Microwave Theory and Techniques, IRE Transactions on
This Transactions ceased publication in 1962. The current retitled publication is IEEE Transactions on Microwave Theory and Techniques.
Latest Published Articles

The ThreeLevel SolidState Maser
Jan06 2003 
Rectangular and Ridge Waveguide
Jan06 2003 
Propagation Constants of Circular Cylindrical Waveguides Containing Ferrites
Jan06 2003 
Nonmechanical Beam Steering by Scattering from Ferrites
Jan06 2003 
Some Properties of Image Circles
Jan06 2003
Popular Articles

An NWay Hybrid Power Divider
Jan06 2003 
A Method of Analysis of Symmetrical FourPort Networks
Jan06 2003 
A New Class of BroadBand Microwave 90Degree Phase Shifters
Jan06 2003 
ParallelCoupled TransmissionLineResonator Filters
Jan06 2003 
CoupledStripTransmissionLine Filters and Directional Couplers
Jan06 2003
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Popular Articles (November 2014)
Includes the top 50 most frequently downloaded documents for this publication according to the most recent monthly usage statistics.
1. An NWay Hybrid Power Divider
Page(s): 116  118A circularly symmetric power divider is described which splits a signal into n equiphase equiamplitude parts where n can be odd or even. The power divider provides isolation between output terminals and approximately matched terminal impedances over about a 20 per cent band. A theory of operation is given which yields the necessary design parameters, and an experimental model is described which has a minimum isolation of 27 db between output terminals, an output VSWR of 1.6, and an input VSWR of 1.2. View full abstract»

2. A Method of Analysis of Symmetrical FourPort Networks
Page(s): 246  252An analysis of fourarm symmetrical networks such as a branched directional double stub coupler or the hybrid ring (rat race) is presented. The input wave is broken into an even and an odd mode and the vector amplitude out the various arms is computed from the sums or differences of the reflection or transmission coefficients for the two modes. A zero decibel directional coupler is described and its possible use as a duplexer is proposed. The design of multiple stub directional couplers for any degree of coupling is discussed. A method of computing the bandwidth of all these couplers is outlined, and the bandwidth curves, the power out the various arms with respect to frequency of the zero decibel coupler, are computed. A tabulation is made for six different 3 db couplers (evenpower split) and their standing wave ratio, evenness of power split and isolation of the fourth arm as a function of frequency assuming perfect performance at the band center. View full abstract»

3. A New Class of BroadBand Microwave 90Degree Phase Shifters
Page(s): 232  237In the type of circuits considered here, the input power is divided equally between two channels whose outputs are caused to have a very nearly 90° phase difference over a broad frequency range. Networks suitable for application at low frequencies which perform the above function have been widely investigated. This report describes a new type of 90° differential phase shifter which has a constant resistance input, and which is useful over bandwidths as large as 5:1 in the microwave region. View full abstract»

4. ParallelCoupled TransmissionLineResonator Filters
Page(s): 223  231This paper describes the synthesis of bandpass transmissionline filters consisting of series of halfwavelength resonant conductors such as strips. The design differs from the usual endcoupled strip configuration in that successive strips are parallel coupled along a distance of a quarterwavelength. The resulting coupling between resonators is partly electric and partly magnetic. Several important advantages are gained by this arrangement: 1) the length of the filter is approximately half that of the endcoupled type; 2) the gaps are larger and therefore less critical; and 3) the insertionIoss curve is symmetrical on a frequency scale with the first spurious response occurring at three times the center frequency of the pass band. Formulas are derived for the parallelcoupledresonator transmissionline filter that permit accurate design for Tchebycheff, maximally flat, or any other physically realizable response. The formulas are theoretically exact in the limit of zero bandwidth, but frequencyresponse calculations show them to give good results for band widths up to about 30 per cent. An experimental stripline filter of this type has been constructed, and the data given in this paper show that excellent performance has been obtained. View full abstract»

5. CoupledStripTransmissionLine Filters and Directional Couplers
Page(s): 75  81This paper describes the theory of operation of coupled strip line tilt ers and directional couplers, and presents information from which these components may be easily designed. Lowpass, bandpass, allpass, and allstop filter characteristics are obtained from these coupled lines either by placing open or short circuits at two of the four available terminal pairs, or by interconnecting two of the terminal pairs. Directional couplers having perfect dkectivity and constant input impedance at all frequencies, and for all degrees of coupliig, are obtained by placing equal resistive loads at each of the four terminal pairs. View full abstract»

6. Characteristic Impedances of BroadsideCoupled Strip Transmission Lines
Page(s): 633  637Formulas are given for the even and oddmode characteristic impedances of shielded coupled striptransmissionline configurations that are especially useful when close coupling is desired. Applications may be made to wideband coupledstripline filters, 3db directional couplers, and many other components. The cross sections considered are thin broadsidecoupled strips either parallel or perpendicular to the ground planes. Modification of the formulas for thick strips is discussed. The derivations are outlined, with particular attention given to the underlying assumption that restricts the use of the formulas to cases of close coupling. View full abstract»

