# Showing papers in "IEEE Transactions on Microwave Theory and Techniques in 1966"

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TL;DR: In this paper, a method for quantitative comparison of solid-state microwave square-law detectors is presented, where the threshold response of the detectors are compared for unit video bandwidth using the concept of noise equivalent power (NEP).

Abstract: A method for quantitative comparison of solid-state microwave square-law detectors is presented. The threshold response of the square-law detectors are compared for unit video bandwidth using the concept of noise equivalent power (NEP). NEP is the microwave input power required for unity signal-to-noise ratio in a 1 Hz bandwidth at the output of the detector. Contours of constant NEP in the microwave (RF) and video frequency plane clearly describe the dependence of threshold sensitivity on both video and radio frequencies, and thereby provide comparison of the threshold sensitivities of devices over the entire video and RF frequency spectrum. A criterion for the upper RF power lid of square-law operation for detectors is also presented. Dynamic range for a device can be found using this criterion and the threshold sensitivity of the device. Six solid-state detection devices are described briefly, then compared on the basis of the foregoing concepts. Four of these devices are familiar: the point-contact and planar Schottky-barrier ("hot carrier") diodes, and the tunnel and back diodes. Two relatively new devices are also discussed: the so-called "hot carrier" thermoelectric detector, and the space-charge-limited (SCL) dielectric diode.

174 citations

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TL;DR: In this article, the authors analyzed the compensated balun and the parameters which determine its bandwidths, and the practical considerations which preclude realization of infinite bandwidths are pointed out, and experimental verification of the balun theory is presented, along with an application to an S-band impedance-transforming compensated Balun.

Abstract: The compensated balun, first described by Marchand and later reinvented by Roberts, is found to have much broader band-widths than realized by either author. This balun is analyzed here and the parameters which determine its bandwidths are discussed. Curves are presented which allow the design of a balun having any bandwidth. The practical considerations which preclude realization of infinite bandwidths are pointed out. Since the balun is one-quarter wavelength long at center frequency, the balun can be less than one-twentieth wavelength at its lowest operating frequency. Because impedance transformation is generally required with balanced-to-unbalanced line transformation, two techniques including impedance transformation are discused. The reactance slope of the compensated balun is controllable, which allows the balun to directly compensate for the reactance slope of some loads. An example of the compensation of a dipole antenna over a 17-percent bandwidth is discussed. Finally, experimental verification of the balun theory is presented, along with an application to an S-band impedance-transforming compensated balun.

130 citations

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TL;DR: In this article, a two-diode sampler located at the center of a dielectric filled, biconical cavity containing the RF transmission line is introduced into the cavity by applying it directly between the centers of the opposite faces of the cavity.

Abstract: Sampling techniques as used in wideband oscilloscopes have, in the past, yielded bandwidths up to 4000 MHz. This approach has now been employed to achieve bandwidths in excess of 15 GHz. The design requirements necessary for this extended bandwidth are presented along with a detailed description of one solution to the design problem. The device is basically a two-diode sampler located at the center of a dielectric filled, biconical cavity containing the RF transmission line. The RF line is perpendicular to the axis of the biconical cavity. The sampling pulse is introduced into the cavity by applying it directly between the centers of the opposite faces of the cavity. This establishes a potential difference between two points on the ground conductor of the RF transmission line being sampled. This technique is basic to the operation of the device and plays a key role in the reduction of sampling loop inductance, which would limit the bandwidth. The equivalent circuits are presented along with the appropriate defining equations. The relationship between bandwidth, input VSWR, and step response overshoot, are presented, along with the typical measured results.

128 citations

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TL;DR: In this paper, a new class of coupled-transmission-line directional couplers, called nonsymmetrical directional Couplers (NDSDPs), is described.

