Fin-line Pin diode BPSK and QPSK modulators

A low insertion lose fin-line PIN diode phase shifter is presented. 90° and 180° phase shifters are realized respectively. Phase error less than 5° and bandwidth 3 GHz at Ka band are achieved. The insertion loss is better than 0.5dB.The BPSK and QPSK modulators consisting of this phase shifter and fin-line coupler are also given. The circuits and results are given.     

Ka波段的反射型模拟电调移相器设计

为了能对射频信号进行连续相位调制,设计了Ka波段新型小型化的模拟电调移相器,该电路基于90°分支线电桥与并联结构变容二极管实现电路大范围移相,利用四分之一波长微带线实现电路匹配及阻抗变换,通过并联补偿电阻平衡其插入损耗波动,并对其进行了详细分析与探讨。仿真及实测结果表明:该移相器在29~31GHz频段范围内,可获得180°左右的相移量,插入损耗优于6.5dB,插入损耗波动在1dB内,相移误差小于10°。     

Integrated ferroelectric millimeter-wave phase shifters with a periodic structure

Integrated phase shifters with a periodic structure that includes BaSrTiO₃ ferroelectric varactors parallel-and series-connected to the transmission line are investigated theoretically and experimentally. The phase shifters are designed for the frequency range 26–32 GHz. The dispersion characteristics and insertion losses in the transmission line of the phase shifters are analyzed with regard to the dependence of the capacitance and loss tangent of the varactors on control voltage and temperature. It is shown that parasitic amplitude modulation in the phase shifters can be suppressed if the connection scheme of the varactors takes into account the voltage dependence of the their loss tangent. In the phase shifters with series-connected varactors, the temperature dependence of the phase shift is much weaker than in those with parallel-connected varactors.     

同轴插板式相移器数值模拟与实验研究

 根据同轴插板式相移器的基本工作原理,对该相移器进行了数值模拟与优化设计,并重点研究了其结构工艺和相移控制方式。在此基础上研制了一个中心频率为4.1 GHz的相移器模型,并通过矢量网络分析仪进行了实验测量。测量结果表明：在4.0～4.2 GHz的频带范围内,该相移器可实现90°的相移量,相移量化精度为1°,相移精度为±１０°,相移器插损1.5 dB。     

Experiment investigations of millimeter-wave grating spectrometer

The lateral shift of focus diffracted and reflected beam and resolving power, insertion loss of a five channel grating spectrometer for 25 to 100 GHz are experimentally investigated. And some analysis for these results are also given.     

一种高功率微波金属片波导移相器设计与特性分析

设计了一种高功率微波矩形波导移相器,在矩形波导中平行于电场放置金属片,沿波导宽边移动金属片,实现波导内的可变相移。通过优化设计波导和金属片的结构尺寸可实现0~360°相移,通过优化设计金属片过渡匹配结构可实现较低的插损。设计波导内为全金属结构,不存在介质材料,采用真空绝缘可以承受较高的功率传输。设计了中心频率为9.4GHz的金属片波导移相器,移相器最大插损小于0.2dB,功率容量设计达到64 MW。实验测试,移相器最大插损小于0.5dB,相频曲线呈线性关系。     

Design and performance of coplanar waveguide slotline bandpass filter

This paper describes the work involved in designing a coplanar waveguide -slotline bandpass filter. The filter designed to achieve at least -30dB insertion loss (S₂₁)in the stopband (8 to 8.5; 9.3 to 10 GHz) and less than -0.2 dB in the passband (8.75 to 9.05 GHz), with a centre frequency of 8.9 GHz. The filter and transition were fabricated on 1.27 mm thick RT-Duriod 6010.2 substrate and S-parameters were tested using standard SMA connectors with an HP-8510A network analyser.     

Effect of Ag substitution on the electromagnetic property and microwave absorption of LaMnO3

La_1−xAg_xMnO₃ perovskites with different doping Ag-content were prepared by the sol–gel method. The electromagnetic characteristics and microwave loss behavior of these ion-doped rare-earth manganites were studied in the 2–18 GHz frequency range. The microstructure and morphology of the samples were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques. The complex permittivity spectra, the complex permeability spectra and microwave reflection loss were measured by a microwave vector network analyzer system. The XRD patterns show that the crystalline perovskite main phase ABO₃ is formed and impurity phases disappear when calcined at 1100 °C, and Ag metal as an impurity phase appears when excessive Ag⁺ is doped. The SEM image indicates that many of the La_0.85Ag_0.15MnO₃ particles are fiber-like or ellipsoidal. Magnetic loss and dielectric loss coexist and cooperate in microwave attenuation by moderate substitution of Ag⁺ for La³⁺. The microwave absorption property of the La_0.85Ag_0.15MnO₃ sample is enhanced with the bandwidth below −10 dB at about 6 GHz and the peak value of reflection loss is near −25.0 dB at the layer thickness of 2 mm.     

