Ultra-Wideband Phase Shifters

A method with clear guidelines is presented to design compact planar phase shifters with ultra-wideband (UWB) characteristics. The proposed method exploits broadside coupling between top and bottom elliptical microstrip patches via an elliptical slot located in the mid layer, which forms the ground plane. A theoretical model is used to analyze performance of the proposed devices. The model shows that it is possible to design high-performance UWB phase shifters for the 25deg-48deg range using the proposed structure. The method is used to design 30deg and 45deg phase shifters that have compact size, i.e., 2.5 cm times 2 cm. The simulated and measured results show that the designed phase shifters achieve better than plusmn3deg differential phase stability, less than 1-dB insertion loss, and better than 10-dB return loss across the UWB, i.e., 3.1-10.6 GHz.     

High Power, p-i-n Diode Controlled, Microwave Transmission Phase Shifters

An iterative circuit, diode, transmission phase shifter is discussed, having a canonic form that consists, of a length of transmission line symmetrically loaded at its ends by small susceptances whose values are diode controllable. The spacing of the susceptances is chosen so that their reflections are nearly mutually canceling, (about a quarter wavelength if equal magnitude, opposite sign susceptances are used). A change of electrical length of the section of 23/spl deg/, in principle, is obtainable with a maximum input VSWR of 1.04. Eight section, experimental circuits yielded 180/spl deg/ total phase shift with less than one decibel of loss in the L and S bands and peak RF power capability to 15 kilowatts. Operation to 140 kilowatts peak power was achieved with reduced phase shift per section. The transmission phase shifter is believed to be well suited as a phase control element for beam steering of array antennas.     

Broad-Band Diode Phase Shifters

Design figures are presented for four types of diode phase shifters: switched line, reflection, loaded line, and a new type using lumped-element high-pass and low-pass circuits. Comparison of their bandwidths shows that most of them can work over an octave bandwidth.     

光波-毫米波无线通信技术

就光波 -毫米波无线通信系统的结构、特点、关键技术和最新进展进行了较全面的论述。尤其是对于毫米波信号的产生、光电子器件的选择、光链路的结构及基站的设计等问题进行了较深入的讨论。     

基于MEMS技术的射频移相器

微波与毫米波移相器是通讯和雷达应用上相控阵天线的基本单元，MEMS技术的引入提供了一个在移相器设计中用最小损耗的开关来大量减少移相器插入损耗的方法，该方法可以降低器件的功耗，改善插入损耗、隔离度、频带宽度等性能。相比于GaAs移相器，基于MEMS开关的射频移相器，无论是开关线型、分布式或是反射型，都有很好的RF性能。     

Ku波段锁式铁氧体移相器

我们利用双平板模型推导出了锁式铁氧体移相器的超越方程。根据超越方程和铁氧体的参数对Ｋｕ波段自动跟踪同步通信卫生电视接收系统中的锁式铁氧体移相器进行了数值分析，结果表明：差相移随温度的增加而减小，但随频率的增加而保持不变。     

光纤链路相频特性对光控阵列影响的研究

通过光控相控阵列的数值模型和成对回波理论,理论分析并仿真了光路相频特性的波动及其各子阵光路相频特性波动对光控相控阵阵列方向图与脉冲压缩的影响。结果表明光纤链路相频特性对阵列方向图和脉冲压缩存在一定影响,但是由于阵列叠加作用,这种影响可能被削弱。     

Phase-Shift Characteristics of Helical Phase Shifters

The phase shifters considered consist of a helix surrounded by or surrounding a ferrite toroid. The ferrites work at their maximum remanent magnetization. It is shown that the helix surrounding a ferrite allows at any combination of frequency and helix diameter a larger differential phase shift than the helix surrounded by a ferrite does; and that in the latter helix the phase shift is easily disturbed by the TE/sub 11/ mode. It is furthermore shown that the 3/spl lambda//4 per turn helix offers a larger fractional bandwidth than the /spl lambda//4 per turn helix does unless one uses ferrites with very low saturation magnetization. The theoretical results are supplemented by experimental data.     

Precise Control of Ferrite Phase Shifters

Hysteresis and thermal drifts can prevent accurate calibration of ferrite phase shifters. To provide a precise setting of phase in response to a control signal a servo system has been developed. This system utilizes a control frequency to determine uniquely the phase shift in a ferrite element. The desired phase shift is then a function only of control frequency and line length. Performance data are given for various operating conditions of the control system.     

Diode Phase Shifters for Array Antennas

This paper contains considerations for diode phase shifters used for phased array antenna control. The categories are: 1) areas in which ferrite and diode phase shifters differ, 2) diode phase-shifter circuits, 3) the nature and typical performance of p-i-n diodes, 4) the requirements of a driver and a typical circuit, and 5) measured performance of phase shifters in L, S, C, and X bands.     

Reflective-Type Phase Shifters for Multiple-Antenna Transceivers

A 10.5-GHz reflective-type phase shifter (RTPS) using resonant loads with L-match impedance transformation (RLT) is implemented in a 0.25-mum SiGe BiCMOS process. A 2.4-GHz RTPS with RLT loads is also integrated in 0.18-mum CMOS; it employs a negative resistance (NR) technique to reduce the loss by 5.9 dB compared to a conventional design that is also implemented. Several other 2.4-GHz reflective loads are fabricated in 0.18-mum CMOS including a Y-shaped dual RLT (DRLT). A transformation converts it from a Y-shape to a Delta-shape and enables use of the NR technique in an RTPS with DRLT loads, wherein the loss is reduced by 10 dB and the phase shift range is increased to over 360deg.     

