia Radio Telescope with ${-}$ 40 dB reflection coefficients and a ${-}$35 dB cross polarization level in a 30% bandwidth.