Quarter-Wavelength Coupled Variable Bandstop and Bandpass Filters Using Varactor Modes

A quarter-wavelength coupled bandstop filter rising varactor diodes for the 6-GHz band has been proposed and tested. Frequency giving maximum attenuation varies from 4.4 GHz-7 GHz. A quarter-wavelength coupled variable bandpass filter using varactor diodes for the 4-GHz band is also proposed and tested. The passband width varies from 730 MHz-1.22 GHz. The center frequency of the filter can also be changed.     

Design of Dielectric Grating Antennas for Millimeter-Wave Applications

At theoretical procedure well suited for generating design data on dielectric grating antennas for the millimeter-wave region is presented. The procedure utilizes the effective dielectric constant (EDC) method to determine the phase constant of the leaky modes supported by the antenna structure of finite lateral width. The radiation or leakage constant of these modes is obtained from the relatively simple boundary value problem of dielectric grating antennas of infinite width. For single-beam radiation, the practicably interesting case, the phase and leakage constants completely determine the field distribution in the antenna aperture, from which the directivity gain and radiation pattern are then calculated. The dependence of the antenna characteristics on the dimensions of the radiating structure is presented and discussed for epsilon = 12, the dielectric constant of typical millimeter-wave materials, such as silicon and GaAs.     

Microwave Bandstop Filters Using Novel Artificial Periodic Substrate Electromagnetic Band Gap Structures

Novel microwave and millimeterwave (mm-wave) bandstop filters using artificial periodic substrate electromagnetic bandgap (EBG) are investigated in this paper. Three types of microstrip structures using periodically modified trace width, patterned dielectric substrate, and periodically modified ground plane are treated, respectively. By periodically modifying either the width of the conductor trace, the substrate height, or the dielectric constant of a standard microstrip transmission line, it has been possible to design microwave bandstop filter functions with wide stopband characteristics and reduced size, compared to conventional microwave/RF filter structures. Commercial electronic design automation (EDA) and computational electromagnetic tools such as Agilent's advanced design system (ADS) and CST Microwave Studio are used in the design and simulations of these filter structures. The effects of the physical parameters of the structures on the filter characteristic are studied. The design procedure and simulation results are described and possible applications of these filter structures are discussed in this paper. A particularly wide stopband is achieved by the circuits presented in this paper, which use only a few cell elements. A significant performance improvement of microstrip patch antenna has been observed by implementing one of the presented EBG periodic substrate structures.      

Dielectric Slab Rotman Lens for Microwave/Millimeter-Wave Applications

A new form of a Rotman lens is proposed for microwave/millimeter-wave applications such as a collision-avoidance radar. The proposed lens can be described as a dielectric slab fed by slot lines. The new form is expected to show lower loss and lower mutual coupling than the conventional Rotman lenses fabricated with conducting plates at millimeter-wave frequency. Taking the field distribution inside the dielectric slab into account, the$ TE_0$mode was chosen to excite the dielectric slab lens. The dielectric Rotman lens consists of a dielectric slab, tapered slot structure, and the transitions between the antipodal slots and microstrip lines for subminiature A connectors. The conventional design equations have been modified for use in designing the dielectric slab Rotman lens with a high dielectric material. A prototype was implemented with nine beam ports and nine array ports. Measurements from 10 to 20 GHz show that mutual coupling can be lowered at higher frequency. The obtained efficiency of the dielectric slab lens system is approximately 30%. The efficiency of the lens is comparable to that of the conducting plate lenses even though there is a spillover loss from the dielectric slab.     

Generalized Coupled Dielectric Waveguide and its Variants for Millimeter-Wave Applications

The characteristic equations of hybrid TM and TE modes for a generalized coupled dielectric waveguide are derived using the mode-matching technique. From the characteristic equations of the generalized coupled dieketric waveguide, the phase constant, wave impedance, and field distribution can be evaluated. A variety of single and coupled dielectric waveguides can be obtained by assigning proper parameter values to the generalized coupled dielectric waveguide.     