超导微波延迟线及其制冷的研究

采用 YBCO/ La Al O3薄膜制作出 5ns和 1 0 ns超导微波延迟线 ,并以小型斯特林制冷机作冷源 ,给出了延迟线的延迟和插损特性。在 77K,1 GHz、5GHz、1 0 GHz时 5ns延迟线的插损分别为0 .1 2 d B/ ns、0 .55d B/ ns、1 .2 d B/ ns;1 0 ns超导微波延迟线在 2 GHz、4 GHz、6GHz插损分别为 0 .1 9d B/ ns、0 .4 4d B/ ns、0 .63 d B/ ns。描述了器件与制冷的设计、制作过程     

Investigation of a heterodyne receiver with open structure mixer at 324 GHz and 693 GHz

The performance of a submillimeter heterodyne receiver using an HCOOH laser local oscillator and an open structure mixer with a Schottky barrier diode has been optimized for 693 GHz. Working at room temperature a single sideband (SSB) system noise temperature of 7,300 K, a mixer noise temperature of 6,100 K and a conversion loss of 12 dB has been achieved. The same receiver system has been investigated at 324 GHz using an HCOOD laser local oscillator yielding a noise temperature of 3,100 K (SSB), a mixer noise temperature of 2,400 K (SSB) and a conversion loss of 10 dB (SSB). An acousto-optical spectrometer has also been constructed, with 1024 channels and a channel-bandwidth of 250 kHz. The system NEP per channel was 2.5×10^–17 W/Hz^1/2 at 324 GHz and 5.0×10^–17 W/Hz^1/2 at 693 GHz.     

140 GHz带状注弯折波导SU-8工艺与传输特性(英)

对140 GHz 带状注弯折波导的色散特性和耦合阻抗进行了仿真。CST微波工作室的仿真表明该波导在140 GHz时,波导内电磁波的轴向相速度为0.227c,且140 GHz频率附近色散特性平坦。波导的耦合阻抗在140 GHz时为5 左右。CST粒子工作室注波互作用的仿真结果表明该弯折波导在140 GHz处的功率增益为24.6 dB。该弯折波导带状电子注的设计保证了该波导的加工工艺与MEMS微加工工艺兼容。通过SU-8 UV-LIGA工艺实现了对该波导的微型加工。测试结果表明该波导的反射损耗S11与插入损耗S21分别为-28 dB和-1.2 dB。实测的输出功率增益达到23 dB。测试结果和仿真结果的一致性表明该弯折波导设计的合理性,同时也验证了多步SU-8 UV-LIGA工艺可以实现对该波导的高精度加工。     

基于补偿型微带谐振单元的一维光子带隙结构

提出了一种具有光子带隙(PBG)性能的补偿型微带谐振单元(C-CMRC)，通过并联两个开路微带线来补偿CMRC结构在低频通带内因为阻抗不平衡而引起的回波损耗，从而减小插入损耗，并且该C-CMRC谐振结构具有更强的慢波效应和更大的禁带宽度.利用该结构谐振单元的慢波效应，设计具有一维PBG性能的低通滤波器，重复周期仅为0.15λ_g.与普通的0.5λ_g周期的PBG结构相比，大大减小了电路面积.实际设计、制作和测试了CMRC和C-CMRC两种结构，通过两种结构的测试结果 关键词： 补偿型微带谐振单元 慢波 禁带 光子带隙     

Microwave dielectric tangent losses in KDP and DKDP crystals

By adding cubic and quartic phonon anharmonic interactions in the pseudospin lattice coupled mode (PLCM) model for KDP-type crystals and using double-time temperature dependent Green's function method, expressions for soft mode frequency, dielectric constant and dielectric tangent loss are obtained. Using model parameters given by Ganguliet al [9] the dielectric losses are calculated for KDP and DKDP crystals. In the microwave frequency range an increase in frequency (1–35 GHz) is followed by an increase in dielectric tangent loss (1–35) at 98 K and (1–15) × 10⁻² at 333 K for KDP and DKDP crystals respectively. The dielectric tangent loss decreases from 0.052 to 0.042 for KDP crystals with increase in temperature from 130 to 170 K and for DKDP crystals it decreases from 0.0166 to 0.0074 with an increase in temperature from 230–343 K in their paraelectric phases at 10 GHz. This shows Curie-Weiss behavior of the dielectric tangent loss     

Diode grids for electronic beam steering and frequency multiplication

Loading a grid with diodes offers the possibility of two-dimensional control of millimeter waves that is analogous to holography and nonlinear optics. These grids are attractive because they are suitable for monolithic integration with gallium-arsenide Schottky diodes and for high-power operation. Here we present grid designs for electronic beam-steering and harmonic generation. The beam-steering grid is a programmable reflector, where the diode bias controls the phase shift of the reflection. The variation of the phase across the grating sets the direction of the reflected beam. The reflection loss in computer simulations is 3dB at 90GHz. The harmonic-generating grid acts as a nonlinear reactive surface, where the nonlinear capacitance of the diodes produces the harmonic frequencies. Quasioptical filters select the desired harmonic. Computer simulations predict that a 65GHz-to-130GHz doubler would have an output power of 0.56W/cm² and a conversion efficiency of 35%.     