Abstract: A new class of coupled-transmission-line directional couplers, called "nonsymmetrical directional couplers," is described. Unlike conventional directional couplers, nonsymmetrical directional couplers use coupled lines of unequal characteristic impedances. The principal difference between the performance of nonsymmetrical directional couplers and that of conventional designs is the impedance level of the coupled waves, which may be changed to higher or lower impedance levels than that of the incident wave. These directional couplers may be designed to have infinite directivity and to be matched at all frequencies, or they may be designed to have infinite directivity at all frequencies and a specified maximum VSWR. Coupling relationships and design equations for both cases are presented, and the relative properties of both cases are discussed. The theoretical limitation on the maximum coupling and the maximum impedance transformation that can be obtained simultaneously are derived. Techniques for broadbanding by cascading additional sections of coupled limes are described. Experimental results of a trial --10-dB coupler with coupled lines of 50 and 75 ohms are presented.

109 citations

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TL;DR: In this paper, the authors considered the packaged diode as a radial-line structure and proposed an analytical justification for the incorporation of the diode circuit with the circuits of waveguide, coaxial-line, and strip-line diode mounts.

Abstract: Suitable definitions of the elements in the equivalent circuit of a packaged diode yield a lumped-element circuit with an impedance at its terminals which is the same as the total radial-line impedance of the packaged diode with the outer surface of the diode taken as the terminal surface. Consideration of the packaged diode as a radial-line structure permits an analytical justification for the incorporation of the diode circuit with the circuits of waveguide, coaxial-line, and strip-line diode mounts. As a result, the lumped-element equivalent circuit of a packaged diode can be directly related to the microwave equivalent circuit of the diode and the mount together. Diode element values, which were obtained from low-frequency measurements, have been used in conjunction with the theoretically determined circuits of mounted diodes to predict resonant frequencies at X-band of waveguide, coaxial-line, and stripline mounts holding packaged diodes. Similarly, antiresonant frequencies of greater than 20 Gc/s have been predicted for diodes in a radial cavity. The validity of all these predictions has been verified by measurement.

102 citations

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TL;DR: In this paper, an offset parallel-coupled strip configuration is described, in which the mechanical parameters are strip width, strip offset, and ratio of strip spacing to ground-plane spacing.

Abstract: An offset parallel-coupled strip configuration is described, in which the mechanical parameters are strip width, strip offset, and ratio of strip spacing to ground-plane spacing. The electrical parameters are dielectric constant, characteristic impedance, even and odd mode impedance. The configuration is analyzed by conformal rnapping techniques. Explicit design equations are derived in which the mechanical parameters are expressed in terms of the electrical parameters. Illustrative results are presented, and the limitations on coupling strength, characteristic impedance, and strip configuration are discussed.

102 citations

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TL;DR: In this paper, the authors extend the design data to ridged rectangular waveguides of any aspect ratio and show that the error introduced by proximity effects is of the order of a few percent.

Abstract: Design curves for ridged rectangular waveguides of the usual aspect ratio of 0.45 were published by Hopfer following earlier work carried out by Cohn and Marcuvitz. This paper has been written to extend the design data to ridged rectangular waveguides of any aspect ratio. An analysis of the error introduced by proximity effects has shown these to be of the order of a few percent.

96 citations

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TL;DR: In this article, an approximate synthesis technique for TEM directional couplers and fixed phase shifters consisting of multiple parallel-coupled quarter-wave sections is described without the use of polynomials by a first-order relationship between the components and Chebyshev antenna arrays.

Abstract: An approximate synthesis technique is described for TEM directional couplers and fixed phase shifters consisting of multiple parallel-coupled quarter-wave sections. Synthesis is accomplished without the use of polynomials by a first-order relationship between the components and Chebyshev antenna arrays. The design procedure has the important advantage of allowing the maximum coupling coefficient between transmission lines to be an independent parameter. An iterative correction procedure for bringing the performance arbitrarily close to equal-ripple is described. The process has been programmed for electronic computation, and the results have been tabulated for directional couplers of 3, 6, 10, and 20 dB overall coupling and for phase shifters of 90, 45, and 22.5 degrees differential phase shifts. Bandwidth ratios range between 2 and 25, and the number of coupled sections ranges from 3 to 21 for couplers and from 2 to 9 sections for phase shifters. Maximum normalized even-mode impedance ranges from 1.83434 to 4.5.

