Showing papers in "IEEE Transactions on Microwave Theory and Techniques in 1958"
TL;DR: In this article, the authors describe the synthesis of band-pass transmission-line filters consisting of series of half-wavelength resonant conductors such as strips, which differs from the usual end-coupled strip configuration in that successive strips are parallel coupled along a distance of a quarter wavelength.
Abstract: This paper describes the synthesis of band-pass transmission-line filters consisting of series of half-wavelength resonant conductors such as strips. The design differs from the usual end-coupled strip configuration in that successive strips are parallel coupled along a distance of a quarter-wavelength. 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 end-coupled type; 2) the gaps are larger and therefore less critical; and 3) the insertion-Ioss 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 parallel-coupled-resonator transmission-line 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 frequency-response calculations show them to give good results for band widths up to about 30 per cent. An experimental strip-line filter of this type has been constructed, and the data given in this paper show that excellent performance has been obtained.
549 citations
TL;DR: In this paper, the authors describe 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.
Abstract: In 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.
469 citations
TL;DR: In this article, the electromagnetic wave propagation through dielectric media whose propagation constants vary as a function of time was studied, and it was shown that 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.
Abstract: This 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 velocity-modulated dielectrics are feasible, at least for low-power modulators.
306 citations
TL;DR: In this article, the authors investigated propagation in dielectric loaded rectangular waveguide for varying slab thickness and dielectrics constant and found that power handling capacities which are double or triple that of standard waveguide are achievable using the dielectoric loaded waveguide.
Abstract: Propagation 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.
123 citations
TL;DR: In this paper, it was shown that a reentrant cavity can be expressed as a low-frequency series LCR/sub se/ circuit or a shunt L CR/sub sh/ circuit, taking L as the inductance of a toroidal coil with one turn and with a cross section the same as the cavity, C as the gap capacitance plus the equivalent capacitance of the cavity.
Abstract: Klystron resonant cavities are treated for general cases and their equivalent circuits are theoretically determined, which allows a fairly accurate estimate of resonant properties. It is shown that a reentrant cavity is expressed as a low-frequency series LCR/sub se/ circuit or a shunt LCR/sub sh/ circuit, taking L as the inductance of a toroidal coil with one turn and with a cross section the same as the cavity, C as the gap capacitance plus the equivalent capacitance of the cavity, and R/sub se/ or R/sub sh/ as the equivalent series or shunt resistance of the cavity at resonance. The introduction of the equivalent cavity capacitance has proved to be very effective. The formulas derived here enable one to calculate the resonant frequency within an error of a few per cent and the shunt resistance and the Q within an error of several tenths of a per cent in most cases, and thus should prove to be very useful to the designer of microwave circuits.
122 citations
TL;DR: In this paper, a multiple branch directional coupler is proposed for series junctions with perfect match and directivity, and the frequency response is calculated with the aid of a digital computer.
Abstract: A 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.
102 citations
TL;DR: In the theory of cavity resonators, the assumptions are frequently made that every irrotational function can be represented as the gradient of a scalar and that every divergenceless function as the rotation of a vector.
Abstract: In the theory of cavity resonators, the assumptions are frequently made that every irrotational function can be represented as the gradient of a scalar and that every divergenceless function can be represented as the rotation of a vector. These are, however, not necessarily correct. This paper corrects these misleading assumptions and describes "the theory of cavity resonators" which supplement the classical theory of Slater.
99 citations
TL;DR: In this article, the anisotropic properties of an infinite stack of thin dielectric sheets separated by another set of thin sheets with a different Dielectric constant are investigated, and it is shown that the two distinct modes of propagation can exist in such a stacked array of sheets.
Abstract: The anisotropic properties of an infinite stack of thin dielectric sheets separated by another set of thin sheets with a different dielectric constant is investigated. It is shown that the anisotropic properties are brought about because of the two distinct modes of propagation which can exist in such a stacked array of sheets. The limiting forms of the wave solutions and second-order results for the equivalent dielectric constants are given.
69 citations
TL;DR: In this paper, it was shown that the usual reciprocity statements for isotropic media apply to gyrotropic medium if one reverses the dc magnetic field whenever an interchange of source and is made.