Nonreciprocal Remanence Phase Shifters in Rectangular Waveguide

Three types of nonreciprocal remanent phase shifters in rectangular waveguide are described which are approximated by a simple model consisting of twin ferrite slabs symmetrically placed in rectangular waveguide and separated by a dielectric rib. The model has been analyzed with the assumption that a fundamental TE mode wave propagates in the structure. Simultaneous solution of Maxwell's equations in the three regions of dielectric, ferrite, and air within the waveguide enables the characteristic equation to be formed. The characteristics of the model have been obtained with the aid of a computer as a function of dimensions, dielectric and magnetic constants, frequency, and power. The theoretical results are compared with experimental data obtained on a double toroid structure. Correction factors applied to the experimental data, which are necessary to account for differences between the practical structure and the ideal model, are discussed.     

X波段GaN基小相位移相器设计

基于0.25 μm GaN HEMT工艺,设计并制作了X波段11.25°和22.5°的小相位移相器单片微波集成电路(MMIC),两个移相器单元均采用低通开关滤波型拓扑结构.最终芯片面积分别为0.9 mm× 1.05 mm和0.95 mm× 1.05 mm.芯片测试结果表明,两个小相位移相器性能良好,且测试结果与仿真结果吻合.在8 ～ 12 GHz频带内,11.25°和22.5°移相器电路的相移精度小于2.8°,输入回波损耗分别优于-15和-12 dB,插入损耗值分别小于1和1.5 dB,幅度波动分别小于0.8和1.3 dB.两个移相器电路的1 dB压缩点输入功率均大于36 dBm,其功率容限优于GaAs HEMT设计的移相器.结果表明,所设计的移相器具有优异的相移精度以及良好的功率性能,可广泛应用于高精度和大功率的雷达系统中.     

Ferroelectric Phase Shifters for VHF and UHF

The analysis, construction, and performance of compact surface wave ferroelectric phase shifters suitable for operation in the100-to1000-MC frequency range are described. Although this ferroelectric loaded parallel-plane structure is a very low impedance structure, a satisfactory terminal impedance matching technique has been devised. Kilovolt level voltages are needed; but since the current required to maintain or rapidly shift phase is low, the over-all control power requirements are at least an order of magnitude less than those for comparable ferrite phase shifters. One of these room temperature operable phase shifters provided 348/spl deg/ of phase shift at 207 Mc. It had an insertion loss which varied from 3.7 to 2.2 db over a zero- to 4000-volt range of applied dc control voltage.     

Coplanar Phase Shifters Based on Ferroelectric Thin Films

Barium strontium titanate (Ba_0.6Sr_0.4TiO₃, short for BST) thin films were prepared by RF-magnetron sputtering. The dielectric tunability, loss tangent, remanent polarization (2Pr) and coercive electric field (Ec) of the BST films are respectively 29.5%, 0.013, 2.29 μC/cm² and 22.27 kV/cm at 1 kHz and 20 V. The designed coplanar waveguide (CPW) phase shifter consists of 56 same sections. It is shown that the fabricated lines of electrodes are smooth and the widths at the tip of bottom electrodes are about 5 μm. At the central frequency of 28 GHz and a bias voltage of 20 V, the figure of merit is approximately 13°/dB.     

Resonant Cavities Used as Frequency Selective Phase Shifters

An application of resonant cavities as frequency selective phase shifters in a multicoupler configuration is described.     

BST移相器的优化设计算法

近年来,人们在微波应用领域对BST移相器进行了很多研究。本文对BST铁电移相器电路进行了等效分析,就电路中重要部分-BST电容加载的方法进行研究,创新地提出了BST电容非周期性加载的设计思路。用M atlab编程实现并论证这种设计思路。使用这种优化方法设计出的非周期性加载移相器各项指标均优于周期性加载移相器,现已申请专利(专利号:200510028313.9)。     

Low Cost Design Techniques for Semiconductor Phase Shifters

The design and performance of two microstrip semiconductor phase shifters operating at S band and UHF are described. The S-band diode phase shifter uses thick-film metallization on a 99.5-percent alumina substrate and uses series coupled diodes for the small bits and constant phase frequency switched life bits for the three large bits. The 4-bit UHF phase shifter uses eight p-i-n diodes mounted in a low dielectric constant microstrip circuit and operates at a power level of 8 kW peak, 240 W average, and has an average insertion loss of 0.7 dB. Phase and VSWR distributions on 800 units produced are also given. The characteristics of two new microwave semiconductor switching devices, the field-effect diode (FED) and the resistive gate switch are described. These devices operate with only a voltage change. Design and performance of an SP2T switch and 3-bit phase shifter using the field-effect diode are presented.     

光控相控阵雷达

由于孔径效应和孔径渡越时间的限制,传统的相控阵雷达难以在大扫描角下实现大瞬时带宽。把光纤技术应用于相控阵雷达,主要包括光纤延迟线形成相控阵雷达波束所需的相移、电光相控阵发射机中采用集成光学进行波束形成,用光纤技术进行天线的灵活遥控、利用光纤色散棱镜技术的宽带光纤实时延迟相控阵接收机等,可以在大扫描角下实现大瞬时带宽,在提高雷达的分辨率、识别能力、解决多目标成像、对抗反辐射导弹、简化结构、减小体积、重量、抗恶劣电磁环境、容易维护等方面有巨大的优势。由此形成的光控相控阵雷达目前具有重大的理论意义和实践意义。