92 citations

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79 citations

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TL;DR: In this article, a non-resonant perturbation technique for the measurement of electric and magnetic field strengths within a device is presented, where reflection coefficient measurements are made at the same frequency with, and without, a perturbing object placed at the point at which the field strength is to be measured.

Abstract: This paper presents a theory for a nonresonant perturbation technique for the measurement of electric and magnetic field strengths within a device. Most presently employed perturbation field strength measurements require the use of a resonance technique. In the technique discussed here, reflection coefficient measurements are made at the same frequency with, and without, a perturbing object placed at the point at which the field strength is to be measured. By these data, and by the equations derived and presented in this paper, the desired field strength can be calculated. The technique can be used for cavities that are too lossy to support resonance, and is suitable for cavities for which the resonant field configuration differs from the field configuration to be measured. In addition, this technique has the advantage that it permits the measurement of the phase, as well as the amplitude of the field.

77 citations

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TL;DR: In this paper, the authors describe impedance transforming networks which consist of short lengths of relatively high impedance transmission line alternating with short length of relatively low impedance line, and the lengths of the line sections are typically short compared to a quarter wavelength throughout the operating band of the transformer.

Abstract: Impedance transforming networks are described which consist of short lengths of relatively high impedance transmission line alternating with short lengths of relatively low impedance line. The sections of transmission line are all exactly the same length (except for corrections for fringing capacitances), and the lengths of the line sections are typically short compared to a quarter wavelength throughout the operating band of the transformer. Tables of designs are presented which give exactly Chebyshev transmission characteristics between resistive terminations having ratios ranging from 1.5 to 10, and for fractional bandwidths ranging from 0.10 to 1.20. These impedance-transforming networks should have application where very compact transmission-line or dielectric-layer impedance transformers are desired.

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TL;DR: In this article, an analysis of cascaded commensurate transmission-line C-section all-pass networks is presented, and the analytical form of the transmission coefficient is found to have a very simple form, intimately related to the reflection coefficient of the stepped-impedance transformer prototype of the cascaded Csection.

Abstract: An analysis of cascaded commensurate transmission-line C-section all-pass networks is presented. The analytical form of the transmission coefficient is found to have a very simple form, intimately related to the reflection coefficient of the stepped-impedance transformer prototype of the cascaded C-section. The phase function of cascaded commensurate transmission-line C-sections is investigated and found to be the arctangent of a reactance function in tan /spl theta/. Last, general, exact synthesis procedures for designing cascaded commensurate transmission-line C-section all-pass networks to have prescribed phase characteristics are presented, and two design examples are given. One of the examples is the exact design of a 3-section Schiffman 90/spl deg/ phase shifter, which has not been previously reported in the literature.

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TL;DR: In this article, two precise measurement techniques are described that eliminate the effect of air gaps through the use of resonant modes, for which E/sub n/=0 at the dielectric-to-metal interface.

Abstract: A particularly severe source of error in the microwave measurement of high dielectric constants has been the presence of small air gaps between dielectric surfaces and metal walls. In this paper, two precise measurement techniques are described that eliminate the effect of air gaps through the use of resonant modes, for which E/sub n/=0 at the dielectric-to-metal interface. In one method a cylindrical sample is resonated within a closely fitting circular waveguide, and in the other a cylindrical sample is placed at the center of a radial waveguide. Both methods utilize a circular-electric-mode whose electric field is parallel to the metal walls. The waveguides are dimensioned to be cut off in their air regions at the resonant frequency of the dielectric sample. Formulas yield /spl epsi//sub r/ as a function of the resonant frequency, and of diameter and length of the dielectric cylinder. Measured data on samples having /spl epsi//sub r/ /spl ap/ 85 show the two methods to agree within a few tenths of one percent. The accuracy of the methods is on the order of 0.5 percent maximum error and 0.2 percent probable error when /spl int//sub 0/ is measured within 0.1 percent and D and L within 0.0005 inch (for D/spl ap/ 0.3 inch and L /spl ap/0.1 inch).

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TL;DR: This paper presents the transient analysis of certain four-port TEM mode microwave networks by analyzing three often used microwave networks and an estimate is made of their "settling times" for a step modulated input.

