Showing papers on "Waveguide filter published in 1989"

A novel MMIC active filter with lumped and transversal elements

Abstract: An active filter structure is developed, fabricated, and demonstrated as a monolithic microwave integrated circuit (MMIC). This filter structure makes use of both lumped elements and active transversal elements. The filter uses lumped elements to achieve a basic bandpass filter response, and transversal elements to sharpen the bandpass characteristic. Active elements are included to overcome the high loss of MMIC lumped elements. This miniature MMIC filter has a passband of 9.8-11.1 GHz with 2-dB loss and better than 30-dB rejection 1.1 GHz from either passband edge. >

Two cylindrical obstacles in a rectangular waveguide-resonances and filter applications

Abstract: Two metallic or lossy dielectric cylinders placed in one cross section of a rectangular waveguide are investigated by the orthogonal expansion method. Resonances are shown by frequency responses of the transmission coefficient. They are discussed by patterns of the magnetic field and diagrams of the Poynting vector. Physical explanations of the resonances are given. The structure may be used as a filter element. With two small dielectric posts, a frequency characteristic with two stopbands can be obtained. Center frequencies are tunable by moving the posts. Using one large metallic and one small dielectric post, a tunable passband characteristic can be realized. >

Intelligent alignment of waveguide filters using a machine learning approach

Abstract: The authors investigate the application of a machine learning system to the tuning of waveguide filters. This system uses techniques from pattern recognition and adaptive signal processing. The manual tuning of the waveguide filters is very time consuming and expensive and a skilled operator is required. Here, the machine learning system is adapted in such a way that it can assist an unskilled operator to perform fast and accurate tuning of these filters. The machine learning approach is based on the manipulation of some raw data to extract a set of salient features that have strong significance in the behavior of the filters. These features are derived visually, by comparing the characteristics of a tuned filter to those of a faulty filter with known levels of maladjustments. >

Filter design using in-line triple-mode cavities and novel iris couplings

Abstract: The authors present principles for triple-mode filter designs based on a sidewall-tuned triple-mode cavity and two iris geometries. It is shown that these principles allow optimal filter realizations with a minimum number of triple- and dual-mode cavities. Verification of these principles is obtained by realizing several filter types. Experimental results are provided for elliptic-function filters of fifth, sixth (both in in-line configuration), and seventh order. >

Rigorous design of evanescent-mode E-plane finned waveguide bandpass filters

Abstract: The authors present a new design of compact, low-cost, and low-insertion-loss evanescent-mode waveguide bandpass filters with bilateral metallic E-plane fins. Based on the modal scattering matrix method, the rigorous design takes into account the influences of both the finite fin thickness and the higher-order mode interaction at all discontinuities. Computer-optimized-design data are given for filters with passbands in the X- and the E-band with wide stopbands. The theory is verified by measurements. >

Tunable active chirped‐corrugation waveguide filters

Abstract: A novel tunable semiconductor waveguide reflection filter is proposed and analyzed. The filter is based on spatially selective gain pumping of a chirped‐corrugation waveguide. This active chirped‐corrugation waveguide filter (ACF) is considered for monolithic broadband tuning of semiconductor lasers.

Waveguide bandpass filter having a non-contacting printed circuit filter assembly

Abstract: A waveguide bandpass filter employs a waveguide section and a printed cirt filter assembly having a dielectric substrate positioned in the waveguide between the narrow walls thereof and a row or array of half-wavelength conductive metal plate elements lying in a surface plane of the dielectric substrate that is oriented substantially parallel to narrow walls and orthogonal to broad walls of the waveguide. The half-wavelength conductive metal plate elements, defining a parallel resonant array, are spaced in non-conductive relation from one another and from the broad and narrow walls of the waveguide so as to divide and transform a dominant waveguide propagation mode into a transformed propagation mode that approximates upper and lower microstrip sections interconnected by a metallic conductor. The filter also includes a pair of elongated foam dielectric bodies disposed in the waveguide and mounting therebetween the dielectric substrate and half-wavelength conductive plate elements thereon, and a pair of quarter-wavelength conductive metal plate elements on the dielectric substrate which are conductively connected to outermost ones of the half-wavelength conductive plate elements for defining impedance matching transformers adjacent input and output ends of the waveguide.