Abstract: Reversal of the dc magnetic field in gyrotropic media transposes the tensor permeability and permittivity. It is shown that this also transposes the impedance, admittance, and scattering matrices any device. It follows from this that the usual reciprocity statements for isotropic media apply to gyrotropic media if one reverses the dc magnetic field whenever an interchange of source and is made.
66 citations
TL;DR: In this paper, the design of coupled-transmission-line directional couplers is presented for any value of coupling, and two basic types are treated in detail; the simplest is one-quarter wavelength long at the center of its frequency band, while the other is three-quarter length long.
Abstract: Formulas are presented for the design of coupled-transmission-line directional couplers that are rigorous for any value of coupling. Two basic types are treated in detail; the simplest is one-quarter wavelength long at the center of its frequency band, while the other is three-quarter wavelength long. The quarter-wavelength type can be used over an octave of frequencies with approximately consistant coupling, while the three-quarter-wavelength type can be used equally well over more than two two octaves. For example, a -3-db 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.
66 citations
TL;DR: In this paper, the principles that led to the conception of the traveling-wave resonator and the calculations enabling its operation are presented, and the apparatus in detail and examines it, bearing in mind its use as high-power testing equipment.
Abstract: In the first part of the paper, the principles are given which have led to the conception of the traveling-wave resonator, and the calculations enabling its operation to be understood are presented. The second part describes the apparatus in detail and examines it, bearing in mind its use as high-power testing equipment.
TL;DR: In this article, an amplitude or power stabilizer has been constructed at the National Bureau of Standards Boulder Laboratories, using the recently developed self-balancing dc bolometer bridge and a commercially available, electrically controlled, ferrite attenuator which achieves power stabilities of a few parts in 10/sup 4/ per hour.
Abstract: Recent developments in the microwave field have provided new tools for use in regulating the output amplitude of a microwave signal source. An amplitude or power stabilizer has been constructed at the National Bureau of Standards Boulder Laboratories, using the recently developed self-balancing dc bolometer bridge and a commercially available, electrically controlled, ferrite attenuator which achieves power stabilities of a few parts in 10/sup 4/ per hour. Use of a high directivity directional coupler permits stabilization of the forward traveling component of the signal, thus providing the equivalent of a matched, stable generator. In practice, a broad-band source match of vswr less than 1.05 is achieved, and this figure may be further improved, at a given frequency, by suitable tuning. In addition, the device has applications as a precision broad-band attenuator, since known changes in power level may be achieved by switching certain of the associated dc components.
Abstract: This paper treats the reflection of linearly and sinusoidally tapered waveguides. In the first part, reflection coefficients of linearly tapered waveguides for dominant modes are calculated. Graphs of the vswr of tapers for different impedance ratios are plotted showing that the vswr does not go to unity at multiples of a half wavelength. In the second part, reflection coefficients of sinusoidally tapered waveguides are calculated. Experimental data verify the theory for both kinds of tapers of various lengths at 4 kmc band. Linear tapers perform almost as well as exponential tapers, and better than shorter hyperbolic tapers. The reflection coefficients of sinusoidal tapers can be about half as small as that of the linear tapers, and these tapers compare favorably with the Dolph-Tchebycheff and the Willis taper of improved design.
TL;DR: In this paper, the effects of dielectric constant and nonlinear geometry on loss, dispersion, and field extent on the image line were examined for an asymmetric line, i.e., the case of a binding medium partially submerged in an image surface.
Abstract: Some further studies on the dielectric image line are presented. Following a verification of field purity for the conventional image system, the effects of dielectric constant and dielectric geometry on loss, dispersion, and field extent are examined. Results are also discussed for an asymmetric line, i.e., the case of dielectric binding medium partially submerged in an image surface.
TL;DR: In this paper, an exact solution for a gyromagnetic rod centered in a right circular cylindrical cavity resonator is given, which is applied in evaluating dielectric and tensor-magnetic measurements on a well-known ferrite.
Abstract: An outline of an exact solution for a gyromagnetic rod centered in a right circular cylindrical cavity resonator is given. This solution is applied in evaluating dielectric and tensor-magnetic measurements on a well-known ferrite. Complex frequencies and constitutive parameters are introduced and the solution is expanded in series to obtain a convenient calculational scheme. Comparisons are made of exact and perturbation calculations of results from a small and a large sample. The effect of insufficient symmetry of the cavity is discussed and the condition for sufficient symmetry is given. The g value of electrons was 2.02.