Analysis and design of a new type NRD-guide E-plane Y-junction circulator

A new type of E-plane Y-junction circulator has been developed based on the nonradiative dielectric waveguide (NRD-guide) in Ka- band. First, the circulation principle has been analysed by the theory of polarization wave. The field components in the nonreciprocal Y-junction zone and the conclusion of 60° phase difference between clockwise and counterclockwise rotating polarization modes has been obtained. And then, the resonant frequency of the non-dc biased triangle ferrite sample has also been calculated. This kind of structure is benefit to enlarge the bandwidth of the Y-junction circulator. As an example, we had designed and fabricated a circulator in Ka-band. Its operating frequency is 35. 1GHz, the 1.5dB insertion loss and 20dB isolation bandwidth is about 1. 0GHz.     

The millimeter-wave dielectric properties of Al2O3 after irradiation to moderate neutron fluence

Abstract

Mono- and polycrystalline Al₂O₃ has been irradiated to 3.5· 10¹⁹ f.n/cm², and the increase in dielectric loss has been measured at 28–38 GHz and 144–146 GHz. Step annealing experiments have been performed between 150 °C and 1100 °C. The recovery of dielectric loss has been analyzed aiming at identifying the defect types affecting dielectric loss. A pronounced recovery step observed at 450–550 °C is explained by F-centres with strong electron-lattice coupling which contribute predominantly to dielectric loss at room temperature.     

Investigations of sol–gel-derived highly (100)-oriented Ba0.5Sr0.5TiO3 : MgO composite thin films for phase-shifter applications

Sol–gel deposition of highly oriented Ba_0.5Sr_0.5TiO₃:MgO composite thin films has shown desirable dielectric constant reduction and higher figure of merit for phase-shifter applications. In this multilayer configuration, MgO distributed homogeneously through the Ba_0.5Sr_0.5TiO₃ (BST50) matrix, and it helped in tailoring the dielectric constant and reducing the loss tangent significantly. In the present study, the high-frequency dielectric behavior of the films has been evaluated by fabricating an eight-element coupled microstrip phase shifter and measuring the degree of phase shift and insertion loss as a function of applied voltage at room temperature. An increase in phase-shifter figure of merit (degree of phase shift per dB insertion loss) from 28°/dB for pure BST50 to 71°/dB for a BST50:MgO film (at 14 GHz and 333 kV/cm) has been observed. PACS 77.55.+f; 81.20.Fw; 73.40.-c; 85.50.-n     

Optical phase-based beamformer using MZM SSB modulation combined with crystal polarization optics and a spatial light modulator

The performance of a widely tunable phase-based beamformer for phased array antennas using a new technique to cross-polarized the carrier and the sideband, in order to allow the phase control by means of a spatial light modulator, is experimentally demonstrated. The technique relies on the combination of single sideband amplitude modulation (SSB) using a Mach-Zehnder modulator (MZM) and birefringence (to cross-polarized the carrier and the sideband). The architecture has the potential of controlling multiple independent beams simultaneously. The beamformer feeds an eight elements array showing an insertion loss and a reset speed of around 12 dB and 70 ms, respectively. Far-field antenna patterns between 7.5 GHz and 8.5 GHz for nine elevation angles within a range of ±20° have been measured showing beam steering capability, amplitude distribution weighting as well as multibeam operation.     

Microwave dielectric dispersion in ferroelectric telluric acid ammonium phosphate

The paper presents the results of the investigation of dielectric dispersion in monoclinic telluric acid ammonium phosphate crystal over the frequency range 1 MHz to 77 GHz. It is shown that ferroelectric dispersion of the Debye type along the direction perpendicular to the plane (101) occurs in the frequency range 10⁸ to 10¹¹ Hz and is caused by a single relaxational soft mode. The relaxational soft mode is caused by the flipping motion of protons between two potential minima in a hydrogen bond. The frequency of the flipping proton mode in the paraelectric phase varies according to v_s = 0.94 (T – T_o ) GHz and decreases to 1.75 GHz at T_c = 317.3 K. The relaxational mode gives the main contribution to the high static dielectric permittivity of this crystal which fits the Curie-Weiss law. The results confirm the order-disorder nature of a proper ferroelectric phase transition of second order.     

Electromagnetic wave absorption of polymeric nanocomposites based on ferrite with a spinel and hexagonal crystal structure

We have investigated composites designed for microwave absorption based on magnetic filler, composed of phases within the SrO-Fe₂O₃ system, embedded in a polyphenylene sulfide matrix with a concentration ratio of 80:20 by weight. The formation of the nanosized particles of SrFe₁₂O₁₉ and Fe₃O₄, as the principal magnetic phases was achieved via the co-precipitation of Sr²⁺/Fe³⁺ ions using different molar ratios. The various precursors obtained were calcined between 600 °C and 900 °C in air. The electromagnetic parameters of the composites were measured with a vector network analyzer at 400 MHz to 32 GHz. The results show that with a composite composed of a complex magnetic filler comprising the nanoparticles of two magnetically diverse phases, i.e., a spinel phase as the electromagnetic wave absorber in the lower GHz range and a hexagonal phase operating at a higher GHz range, above 32 GHz, a microwave absorber with an broad absorption range can be prepared.