7. Propagation in Dielectric Slab Loaded Rectangular Waveguide
Page(s): 215  222Propagation in dielectric loaded rectangular waveguide is investigated theoretically for varying slab thickness and dielectric constant. The slabs are placed across the center of the waveguide in the E plane. This geometry is found to offer bandwidths in excess of double that of rectangular waveguide for dielectrics having dielectric constants of approximately 18. Power handling capacities which are double or triple that of standard waveguide are achievable using the dielectric loaded waveguide. In addition to the theory, design curves of bandwidth, guide wavelength, cutoff wavelength, impedance, power handling capacity, wall losses, and dielectric losses are presented and compared to experiment where possible. View full abstract»

8. Rectangular and Ridge Waveguide
Page(s): 201  209This paper describes the present state of the art with respect to rectangular ridge waveguide giving tables and data from standard waveguide sizes and constructional techniques for both rigid and flexible waveguide. The problems inherent in waveguide connectors are discussed along with the various methods for producing waveguide assemblies. The problems inherent with presentday waveguide standardization are also discussed. It is essential that a series of standard waveguide for high pressure operation and for extremely broadband operation (ridgeguide) be standardized. The latest RETMA miniature standard flanges are shown along with presentday thinking on a series of pressurized contact flanges. View full abstract»

9. Optimum Design of Stepped TransmissionLine Transformers
Page(s): 16  20This paper describes the optimum steppedtransmissionline transformer structure for matching two unequal characteristic impedances. For any specified bandwidth, the steps are designed to yield a Tchebychefftype (or equalripple) reflectioncoefficient response. Over this band, the maximum vswr is less than that obtainable with any other steppedtransformer having the same number of steps. Design method and technique for eliminating discontinuitycapacitance effects are given. The measured results for a coaxial and a waveguide model are presented and found to verify the method. View full abstract»

10. Periodic and Guiding Structures at Microwave Frequencies
Page(s): 30  61The paper reviews the properties of periodic and guiding structures which now play an important part in the operation of components, antennas, electron tubes and lownoise amplifiers. An account is first given of dispersive propagation in periodicloaded lines, showing how the frequency characteristic breaks into pass and stop bands. The formation of forward and backwardspace harmonics and the effect of systematic modification of loading are examined. A description is then given of the various types of surfacewave structures including dielectric rods, dielectricclad metals, and corrugated surfaces, as well as surface wave instruments and circuits. Practical slowwave structures such as ladder lines, coupled cavities and helices are finally treated. The survey concludes with a bibliography. View full abstract»

11. A WideBand Balun
Page(s): 314  316Experimental results are given for a transformer from an unbalanced 50ohm coaxial line to a balanced pair of 50ohm coaxial lines. The design is one proposed by Marchand. The balance, standing wave ratio, and insertion loss are nearly constant over a 13 to 1 frequency range from 650 mc to 8500 mc. The standing wave ratio is less than 2.1 to one and the insertion loss is about 0.5 db over this band of frequencies. View full abstract»

12. Shielded CoupledStrip Transmission Line
Page(s): 29  38An analysis is made of the odd and even TEM modes on a pair of parallel coplanar strips midway between ground planes. Rigorous formulas are presented for the case of zerothickness strips, while approximate formulas are given for strips of finite thickness and for strips printed on opposite sides of a thin dielectric sheet supported in air between ground planes (AIL construction). The characteristic impedances and the phase velocities of the two modes are necessary and sufficient information for the design of directional couplers, coupledline filters, and other components utilizing the coupling between parallelstrip lines. In order to facilitate design work, nomograms are included in the paper which give the dimensions of the coupledstrip cross section in terms of the odd and evenmode characteristic impedances. The characteristicimpedance scales of these nomograms may be read to an accuracy of better than one per cent over a wide range of values that is sufficient for most purposes. View full abstract»

13. The Design of Ridged Waveguides
Page(s): 20  29As far as we are aware, the only published design information on ridged guide transmission lines is found in a paper by S. B. Cohn and to some extent in the Waveguide Handbook. Recent applications, however, have indicated a need for additional and, in some cases, more accurate design information. The present paper is largely written with this in mind. View full abstract»

14. A Dielectric Resonator Method of Measuring Inductive Capacities in the Millimeter Range
Page(s): 402  410A novel technique for the measurement of dielectric and magnetic properties of a homogeneous isotropic medium in the range of approximately 3 to 100 kmc is described. An accuracy of /l.chemc/ 1 per cent is possible in the determination of permittivity or permeability in those cases where the loss tangent is sulliciently small. The measuring structure is a resonator made up of a right circular cyndrical dielectric rod placed between two parallel conducting plates. For measurement of permittivity two or more resonant TE_{onl} mode frequencies are determined whereas for the measurement of permeability two or more resonant TM_{onl} mode frequencies are determined. The dielectric or magnetic properties are computed from the resonance frequencies, structure dimensions, and unloaded Q. Since the loss tangent is inversely proportional to the unloaded Q of the structure, the precision to which Q is measured determines the accuracy of the loss tangent. View full abstract»