Benzocyclobutene as Substrate Material for Planar Millimeter-Wave Structures: Dielectric Characterization and Application

The application of benzocyclobutene (BCB) polymer as dielectric substrate material for millimeter-wave microstrip structures is investigated in this paper to face the problem of large losses due to standard dielectrics in the high microwave range. Dielectric properties of BCB are characterized from S-parameter measurements on a conductor-backed coplanar waveguide (CBCPW) using the polymer as substrate material. Excellent features, with a low loss tangent and a stable dielectric constant, are demonstrated within the measurement range from 11 GHz to 65 GHz. As a validation of BCB high frequency performances, the design and experimental characterization of a V-band array on BCB substrate is presented. Measurement results on both matching and radiation characteristics of the millimeter-wave array are discussed.     

Synthesis of Even-Order Equally Terminated Transmission-Line Bandstop Filters

An exact synthesis procedure for the design of even-order equally terminated transmission-line bandstop filters is described. The method is optimum in the sense that it does not introduce redundant unit elements into the network. The final network is obtained in the form of a cascade of unit elements and shunt open-circuited stubs.     

Metallized Dielectric Horn and Waveguide Structures for Millimeter-Wave Oscillator/Mixer Systems

A new method of producing millimeter-wave oscillator/mixers and associated antenna horns has been developed. This uses the technique of metal coating of dielectric body, and hence avoids the expensive and difficult machining of conventional metal cavities. A sensitive self-oscillating mixer has been tested in this structure and shown to be free from the unstable operation associated with surface radiation of unshielded dielectric waveguide. Low epsilon/sub r/ dielectric was used, thus facilitating ease of matching in contrast with the high epsilon/sub r/ necessary with the unshielded guide.     

Computer-Aided Design of Millimeter-Wave E-Plane Filters

A computer-aided design (CAD) algorithm has been developed for a class of E-plane bandpass filters. The analysis portion of the algorithm is based on the residue-calculus technique and a generalized scattering parameter method. It is mathematically exact and numerically very efficient. Filters designed with this method have been fabricated and tested in Ku-band. Good agreement with design has been obtained.     

Dielectric Measurements of Millimeter-Wave Materials

It is no longer necessary to use extrapolated microwave dielectric data when designing millimeter-wave components, devices, and systems. Precision measurements can now be made to generate highly accurate millimeter-wave (5 to 1/2 mm) continuous spectra on complex refractive index, complex dielectric permittivity, and loss tangent for a variety of materials such as common ceramics, semiconductors, crystalline, and glassy materials. The continuous spectra reveal an increase in dielectric loss with increase in frequency in this wavelength range for most materials. Reliable measurements also reveal that the method of preparation of nominally identical specimens can change the dielectric losses by many factors. These broad-band measurements were carried out employing dispersive Fourier transform spectroscopy applied to a modular two-beam polarization interferometer. Data obtained with Fabry-Perot open resonator methods at wavelengths of 5 mm and longer will also be compared.     

A New Dielectric Grating Antenna with Large Leakage Constant for Millimeter-Wave Applications

The leakage properties of a new dielectric grating leaky wave antenna are carefully examined by an approach of combining the multimode network theory with the mode-matching method. A systematic comparison is given for the leaky characteristics of the n?=??1 space harmonic of TM mode polarization between the present antenna and the traditional one. It has been found that the former is not only of lower conductor loss, but also of larger leakage constant than the latter. As a result, the dimension of the antenna could be largely reduced, which is of practical significance for some applications. Extensive numerical results of the radiation characteristics are given to establish useful guidelines for the design of the new grating antenna. Furthermore, special features such as cancellation or resonance effects are high-lighted and discussed. Physical insights for the mathematical findings are also presented.     

On the Analysis and Design of Spurline Bandstop Filters

The parameters of general two-coupled lines and symmetric three-coupled lines in an inhomogeneous medium for the lossless case are obtained. The impedance and chain matrices of spurline bandstop filters are derived. One-section spurline bandstop filters with their stopbands centered near 33 GHz have been designed and tested. There is excellent agreement between the experimental results and those predicted theoretically.     