Abstract: This paper presents the transient analysis of certain four-port TEM mode microwave networks. Flow graph techniques are employed to determine in closed form the system function between two given ports. This representation reveals the pole-zero pattern of the component which is used to graphically obtain the amplitude spectrum (CW response). In the time domain, the impulse response (the inverse transform of the system function) is used to determine the step modulated response of the network at its resonant frequency. This proves to be a particularly easy task for certain symmetrical networks. The flow graph technique is illustrated by analyzing three often used microwave networks (namely; the ring hybrid, the 3-dB branch line coupler, and the branch line phase shifter), and an estimate is made of their "settling times" for a step modulated input. Experimental methods are introduced which permit an investigator to generate a 0.2 nanosecond pulse and/or a microwave step modulated source. These test functions are then used to critically evaluate the theoretical results in the laboratory.

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TL;DR: In this paper, the resonant frequencies for the fundamental modes in circular cylindrical and rectangular parallelopiped high dielectric resonators have been calculated by computer for a range of values of physical dimensions and relative Dielectric constant.

Abstract: The resonant frequencies for the fundamental modes in circular cylindrical and rectangular parallelopiped high dielectric resonators have been calculated by computer for a range of values of physical dimensions and relative dielectric constant. The frequency range extends from zero to 50 kMc/s, the relative dielectric constant from 50 to 1800, and physical dimensions from zero to 500 roils. Results are presented in graphical form with frequency plotted vs. resonator length for parametric values of relative dielectric constant and cross-sectional dimensions. A brief review of earlier work with high dielectric resonators is included. Expressions for the resonant frequency and fundamental mode field configurations are given.

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TL;DR: In this paper, the point-matching method was adopted to solve the boundary value problem for the uniform cylindrical waveguide formed by placing one conductor inside a conducting tube.

Abstract: This paper discusses the uniform cylindrical waveguide formed by placing one conductor inside a conducting tube. Because of the complexity of the guide's cross section, the numerical technique of the point-matching method is adopted to solve the boundary-value problem. The formulations are carried out for the case when each of the conductors has an arbitrary cross section and also for the case when one of the conductors has a circular cross section. The coaxial waveguide modes, in which the field components have angular variations, split into odd and even modes when the center conductor begins to shift axis to form the uniform eccentric waveguide. However, only even modes in the eccentric guide correspond to the coaxial modes with no angular variations. The dependence of the cutoff frequency on the eccentricity of the guide is determined numerically for even and odd TE and TM modes. Experimental results verify the theoretical calculations for TE modes.

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TL;DR: In this article, the authors describe a coupler design employing a continuously tapered coupling coefficient that helps to circumvent the directivity problem in symmetrical couplers. But, the physical junctions between the various sections contribute reactive discontinuities, which significantly degrade coupler directivity.

Abstract: It is possible, at present, to obtain multioctave bandwidth in symmetrical couplers that employ cascaded quarter-wave-length sections of uniformly coupled line. However, the physical junctions between the various sections contribute reactive discontinuities, which significantly degrade coupler directivity. This paper describes a coupler design employing a continuously tapered coupling coefficient that helps to circumvent the directivity problem. Two classes of couplers have been investigated, including one which provides optimum equal-ripple performance. Synthesis has been performed with the aid of both digital and fourier integral computers. Somewhat tighter center coupling is required in the tapered design to produce bandwidth-mean-coupling-level performance comparable to stepped-coupling design. Experimental data is presented on several models constructed in three-layer polyolefin stripline.

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TL;DR: In this article, an exact analysis of the electrical behavior of the shielded coupled strip transmission line with three center conductors is presented, and design formulas which enable one to evaluate the cross-section dimensions from the desired values of characteristic immittances are derived for the two kinds of the line configurations.

Abstract: An exact analysis is made for the shielded coupled strip transmission line with three center conductors. By means of the immittance matrices presented, the electrical behavior of the coupled strip transmission line of this type may be completely described. Design formulas which enable one to evaluate the cross-section dimensions from the desired values of characteristic immittances are derived for the two kinds of the line configurations. Equivalent circuits of the two-port networks for various port conditions are also presented. In addition, an application is discussed involving the asymmetrical coupled strip transmission line with two center conductors. The appendix gives the derivation of the design formulas by means of conformal mapping techniques.