15. A New Type of Circular Polarizer Using Crossed Dipoles
Page(s): 385  388A method of obtaining a circularlypolaIized wave by use of two orthogonal dipoles driven in parallel by a common transmission line is shown. The lengths of the dipoles are so chosen that the real part of their input admittances are equal and the angle of the inpnt admittances differ by 90°. When these two conditions are met the resulting radiated wave in a normal direction will be circularly polarized. The method is applicable both to a circularlypolarized radiating antenna and to the problem of producing a circularlypolarized wave of the TE_{1} mode in a round waveguide. For the first case, an analysis and a method of design are shown, and for the second case an experimentally developed example is given. The second case employs monopoles rather than dipoles for convenience in energizing from a coaxial line. View full abstract»

16. Design of WideBand (and NarrowBand) BandPass Microwave Filters on the Insertion Loss Basis
Page(s): 580  593A method for design of bandpass microwave filters is described that combines the image and insertionloss points of view to give an approximate design method having simplicity, but also high precision. This method is applicable for filter designs ranging from narrow to very wide bandwidths (2 to 1 or more). The desired insertion loss characteristic is obtained by use of a lumpedelement, Tchebycheff, or maximally flat (or other) lowpass prototype. With the aid of the concept of impedance inverters, the prototype is converted into a cascade of symmetrical (but differing) sections. The image properties of symmetrical sections of the bandpass microwave filter structure are then related to those of corresponding sections of the prototype. Straightforward design equations are given for filters using shortcircuited or opencircuited stubs, and also for filters using parallelcoupled lines. Mapping functions are derived that permit accurate prediction of the microwave filter cutoff characteristic from that of the prototype. The responses of a number of filter designs were computed, and a Tchebycheff filter with a 2.2 to 1 bandwidth was built and tested. The reponses of all of the filter designs were in close agreement with the prescribed characteristics, and the accuracy of the mapping functions was verified. View full abstract»

17. SteppedImpedance Transformers and Filter Prototypes
Page(s): 339  359Quarterwave transformers are widely used to obtain an impedance match within a specified tolerance between two lines of different characteristic impedances over a specified frequency band. This paper gives design formulas and extensive tables of designs, most of which were especially derived so that an integrated account could be presented for the first time. Numerous examples are given. Only homogeneous, synchronous transformers and filters are included in this paper, but a short bibliography on related topics is appended. The theory is also applied to bandpass filters, by showing how to convert quarterwave transformers into halfwave filter prototypes. The theoretical and numerical results presented are applicable to the design of impedance transformers, directcoupled cavity filters, shortline lowpass filters, optical antireflection coatings and interference filters, acoustical transformers, branchguide directional couplers, TEMmode coupledtransmissionline directional couplers, and other circuits. These applications have been or will be dealt with in separate papers; this paper gives the basic theory and some of the numerical data required for these applications. View full abstract»

18. The Measurement of Conductivity and Permittivity of Semiconductor Spheres by an Extension of the Cavity Perturbation Method
Page(s): 545  551A technique based on cavity perturbation theory is described with which one can determine the microwave conductivity and dielectric permittivity of a small sphere of completely arbitrary conductivity. These properties follow from the measured frequency shift and quality change occurring when the sample is inserted into a region of maximum electric field in a cavity resonator. The range of validity of the quasistatic internal field approximation is discussed, and curves are provided for extending the measuring technique beyond this range. The extended theory is valid for the entire conductivity range from zero to infinity. Measurements on several samples of known conductivity and permittivity in which the approximation is not satisfied are seen to agree with the theory. For highly conductive materials, the present method is closely related to the "eddy current loss" measuring technique discussed by others. The two methods are compared from the point of view of perturbation theory in order to determine their relative merits. Because the measuring technique employs a spherical sample, it may be applied profitably to materials with nonisotropic carrier nobilities and to semiconducting materials for which contact fabrication techniques are poorly known. View full abstract»

19. Problems in Strip Transmission Lines
Page(s): 119  126A review is given of characteristicimpedance formulas for shieldedstrip transmission lines. From these formulas a set of approximate relationships for the attenuation and Q of a dielectricfilled shieldedstrip transmission line is derived. The method makes the standard assumption that the current distribution is that of a lossless line and the surface resistivity that of an infiniteplane condutor. Although this method applies accurately to most other types of lines, in this case an error of the order of 10% is believed to occur due to the failure of the assumptions at the corners of the strip. However, the error is in a direction that makes the computed values conservative, and the accuracy should be sufficient for most practical purposes. The derivation of a correction term is now being attempted. In addition to the discussion of attenuation attention is given in this paper to the design considerations involved in a shieldedstripline impedance meter, and to some preliminary data obtained with this device. Also the future topics for investigation under this research and development program are mentioned. View full abstract»