Rigorous Field Theory Design of Compact and Lightweight Broadband Diplexers for Satellite Communication Systems

Abstract: A new design of compact, lightweight, broad-band and low-insertion-loss diplexers for satellite conununication systems is introduced utilizing E-plane corrugated and below-cutoff waveguide filters in the septate waveguide sections of E-plane furcated power dividers with asymmetrical transformer heights. The rigorous optimization technique comprises the complete component, including all discontinuities as well as the higher order mode interaction between them. Results are given for a computer optimized design exmnple for a minimum input port return loss of about 22 dB over the transmit (3.7 - 4.3 GHz) and receive (5.83 - 6.5 GHz) frequency band. The theory is verified at a R- 48 waveguide diplexer example which was milled from a solid block.

Ceramic microwave filter having aperture-coupled ceramic resonators with steepened resonance curve

Abstract: A ceramic microwave filter (1) having short-circuiting capacitors C1, C2 for increasing edge steepness. The short-circuiting capacitors C1 and C2 are constructionally integrated into the microwave filter (1).

Distributed feedback guided surface acoustic wave microresonator

Abstract: Surface acoustic wave resonators have been used in a number of applications: high‐Q frequency filtering, very accurate frequency sources, etc. A major disadvantage of conventional resonators is their large dimensions, which makes them inadequate for integrated acoustics applications. In order to overcome these size limitations a new type of microresonator was designed, developed, and tested. In this paper, theoretical calculations and measurements on two kinds of such devices (a corrugated waveguide filter and a microresonator structure) are presented and their possible applications are discussed.

Monolithic dielectric filters in integrated waveguide technology

Abstract: We propose here a method to design monolithic dielectric filters (MDF) for achieving new levels of performance. The filter consists of a high-permittivity dielectric slab placed in a waveguide below cutoff loaded with low-permittivity dielectric slabs. These filters are miniature, highly selective, with low losses and small level parasitic resonances. A new approach is based on the equivalent circuits used to model the waveguide dielectric resonator of the monolithic filter. This model shows how the resonance frequency and coupling coefficient can be applied to synthesize a prescribed passband having Chebyshev or maximally flat characteristics. Experimental results are presented in S- and X-band showing good agreement with the theory.

MIC Realization of Dielectric Resonator Elliptic Filters

Abstract: New configurations of dielectric resonator elliptic filters on MIC are proposed. A detailed procedure for desining bot. bandpass and bandstop filters is presented. Two trial samples of filters are constructed to demonstrate the principle.

Microstrip Quadruplexer using -3 dB Hybrids

Abstract: A periodic branching microstrip filter using -3 dB directional couplers and short lengths of microstriplines with improved frequency characteristics is described in this paper. The designed filter separates the 2-18 GHz input signal into four 4 GHz contiguous channels. The design of the periodic branching filter and experimental results are presented.

Intelligent techniques for electronic component and system alignment

Abstract: The application of intelligent systems is investigated for the automatic tuning of microwave waveguide filters and the alignment of quadrature-amplitude-modulated (QAM) digital microwave radio equipment. The intelligent techniques include conventional rule-based expert systems as well as a machine-learning system which combines techniques from pattern recognition and adaptive signal processing. These approaches are shown to significantly reduce the time and skill required for manual filter alignment and, in addition, they can readily diagnose both type and magnitude of selected faults in the radio communication equipment. This is accomplished via a set of feature data whose parameters are monitored under fault or misalignment conditions, and the deviations from a good pattern are used to adjust the device under test. The selection of appropriate features and alignment of sixcavity 11 GHz waveguide filters and 16-state QAM digital microwave radio-relay-system equipments are discussed.

Analyse électromagnétique d'un filtre à phase linéaire à iris inductifs épais

Abstract: In millimeter wevelength range, Iris, Waveguide side wall slots used to build filters and directional couplers should not be considered thin since their dimensions are not smaller than the wavelength. In this work, the rigorous mode matching technique is used to compute equivalent models for thick iris and thick rectangular waveguide side wall slots. We have applied those results to th design and the realization of millimeter waveguide linear phase filters, waveguide side wall thick slot couplers and thick iris waveguide filters.