TL;DR: In this paper, the generalized Manley-Rowe relations for nonlinear anisotropic media with single-valued relations between the instantaneous /bar E/ and /bar P/, and the instantaneous *bar H/ and *bar M/ were generalized to include the power flow in the fields produced in the presence of lossless, nonlinear media.
Abstract: The Manley-Rowe relations, originally derived for nonlinear lumped circuit elements, are generalized to include the power flow in the fields produced in the presence of lossless, nonlinear media. The generalization is carried out first for nonlinear anisotropic media with single-valued relations between the instantaneous /bar E/ and /bar P/, and /bar H/ and /bar M/. The proof is extended to include gyromagnetic media under small-signal excitation at the signal frequency (but large excitation at the pump frequency). The relations are applied to show under what conditions power gain can be achieved with a three-frequency and a four-frequency excitation of a ferrite. The form of the coupling coefficients in the electromagnetic operation of a ferrite amplifier is shown to be a consequence of the generalized Manley-Rowe relations.
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TL;DR: In this paper, a transformer from an unbalanced 50-ohm coaxial line to a balanced pair of 50-ohm coaxial lines is described. But the insertion loss is only 0.5 db over this band of frequencies.
Abstract: Experimental results are given for a transformer from an unbalanced 50-ohm coaxial line to a balanced pair of 50-ohm 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.
TL;DR: In this paper, an experimental investigation of surface wave launching efficiency is described, where wires, rings, and slots are considered as exciters of the HE/sub 11/ mode on a dielectric rod image line.
Abstract: This paper describes an experimental investigation of surface wave launching efficiency. Wires, rings, and slots are considered as exciters of the HE/sub 11/ mode on a dielectric rod image line. A formula is derived which relates the efficiency of a launcher to its impedance as a scatterer on the surface waveguide. Efficiency is obtained by using this formula and also by applying Deschamps' method for determtimg the scattering matrix coefficients of a port junction. Graphs are presented which illustrate the variation of efficiency with the dimensions of the launchers and with the parameter lambda/sub g//lambda, the ratio of the guide wavelength to the free space wavelength.
TL;DR: In this article, the propagation constant of a ferrite-filled microstrip is measured as a function of the longitudinal static magnetic field, and the results agree with the analysis by Van Trier of the infinite parallel plane waveguide filled with gyromagnetic media.
Abstract: The propagation constant of a ferrite-filled microstrip is measured as a function of the longitudinal static magnetic field, The results agree with the analysis by Van Trier of the infinite parallel plane waveguide filled with gyromagnetic media. The analysis is extended to anisotropies greater than 0.5. A simple relationship between propagation constant and anisotropy for the quasi-TEM mode with small spacing (X<
TL;DR: In this paper, the authors describe new microwave techniques employing the properties of N-type germanium diode switches for applications requiring very high isolations, where multiple switches are added in tandem to form antiresonant cavity circuits.
Abstract: This paper describes new microwave techniques employing the properties of N-type germanium diode switches. For applications requiring very high isolations, multiple switches are added in tandem. With proper spacing, they form antiresonant cavity circuits. In this case the isolations and insertion losses in db are directly additive. A switch is described which is normally ON and is pulsed OFF. Finally, details are given of a switch in a hybrid-tee configuration in which switching isolations of 50 db are obtained with an insertion loss of 0.7 db.
TL;DR: In this paper, a theoretical analysis of the excitation of the lowest circular symmetric TM surface wave along an infinite circular dielectric rod by a metallic cylindrical waveguide coaxial with the rod is presented.
Abstract: This paper is a theoretical analysis of the excitation of the lowest circular symmetric TM surface wave along an infinite circular dielectric rod by a metallic cylindrical waveguide coaxial with the rod. The asymptotic expressions for all the fields are obtained by means of the Wiener-Hopf method. The expressions for the total average power transmitted to the surface wave, the total average power reflected, and the total power radiated, per unit incident power, are derived and computed for epsilon=2.49 for various radii of the dielectric rod.
TL;DR: In this paper, an experimental model consisting of a five-channel multiplexer using double-tuned-circular-waveguide directional filters has been constructed, which has a midband insertion loss related to the separation of adjacent channels.