20. The Multiple Branch Waveguide Coupler
Page(s): 398  403A multiple branch directional coupler is discussed for rectangular waveguide applications for series junctions. A design method is developed which is valid for any coupling ratio and any number of branch lines with perfect match and directivity. The frequency response of this type coupler is calculated with the aid of a digital computer. View full abstract»

21. Tables for Cascaded Homogeneous QuarterWave Transformers
Page(s): 233  237Quarterwave transformers are frequently required in microwave and UHF systems. An exact design procedure is known but involves lengthy calculations. Faced with the design of many such transformers, the calculations were programmed on an IBM 704 digital computer. The speed of computation is such that several hundred designs for 2, 3, and 4 section transformers were systematically computed in a few minutes. The results are reproduced here in tables, which should permit the calculation of most cases of practical interest by interpolation. View full abstract»

22. A Printed Circuit Balun for Use with Spiral Antennas
A novel printed circuit balun is described which is particularly well suited to applications where space is at a premium. The design utilizes unshielded strip transmission line, but is readily adaptable to all of the common printed circuit transmission line techniques. When the balun is housed within the cavity of a spiral antenna, boresight error is virtually eliminated, ellipticity ratios of less than 2 db are maintained over an azimuth angle greater than ± 60°, and the input standingwave ratio is less than 2:1 over an octave frequency range. Experimental results are given and additional applications are described. View full abstract»

23. General Synthesis of QuarterWave Impedance Transformers
Page(s): 36  43This paper presents the general synthesis of a radio frequency impedance transformer of n quarterwave steps, given an "insertion loss function" of permissible form. This procedure parallels that of Darlington for lumped constant filters by providing the connection between Collin's canonical form for the insertion loss function and Richards' demonstration that a reactance function may always be realized as a cascade of equal length impedance transformers terminated in either a short or open circuit. In particular, it is shown that insertion loss functions of the form selected by Collin are always realizable with positive characteristic impedances, and that the synthesis procedure, for maximally flat and Tchebycheff performance, involves the solution, at most, of quadratic equations. In addition, this procedure permits the proof of Collin's conjecture that, for his insertion loss function, the resulting reflection coefficients are symmetrical. Finally, closed expressions are given for the coefficients of the input impedance of a given n section transformer in terms of the n characteristic impedances and vice versa. View full abstract»

24. Interdigital BandPass Filters
Page(s): 479  491The design of bandpass filters using interdigital arrays of resonator line elements between parallel ground planes is discussed. Two approximate design procedures are described, both of which permit design directly from lumped element, lowpass, prototype filters. Both design procedures will work for either narrow or wideband filters, but one procedure gives more practical dimensions for filters having wide bandwidths (such as an octave), while the other gives more practical dimensions for filters having narrow or moderate bandwidth. The resulting filters are very compact, have relatively noncritical manufacturing tolerances, and strong stop bands with the second pass band centered at three times the center frequency of the first pass band. The dimensions and measured performance curves are presented for a 10 per cent bandwidth design and an octave bandwidth design. View full abstract»

25. CoupledTransmissionLine Directional Couplers
Page(s): 403  410Formulas are presented for the design of coupledtransmissionline directional couplers that are rigorous for any value of coupling. Two basic types are treated in detail; the simplest is onequarter wavelength long at the center of its frequency band, while the other is threequarter wavelength long. The quarterwavelength type can be used over an octave of frequencies with approximately consistant coupling, while the threequarterwavelength type can be used equally well over more than two two octaves. For example, a 3db coupler of the first type has a variation of +0.3 db over a 2:1 band, while the second type has the same variation over a 4.5:1 band. Theoretically both types should have infinite directivity at all frequencies. The experimental results for models of these directional couplers have been found to conform very closely to the theoretical coupling functions, while the directivity, although usually good, is limited by discontinuity effects and constructional tolerances. View full abstract»

26. The Synthesis of Symmetrical Waveguide Circulators
Page(s): 238  246A method for synthesizing symmetrical waveguide circulators by adjusting the eigenvalues of the scattering matrix is described. This procedure is particularly useful for the design of very compact circulators in the form of waveguide junctions containing ferrite obstacles. Permissible structural symmetries for a circulator are listed, and a standard form for the scattering matrix of a symmetrical circulator is defined. The synthesis procedure is then described in detail, stating the conditions to be imposed on the scattering matrix eigenvalues, and an expression is obtained for the changes in the eigenvalues due to the placing of anisotropic material within the junction. By applying the theory to Allen's 4port turnstile circulator, it is shown that the use of a matched turnstile junction and a reflectionless Faraday rotator is not essential. The theory is also applied to the design of novel 3 and 4port circulators, and two 6port circulators, one of which may be used as a 5position waveguide switch, are described. Some experimental results are presented for a compact 3port circulator in the form of an Hplane Y junction, in 1 inch by 1/2 inch waveguide, containing a ferrite post obstacle. This circulator, which operates with a bias field of approximately 25 oersted, has a useful bandwidth of 3 per cent. Greater bandwidths would be expected in a Stripline or a finline version of this device. View full abstract»