A Direct Method of Synthesis for a Class of Waveguide Filters

Abstract: A direct method of synthesis on insertion loss basis is presented for symmetrical waveguide filters which can be modelled by a cascade chain of lumped parameter, reactive, symmetric two-ports and lengths of unimodal waveguide sections (Fig. 1). The presented method is rather general, easy to implement numerically and sheds physical insight into the complex propagation phenomena in waveguide filters. Hereby the synthesis of a N-section symmetric filter, where N is an odd integer, is reduced to the simultaneous solution of (N+l)/2 nonlinear equations which can be written down by inspection for given design perspectives. The achieved degree of accuracy in the design is remarkably good over bandwidths in excess of 60%.

Device for tuning the coupling between two waveguides

Abstract: The tuning of the coupling between two waveguides which are separated from one another by a coupling aperture is very tedious with known devices, since no defined change in the coupling level can be achieved with them. A defined tuning of the coupling is ensured by arranging at least one tuning screw (5, 5'), penetrating through the waveguide wall, in front of the coupling aperture (3) in the region of the coupling opening (4, 4'). The device according to the invention is suitable, for example, for use in waveguide filters in order to tune these to a desired characteristic with little effort.

Waveguide filters using expanded joints

Abstract: A method of constructing waveguide filters of the type incorporating inductive posts, or pins, so as to provide improved microwave performance avoiding the use of soldering or brazing alloys at the important electrical interfaces within the waveguide structure. Using high conductivity base metals, the method requires only cold-flow expansion to provide highly conducting, or low resistance, joints. Low conductivity base metals may also be used so that application of the construction technique includes both jointing prior to, and/or jointing subsequent to, the surface deposition of a highly conductive metal coating by known means. The pins are bored at their ends, and a member, e.g. a ball (4), of greater hardness and diameter is forced in to expand the tubular end of the pin into good contact with the waveguide wall.

Dielectric resonator in nonradiative dielectric waveguide bandstop filter

Abstract: Tfie dielectric resonator in Nonradiative Dielectric (NRD) waveguide is considered as a section of infinite long dielectric rod waveguide which is cut out by two infinite parallel metal plates. When it is used as resonant element of the MW waveguide bandstop filter, the theoretical resonant frequency of the daielectric resonator calculated by the method which is applied in this paper is in very good agreement with the experimental stopband center frequency of the filter.

CdTe Buffered GaAs Thin-Slab IR Waveguide Modulators and T/R Filter

Abstract: : Broadband electrooptic modulation and frequency shifting of CO2 lasers using GaAs thin-slab waveguides have been described previously. The performance of an unbuffered GaAs waveguide traveling-wave modulator has been found to yield a sideband power conversion efficiency of 4.5 + or - .0000045 or -43.6 dB for one watt of microwave drive power. This paper presents the performance of CdTe buffered GaAs waveguide modulator and describes the structural parameters that have been modified to gain 5 dB improvement from that provided by unbuffered IR waveguide modulators. CdTe buffered GaAs thin-slab waveguide modulators with very low optical and microwave insertion losses, have been fabricated. The measured single sideband power that can be converted from the CO2 laser input power is -39 dB for one watt microwave driver power, as compared to a measured value of -44 dB from an unbuffered modulator. The output beam quality has also been improved significantly. A transmission/reflection filter designed to separate the sidebands from the carrier has been fabricated and tested. The rejection ratio of carrier power to sideband power is -19 dB. Cadmium tellurides; Gallium arsenides; Waveguide modulators; Carbon dioxide lasers.

An investigation of NRD waveguide grating

Abstract: The authors present the equivalent network and the filter characteristics of a periodic NRD (nonradiative dielectric) guide structure. This structure can be used in a millimeter-wave dielectric waveguide integrated oscillator as a frequency stabilizer. The filter characteristics of the NRD waveguide grating are investigated rigorously by combining the network approach with mode matching theory. Numerical examples are shown and found to agree well with experimental results. >