Abstract: The design of microwave multiplexing systems for frequency channelization of a broad-band microwave spectrum is complicated by problems such as off-resonance mismatch and mutual interaction between adjacent filters. By employing directional filters as basic building blocks, it is possible to construct multiplexing filters with a perfect input match since the input VSWR of a directional filter is theoretically unity both at resonance and off-resonance. Less insertion loss of a manifold may be obtained by the use of directional filters than with conventional band-pass filters. Curves giving the predicted response of a manifold containing n elements are presented for single-tuned and double-tuned directional filters. An asymmetrical response shape is obtained which has a midband insertion loss related to the separation of adjacent channels. An experimental model consisting of a five-channel multiplexer has been constructed utilizing double-tuned-circular-waveguide directional filters.
TL;DR: In this article, a theoretical analysis of the resistance sheet isolator is carried out, and numerical solutions are obtained for the forward and reverse propagation constants of the distorted dominant mode in a rectangular waveguide containing a transversely magnetized thick ferrite slab displaced slightly from the side wall.
Abstract: A theoretical analysis of the resistance-sheet isolator is carried out, and numerical solutions are obtained for the forward and reverse propagation constants of the distorted dominant mode in a rectangular waveguide containing a transversely magnetized thick ferrite slab displaced slightly from the side wall. The microwave electric field patterns within the waveguide are plotted for several values of the physical design parameters of the isolator for which experimental performance data have been reported. Field patterns are used to describe the principles of the isolator and to select the optimum values of slab thickness, internal dc magnetic field, ferrite magnetization, and location of the slab in the waveguide for the idealized isolator. Evidence is presented to show that it is necessary to use a comparatively thick ferrite slab located in a very small usable range of distances from the side wall. The appropriate value of internal dc magnetic field is simply related to the magnetization of the ferrite and to the frequency. It has not been necessary to take into account the perturbing effects of the resistance card or matching techniques in order to explain the basic design principles.
TL;DR: In this paper, the presence of losses in the coupling network (between the cavity and the available external terminals) is not justitied, and its use can lead to significant errors.
Abstract: In the use of the impedance (Q-circle) method of measuring the cavity Q values, the presence of losses in the coupling network (between the cavity and the available external terminals) is usually neglected. If appreciable losses are present this simplification is not justitied, and its use can lead to significant errors. The losses in any coupling network can be described by means of an equivalent canonical circuit containing a series and a shunt resistor. The losses due to the series element are immediately apparent from the character of the impedance locus when plotted on a Smith Chart and can be corrected for an "apparent" Q value. However, unless the shunt loss can be determined by a separate calibration of the coupling network, the apparent Q value will be ambiguous because the shunt losses occurring in the coupling network are not distinguishable from those in the cavity proper. Methods for using the impedance data for determining the Q values are given on the assumption that the coupling network parameters cm be found. It is also pointed out that due to the presence of coupling losses the loaded and external Q values are no longer uniquely defined, but their meaning depends upon the application of interest. Formulas relating these to the coupling network parameters are given.
TL;DR: In this article, an approximate analytical solution to the problem of radiation from a ferrite-filled rectangular waveguide is presented, where the vector Huygens' principle is applied to find the far-zone radiation field from the determined aperture field.
Abstract: This paper presents an approximate analytical solution to the problem of radiation from a ferrite-filled rectangular waveguide. The field distribution at the mouth of the guide is assumed to be unaffected by the termination of the guide. The vector Huygens' principle is applied to find the far-zone radiation field from the determined aperture field. The solution to the problem is found in this manner for the cases of longitudinal and transverse magnetization of the ferrite. The transverse magnetization case is supplemented with a discussion of a specfic numerical example which includes plots of the aperture field distribution and the phase angle as well as plots of the far-zone radiation field. The experimentally known phenomenon of the effect of the applied magnetic field upon the shift of the main lobe is demonstrated and verified analytically.
TL;DR: Theoretical and experimental results showed that the line width and g factor of a spherical ferrite sample can be measured in a cross-guide coupler as discussed by the authors, which is much easier to instrument than the usual cavity method.
Abstract: Theoretical and experimental results are presented to show that the line width and the g factor of a spherical ferrite sample can be measured in a cross-guide coupler. The method is much easier to instrument than the usual cavity method and the measurements are much easier to perform. Experimental verification with a cavity perturbation system indicates that the measured quantities are sufficiently accurate for most purposes.