27. Velocity Modulation of Electromagnetic Waves
Page(s): 167  172This paper deals with electromagnetic wave propagation through dielectric media whose propagation constants vary as a function of time. If the parameters of the medium cannot respond to changes in the electric and magnetic fields of the propagating wave, the fields within such media will be linear. Maxwell's equations are solved for cases in which the scalar permittivity and permeability vary independently with time. When the impedance is constant, an exact solution is obtained. When the impedance varies, a closed form approximation is found since an exact solution is not always possible. The field energy and electromagnetic momentum are derived for a velocity transient and it is seen that, in general, the energy changes and the momentum remains constant. The frequency deviation that results when a monochromatic wave is passed through a section of dielectric with nonconstant velocity of propagation is discussed in detail. An approximate solution is obtained for the case in which the electrical length of such a section is small; it is found that essentially linear phase modulation occurs. The general solution is found for the case in wtilch the electrical length of section is long and the permittivity of the medium sinusoidally modulated. The optimum length found to give the greatest frequency deviation is shown to be generally impracticable. It appears that ferroelectric or ferrimagnetic velocitymodulated dielectrics are feasible, at least for lowpower modulators. View full abstract»

28. HybridRing Directional Coupler for Arbitrary Power Divisions
Page(s): 529  535A directional coupler in the form of a hybrid ring is described in this paper. A theoretical analysis using the scattering matrix has been carried out and experimental verification of the theoretical result has been achieved in a stripline network. Simple design equations which enable one to design a directional coupler with any degree of coupling have been derived. This coupler differs from the commonly used couplers in that the voltages at the output arms are either inphase or oppositephase with respect to each other. In addition, its geometrical symmetry makes it very convenient for use in symmetrical networks, particularly as a power divider in antenna feeding systems. View full abstract»

29. Propagation Constants in Rectangular Waveguide Partially Filled with Dielectric (Correspondence)
Page(s): 294There is considerable current interest in the production of guided electromagnetic waves having phase velocities equal to or less than the speed of light in free space (for example, in the design of travelingwave slot antennas and of devices involving electron travelingwave interactions). Such phase velocities can be obtained conveniently by partially loading a rectangular waveguide with dielectric material. In antenna work particularly, because of the field configurations, it is usually desirable to place the dielectric interface so that it is parallel to the broad face of the waveguide, as indicated in Fig. 1. The calculation of phase velocities in such a waveguide has been considered in the literature, and there is published information on some of the cutoff frequencies, but (since in this case there is no convenient relationship between the cutoff frequencies and the propagation constants) there has been little detailed information available concerning the phase velocities as a function of waveguide proportions and dielectric material. Thus a compilation has been made of such information for the dominant (hybrid) mode. View full abstract»

30. A VariableRatio Microwave Power Divider and Multiplexer
Page(s): 227  229A microwave circuit is presented which provides continuous variation of microwave power between two outputs in any desired ratio. A typical device utilizing the circuit is described, and other uses of the circuit are discussed. An Xband power divider was constructed which had a vswr of less than 1.2 at all times over the frequency range of 8.6 to 9.6 kmc, divided the total input energy between the outputs in any ratio from 1/10,000 to 1, and had less than 0.4db total insertion loss. No other losses were present. Adjustment could be made under maximum power levels of the waveguide. Another use of the circuit is to couple two highpower transmitters into one output, thus providing a dual frequency antenna coupler or diplexer. By cascading diplexers, multiplexing can be accomplished. View full abstract»

31. A Note on the Difference Between Equiangular and Archimedes Spiral Antennas (Correspondence)
Page(s): 203  205There seems to exist in the literature considerable confusion about the various types of spiral antennas, their characteristics, and their bandwidth capabilities. One evidence of this confusion appeared in a paper by Bower and Wolfe, in which they state that the Archimedes spiral antenna can be specified in terms of angles and hence belongs in the class of "frequencyindependent antennas. "Frequencyindependent antennas are relatively new; in fact, until 1955 there was no evidence that a "frequencyindependent" antenna did, indeed, exist. Therefore, it would appear appropriate to delineate the characteristics and the terminology of the antennas involved. Perhaps this brief report of some recent work at the University of Illinois Antenna Laboratory will aid in pointing up the differences in operation of the logarithmic (i.e., equiangular) and Archimedean spiral antennas. View full abstract»