MEMS毫米波滤波器的设计与制作

开展了一种基于MEMS工艺的毫米波带通滤波器结构设计和工艺实现,该滤波器结构采用高阻硅作为衬底材料的薄膜支撑结构,选用平行耦合滤波器形式,使用HFSS分析软件对该结构进行了模拟仿真。设计了中心频率为35.0GHz、带内损耗为2.2dB、30dB抑制带宽为2.2GHz的MEMS毫米波滤波器。给出了一套能降低毫米波损耗的MEMS毫米波带通滤波器工艺流程方案,并针对该工艺流程方案进行了关键参数的工艺误差仿真,实现了MEMS毫米波滤波器的工艺制作和测试。测试结果表明,获得的毫米波滤波器的测试结果与仿真结果比较接近。     

微波介质陶瓷在介质滤波器上的应用

移动通信用天线滤波器应具有尺寸小，频率稳定，插入损耗低等特点。研究了ＢａＯ－Ｎｄ_２Ｏ_３－ＴｉＯ_２系介质材料的组成对其介电性能的影响，并分析了影响插入损耗的各个因素。在此基础上用掺Ｂｉ_２Ｏ_３的ＢａＯ－Ｎｄ_２Ｏ_３－ＴｉＯ_２系材料作介质试制出天线滤波器，测试了滤波器的性能，测定表明所制造的天线滤波器性能能够满足移动通信机的要求。     

Monolithic Integration of a Dielectric Millimeter-Wave Antenna and Mixer Diode: An Embryonic Millimeter-Wave IC

A monolithic silicon integrated circuit consisting of a mixer diode and an all-dielectric receiving antenna has been built and tested at 85 GHz. Radiation is coupled into the device optically with a coupling loss of 2.7 dB. No external metal structure is required for coupling. The design can be used efficiently at considerably higher frequencies, and can be elaborated into more complex integrated circuits. From measurements of video responsivity the losses of various parts of the device are estimated. A simple theory of conversion efficiency is found to agree well with experiment this theory is then used to predict the performance of improved versions of the device. The conversion efficiency obtained with this demonstration device is low; it is shown, however, that acceptable conversion efficiencies can be obtained with a more advanced diode fabrication technology using epitaxial Si or GaAs. Integrated millimeter-wave receivers of this kind should be suitable for short-path terrestrial communications, in applications where compactness and low cost are required.     

A Note Concerning Modes in Dielectric Waveguide Gratings for Filter Applications

Peng and Oliner, and others have shown that TM-to-TE or TE-to-TM mode conversions occur when a single, lowest order surface wave is incident obliquely onto a wide dielectric grating and that the lowest order converted modes of this sort can cause spurious stopbands which are especially troublesome because they are so close to the desired stopband, In this note it is observed that the spurious response situation is not as bad in the case of a grating cut into a dielectric waveguide (which can be thought of as having two, obliquely incident waves present). In this latter case, the fields have even or odd symmetry which eliminates part of the mode couplings includhrg the lowest order TM-to-TE or TE-to-TM couplings. Experimental and theoretical results indicate that gratings can be made to be free from spurious responses or appreciable radiation over sizeable bands so that they can be useful in at least some kinds of dielectric waveguide filter structures.     

Realization of Elliptic Function Bandstop Filters by Means of a Resonated Prototype

Elliptic function bandstop filter realizability is normally improved by the use of a resonated prototype. It is indicated that if unit element transforms are performed before the bandstop transform is performed, a simpler procedure results, as well as exact realizations for cases of N = 5 or higher.     

毫米波同轴连接器低反射绝缘支撑的设计

绝缘支撑的结构对毫米波同轴连接器的电压驻波比性能有很大影响,介绍了利用介质界面上能量全折射原理设计的绝缘支撑结构,这种绝缘支撑结构可以减少介质界面上的能量反射。毫米波同轴电缆组件的测试结果表明,该绝缘支撑结构可以提高毫米波同轴电缆组件的电压驻波比性能。     

A Simple Method to Enhance Gain and Isolation of MIMO Antennas Simultaneously Based on Metamaterial Structures for Millimeter-Wave Applications

Journal of Infrared, Millimeter, and Terahertz Waves - In this paper, a multiple-input and multiple-output (MIMO) antenna with high gain and high isolation based on the metamaterial concept is...     

Design Tables for a Class of Optimum Microwave Bandstop Filters (Correspondence)

Element value tables for optimum microwave bandstop filters consisting of quarter-wave spaced shunt open-circuited stubs are given. Both the stubs and the connecting unit elements contribute to the attenuation response. The tables give element values for 0.01dB, 0.10 dB, and 0.25 dB ripple Chebyshev designs with up to twenty-three elements, and for bandwidths between 30 percent and 150 percent.