TL;DR: In this paper, the variation of line width (Delta H) and effective g factor (g/sub eff/) with cobalt content and with temperature is studied in a series of ferrites of composition Ni/sub 1- alpha/Co/sub alpha/Mn/sub 0.02/Fe/sub 2-t/Al/sub t/O/sub 4+-/, with alpha varying from 0 to 0.09; temperatures range from 20° to 340° C.
Abstract: The variation of line width (Delta H) and effective g factor (g/sub eff/) with cobalt content and with temperature is studied in a series of ferrites of composition Ni/sub 1- alpha/Co/sub alpha/Mn/sub 0.02/Fe/sub 1.9/O/sub 4+-/. Here alpha lies between 0 and 0.09; temperatures range from 20° to 340° C. A minimum in Delta H is observed at alpha=0.027; g/sub eff/ decreases with increasing alpha. The temperature dependence of each is qualitatively that which would be expected on the basis of the temperature dependence of the anistrophy of the mixed ferrite. Above room temperature Delta H and g/sub eff/ increase or decrease, depending on the cobalt content. It is also shown that the shape of the resonance line is determined by the sign of the anisotropy constant. For negative K/sub 1/ the line is steeper on the low-field side of resonance--for positive K/sub 1/ it is steeper on the high-field side. Resonance data are presented on several nickel-cobalt ferrite-aluminates, of composition Ni/sub 1_alpha/Co/sub alpha/Mn/sub 0.02/Fe/sub 2-t/Al/sub t/O/sub 4+-/, with alpha varying from 0 to 0.025 for t=0.3, 0.4, 0.5, and 0.6. The reduction of Delta H and g/sub eff/ expected from anisotropy considerations is observed.
TL;DR: In this paper, the design of a series of broadband Tchebycheff-type stepped waveguide transformers from various sizes of standard rectangular waveguides to a double ridged waveguide covering the frequency range of 4750 to 11,000 mc is described.
Abstract: The design of a series of broad-band Tchebycheff-type stepped waveguide transformers from various sizes of standard rectangular waveguides to a double ridged waveguide covering the frequency range of 4750 to 11,000 mc is described. Four separate transformers employing RG-67/U (WR-90), RG-68/U (WR-112), RG-106/U (WR-137), and WR-159 to Airtron ARA-133 double-ridged waveguide have been designed using this technique and cast in aluminum. The complete frequency range is covered by several pairs depending on which sizes of mating rectangular waveguides are desired. The RG-106/U design covers a frequency range of 53 per cent with a maximum VSWR of 1.08, while the other three designs each cover a slightly smaller frequency band with a VSWR not exceeding 1.05. Along with the experimental results obtained, an outline of the design method is given which can be used to design similar transformers between any compatible rectangular and double ridged waveguides.
TL;DR: In this paper, the results of an investigation of the use of a microwave crystal as an RF switching element were given. But the authors did not consider the effect of frequency and power on the switching performance.
Abstract: This paper gives the results of an investigation of the use of a microwave crystal as an RF switching element. Variation of a dc bias applied to the crystal will change its impedance, thereby providing an electronic control of microwave power. Empirical data are correlated with the physical structure of the crystal and its equivalent circuit to establish the frequency and power limitations of the switch. A comparison is also made of the switching properties of germanium and silicon crystals. Curves are given for predicting the switching capacity of any diode once its impedance has been normalized with respect to the characteristic impedance of the waveguide. Some methods are suggested for improving the bandwidth and power capacity of the crystal switch.
TL;DR: In this article, the non-reciprocal propagation of electromagnetic waves in ionized gaseous media is discussed and experimental observations are reported, and the classical Faraday experiment in the optics of anisotropic media has suggested an analogous phenomenon at microwave frequencies.
Abstract: The nonreciprocal propagation of electromagnetic waves in ionized gaseous media is discussed, and experimental observations are reported in this paper. The classical Faraday experiment in the optics of anisotropic media has suggested an analogous phenomenon at microwave frequencies. The anisotropic behavior of the free electron gas which is immersed in a magnetic field and subjected to an incident electromagnetic wave is determined. Guided microwave experiments were performed which confirm the theoretical predictions of nonreciprocal wave propagation in such ionized gases.