32. Thickness Corrections for Capacitive Obstacles and Strip Conductors
Page(s): 638  644Capacitive thickness corrections are derived exactly for two basic geometries involving pairs of semiinfinite plates. In one arrangement the pair of plates are coplanar, while in the other they are parallel to each other. In each case the total capacitance per unit length between the pair of plates is infinite, but the incremental increase of capacitance when the thickness is increased from zero to a value t is finite. These capacitance increments are evaluated, and it is shown how they may be used as approximate thickness corrections in a great varity of more complicated geometries involving capacitive obstacles in waveguide, coaxial line, and artificial dielectric media. They may also be applied to coupledstripline conductors. As examples, the corrections are applied in detail to a waveguide iris, and to three useful coupledstripline cross sections. View full abstract»

33. Calculation of the Parameters of Ridge Waveguides
Page(s): 12  17In this paper an algebraic expression which constitutes an approximation to Cohn's transcendental equation is given for the determination of the dominantmode cutoff wavelength of ridge waveguides. A modified derivation of Mihran's equation for calculating the characteristic impedance of ridge waveguides is discussed. Based upon these formulas, nomography are constructed to permit the determination of these parameters with sufficient accuracy when the waveguide and the ridge dimensions vary. Experimental verification of the calculated cutoff wavelength is included. View full abstract»

34. The Use of Exponential Transmission Lines In Microwave Components
Page(s): 124  132This paper describes some techniques for utilizing exponential transmission lines in microwave components in order to reduce element lengths, and hence size and weight, and to significantly increase the operating frequency range. Formulas are developed which relate line length to the frequency and rate of taper for transmission line resonators, and a nomogram is included for easy determination of spurious frequencies. Additional formulas are given for the distributed representation of lumped elements using exponential sections of both coaxial and strip transmission line, and their use described in application to microwave filters and related components. In addition, the paper describes how unusually large rejection bandwidths can easily be obtained by proper selection of the individual element lengths and rates of taper. View full abstract»

35. Equivalent Circuits for Discontinuities in Balanced Strip Transmission Line
Page(s): 134  143Theoretical formulas are derived for the equivalent circuit parameters of a variety of discontinuties in balanced strip transmission line. These formulas are simple in form and are obtained by employing a small aperture procedure or a Babinet equivalence procedure in conjunction with an approximate model of the line. The results for a number of discontinuities are presented and comparison is made with the available measured data. View full abstract»

36. Application of RayleighRitz Method to Dielectric Steps in Waveguides
Page(s): 177  184The RayleighRitz method is applied to obtain approximations to the first N eigenfunctions and corresponding eigenvalues in an inhomogeneously filled rectangular waveguide. These approximate eigenfunctions are then used to obtain a solution for the reflection and transmission coefficients at the junction of an empty and partially filled waveguide. Theoretical and experimental results are given for a dielectric slab which extends completely across the broad dimension of the guide, but only partially across the narrow dimension. The experimental values are within the experimental error of the computed values obtained by considering the dominant mode and only two evanescent modes. View full abstract»

37. Coupled Rectangular Bars Between Parallel Plates
Page(s): 65  72Curves are presented giving the evenmode fringing capacitance, the oddmode fringing capacitance, and the difference between odd and evenmode fringing capacitances for wide ranges of thickness and spacing of rectangular bars centered between parallel plates. Simple formulas are given relating these capacitances to even and oddmode characteristic impedances of coupled rectangular bars. possible applications to stripline and other circuits are described. The appendix gives the derivation of the fringing, capacitances by conformal mapping techniques. The results are exact for bars extending in width infinitely far from the coupling region, and have only small error (less than 1.24 per cent) for bars whose width is greater than about 35 per cent of the difference between plate spacing and bar thickness. View full abstract»

38. Some Notes on the Optimum Design of Stepped TransmissionLine Transformers
Page(s): 374  378This paper describes an optimum design of monotonic stepped transmissionline transformers when the reflection coefficient and the bandwidth ratio are prescribed. For the analysis, discontinuity capacitances and reflection interactions are neglected and the validity of the conclusions is therefore restricted to small steps. The analysis is applicable to a multistep transmission line of which the quarterwave transformer is a special case. In particular, it is shown that if the number of steps is increased from three to five a larger bandwidth may be obtained, but it is not possible to reduce the overall length in this manner. For a given bandwidth, the shortest taper is always a stepped transmission line and never a continuous one. View full abstract»

39. A WideBand StripLine Balun
Page(s): 128  134A new wideband stripline balun that uses a pair of dual coupledstripline bandpass filters is described. It can operate over bandwidths up to about 8:1 in the frequency range of about 100 to 10,000 mc. Design data and theoretical performance curves for typical wideband baluns of this type are presented. The measured performance of an experimental balun operating over a 3:1 frequency range centered at 3000 mc is compared with the theoretical performance, and the effects of discontinuities and dissymmetries in the experimental balun are discussed. View full abstract»

40. Analysis of Microwave Measurement Techniques by Means of Signal Flow Graphs
Page(s): 206  212Microwave measurement techniques can be analyzed more simply by using signal flow graphs instead of the customary scattering matrices to describe the microwave networks used in the measuring system. This is because the flow graphs of individual networks are simply joined together when the networks are cascaded and the solution for the system can be written down by inspection of the overall flow graph by application of the nontouching loop rule. This paper reviews the method of setting up flow graphs of microwave networks and the rule for their solution. A single directionalcoupler reflectometer system for measuring the reflection coefficient of a load is then analyzed by this method. The analysis shows how auxiliary tuners can be used to cancel residual error terms in the measurement of the magnitude of the reflection coefficient at a particular frequency. The analysis also shows how an additional tuner can be used to measure the phase angle of the reflection coefficient. These reflectometer techniques are particularly useful in the measurement of very small reflections. View full abstract»

41. Design Considerations for HighPower Microwave Filters
Page(s): 149  153The need for highpower filters is reviewed briefly, and various design approaches are discussed. The major portion of the paper treats the powerhandling capacity of multipleresonator filters using inductive windows or posts as coupling elements. A formula is derived that gives the relative power capacity of a waveguide filter of this type in terms of the bandwidth and cavity dimensions, and the element values of the lowpass prototype filter. By means of this formula it is shown quantitatively how highpower ratings may be achieved through the use of enlarged cavities. Methods for eliminating spurious filter responses and of reducing the reflected energy are discussed. View full abstract»

42. A BroadBand Microwave Circulator
Page(s): 210  217The discovery of a simple, low loss way to hold Faraday rotation constant over a broadband (coupled with the development of wideband, high return loss, circulartorectangular waveguide transformers, and polarization couplers) has made it possible to design and build a high quality circulator for use in the 10.7 kmc to 11.7 kmc band. The essential characteristics of the described unit include a more than 30db return loss at each terminal, an isolation of 30 db or greater between "isolated" terminals, and a 0.35db insertion loss between transmission terminals. View full abstract»

43. BroadBand Directional Couplers
Page(s): 251  257It is shown how to connect two identical hybrids to obtain a directional coupler of arbitrary power division that operates over a broader band than that of the components. The broadbanding technique is possible with a certain kind of hybrid that includes Riblet couplers, multihole hybrids, coaxial hybrids and semioptical hybrids, but excludes T hybrids and ring hybrids. Riblet couplers have a geometry particularly adaptable to the broadbanding technique. Where the balance of one of these couplers is better than 1 db, the balance of the broadband hybrid can be made better than 0.16 db. The broadbanding technique is particularly effective in the case of the 100 per cent transfer directional coupler type of circuit used for band separation filters and RADAR duplexers. In the semioptical waveguide bandsplitting filters the bandwidth can be increased from about one to about four octaves (3575 kMc to 35580 kMc). View full abstract»

44. Discontinuities in the Center Conductor of Symmetric Strip Transmission Line
A systematic measurements program has been carried out to check the validity of theoretical formulas for the equivalent circuit parameters of a variety of discontinuities in the center conductor of symmetric strip transmission line. These theoretical formulas have been in part previously available and are in part new or modified. Results indicate that, in general, these formulas are adequate for most engineering purposes and that certain of the network parameters can be neglected. View full abstract»

45. Microwave Variable Attenuators and Modulators Using PIN Diodes
Page(s): 262  273The PIN diode is a double diffused junction with an intrinsic layer separating the P and N regions. At frequencies above 100 Mc, the diode ceases to be a rectifier because of carrier storage and transit time effects. Its shunt capacitance is quite small because of the separation of the P and N regions by the I layer. Conductivity of the I region can be varied by a dc bias current and the device becomes an electrically variable resistor which can be used for microwave attenuators and modulators up to frequencies as high as 20 Gc. The PIN junctions are mounted on posts which are inserted in a 50ohm strip transmission line as shunt elements, and a number of these elements, spaced a quarter wavelength apart at midband, are used to form an attenuator. At the appropriate bias current, yielding 50ohm junction resistances, the diode elements are reactively compensated by choice of post dimensions so that they are effectively pure resistances, yielding an image attenuation of 4.2 db per element. Many elements can be used to attain any desired total attenuation and higher impedance end elements can be used to improve the SWR. Bandwidths of 4 to 1 with low SWR in both ON and OFF conditions are achievable. Maximum attenuation of 60 db, insertion loss of 1 db, and SWR of 1.5 are typical for a 12diode attenuator and powers of the order of watts can be handled with negligible harmonic generation. When used as a pulse modulator, rise times of the order of 10 nsec are achievable. View full abstract»

46. A Method of Analysis of Symmetrical FourPort Networks (Correspondence)
Page(s): 162  163The following errors appeared in the above article. On page 248 the C term in the matrix for Fig. 11 should be j(a²c²+2ac+a²1). Also, on page 249 the term for T+ for the rat race ring should be T+ = j/spl radic//bar 2/. View full abstract»

47. Parallel PushPull Hybrid Circuit
Page(s): 34  40This paper deals with a new hybrid circuit for signal branching or combining in parallel pushpull amplifiers. The purpose of the new hybrid circuit is to perform the branching or combining of two pairs of signals for parallel pushpull operation, each consisting of two oppositely phased, balanced signals. The advantage of combining two pairs of parallel pushpull signals by a single component of new hybrid circuit is clear; one would require a multiplicity of conventional ratrace circuits to do the same job, inasmuch as the basic ratrace circuit is limited to only one pair of pushpull signals. The new hybrid circuit is further elaborated to improve the performance for combining unbalanced pushpull signals by: (1) showing that the combination of unbalanced pushpull signals is equivalent to the superposition of cophase components on the balanced antiphase components; (2) analyzing the effect of the cophase components in the hybrid circuit; and (3) devising means of improving the adverse effects of the cophase components. Finally, an evaluation is made of a parallel pushpull amplifier using the new hybrid circuit in comparison with the conventional ratrace circuits required for the same parallel pushpull operation. View full abstract»

48. Operation of the Field Displacement Isolator in Rectangular Waveguide
Page(s): 605  611A field displacement isolator in WR159 rectangular waveguide consisting of a full height ferrite slab having a resistive film on one face is treated analytically. The resultant transcendental equation was programmed for a computer and values of the propagation constant found in the frequency range 5.90 to 6.45 kMc for various film resistivities. Two TE modes are found to exist whose relative behavior depends on the resistivity of the film. Reasonably close experimental verification of the results was obtained. for the total attenuation and for the predicted Efield distributions by Efield probe tests. Additional attenuation above that predicted by the theory for a single mode is observed as a result of an interference at the end of the ferrite. A partial height ferrite slab isolator was subjected to Efield probe tests. The field distributions were found to be similar to the full height case. Here, also, additional attenuation is obtained at some frequencies as a result of an interference. View full abstract»

49. On the TE_{n0} Modes of a Ferrite Slab Loaded Rectangular Waveguide and the Associated Thermodynamic Paradox
Page(s): 81  95It has been known for some time that the secular equation for the TE_{n0} modes of a perfectly conducting rectangular waveguide loaded with a transversely magnetized dissipationless full height ferrite slab located against one of the narrow walls of the waveguide admits the possibility of the existence of only a single propagating mode (transporting energy in one direction only). In this paper, it is established that if we admit the existence of a passive dissipationless uniform waveguide supporting only a single propagating mode we are led inescapably to a thermodynamic paradox. A uniqueness theorem is cited to establish that, for the waveguide described above, the paradox is associated with the TE_{n0} mode set alone. This conclusion motivates a thorough study of the secular equation for the TE_{n0} modes of this waveguide. This study is initiated by an investigation into the properties of the TE_{n0} surface waves guided along a plane interface separating a transversely magnetized dissipationless ferrite from free space. It is shown that two oppositely directed surface waves are guided along this interface. These two surface waves are admitted in different finite ranges of the parameter values which never coincide and which may or may not overlap. Each of the two surface waves has both a high and a lowfrequency cutoff and, in general, both a high and a low dc magnetic field cutoff. The propagation constant of one of the surface waves becomes infinite at the low field (highfrequency) cutoff. The next step in the analysis consists of an examination of the behavior of these surface waves on finite thickness ferrite slabs located in different environments. It is shown that when one of the two interfaces bounding the slab approaches a short circuit the infinite propagation constant noted above behaves in a peculiar discontinuous fashion. Next, the TE_{n0} mode secular equation of the slab loaded rectangular waveguide is analyzed and information is developed leading to a description of the behavior of the propagation constants of all the propagating TE_{n0} modes. This analysis reveals that the possibility of the existence of only a single propagating mode is associated only with the surface wave mode of this waveguide. A resolution for the  thermodynamic paradox is proposed based on the discontinuous behavior of one of the infinite propagation constants associated with this surface wave mode. It is shown that with a properly chosen secular equation for the waveguide under consideration there are always an even number of TE_{n0} propagating modes, half of which transport energy in one direction, half in the other. This demonstration is based, in part, on an analysis leading to relations between the direction of the power flow associated with a propagating mode and the derivative of its propagation constant with respect to the dc magnetic field. View full abstract»

50. Design and Development of StripLine Filters
Page(s): 86  93Strip transmission lines offer an alternate medium in which microwave filters can be realized. Since bandpass filters designed in waveguide or coaxial lines would necessarily be large at ultrahigh frequencies, strip lines provide a practical means of realizing filters which are simply fabricated and which represent an appreciable saving in size and weight. View full abstract»
Aims & Scope
This Transactions ceased publication in 1962. The current retitled publication is IEEE Transactions on Microwave Theory and Techniques.
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Frequency: 6
ISSN:
00972002
Subjects
 Fields, Waves & Electromagnetics
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 ( 1955  1962 ) Microwave Theory and Techniques, IRE Transactions on
 ( 1953  1955 ) Microwave Theory and Techniques, Transactions of the IRE Professional Group on