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TL;DR: In this article, a synthesis procedure for distributed elliptic function filters utilizing published tables of lumped-constant elliptic-function filters has been devised, which is dependent upon the application of a new generalized transformation for distributed networks.

Abstract: A synthesis procedure for distributed elliptic-function filters utilizing published tables of lumped-constant elliptic-function filters has been devised. It is dependent upon the application of a new generalized transformation for distributed networks. The filters often require the realization of distributed Brune sections, and several novel practical realizations are given both for general and degenerate Brune (i.e., Foster) sections. Examples are given of elliptic function stop band and pass band filters having both wide and narrow bandwidths, and experimental results show good agreement with theory.

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TL;DR: A theoretical analysis and a unifying classification of methods of measuring phase at UHF and microwave frequencies are presented in this article, where the coherent phase bridge circuits are analyzed in terms of the type of modulation applied to the channels of the bridge and the types of combiner and mixer employed at the output of the beamforming.

Abstract: A theoretical analysis and a unifying classification of methods of measuring phase at UHF and microwave frequencies are presented. The coherent phase bridge circuits are analyzed in terms of the type of modulation applied to the channels of the bridge and the type of combiner and mixer employed at the output of the bridge. In this analysis and classification, identifying characteristics, and some of the relative advantages and disadvantages of these circuits become obvious.

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TL;DR: In this paper, an anomalous burning glow discharge in He or Ne is described, and the responsivity and the noise equivalent power of the device are discussed, where the same tube can be used both for detection of 4 and 2 mm waves by simply raising the applied dc potential a few volts.

Abstract: Detection of 4 and 2 millimeter waves by a small, low-pressure, anomalous burning glow discharge in He or Ne is described. The responsivity and the noise equivalent power are discussed. Typical values are presented in a table: the former is found to be about 50 V/W, the latter about 5 /spl mu/W. The device is linear over about 30 dB, it has a LF bandwidth of about 50 kc/s and the same tube can be used both for detection of 4 and 2 mm waves by simply raising the applied dc potential a few volts. Since the device is very rugged it can withstand a high local oscillator power, so that in a synchronous detection circuit the noise equivalent power can be about 10/sup -11/ W at 1 c/s bandwidth.

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TL;DR: In this paper, the static capacitance matrix of a parallel coupled line array was used to give a simple physical interpretation to familiar transmission line identities and can also be applied to the design of many TEM microwave devices.

Abstract: An important aspect of TEM quarter-wave network synthesis and design is the multiplicity of physical configurations that give identical response characteristics. Different network configurations are often, required to realize the same basic response for moderate changes in design parameters because of the small range of realizable impedance values. In most design procedures, practical circuit element values are obtained by application of suitable equivalent circuit relationships. In a previous paper a systematic method of obtaining equivalent circuits using transformations of the static capacitance matrix of a parallel coupled line array was introduced and applied to the exact design of interdigital bandpass filters. These transformations can also be used to give a simple physical interpretation to familiar transmission line identities and can be applied to the design of many TEM microwave devices.

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TL;DR: In this paper, the authors derived the electromagnetic fields inside a waveguide for both rectangular and cylindrical waveguides, and showed that the cutoff phenomenon is modified in an interesting way when the medium inside the waveguide is moving.

Abstract: This paper treats the propagation of electromagnetic waves in the interior of a waveguide that is filled with a moving medium. The medium is assumed to be homogeneous, isotropic, and lossless, and to move with a constant velocity along the axis of the waveguide. The Maxwell-Minkowski equations for the electromagnetic fields are solved by means of a pair of vector potential functions similar to those frequently used for stationary media. The fields inside the waveguide are derived for both rectangular and cylindrical waveguides. The well-known cutoff phenomenon for a waveguide is found to be modified in an interesting way when the medium inside the waveguide is moving The results show that for a slowly moving medium (a medium for which n/sp, Beta/<1, where n is the index of refraction and /spl Beta/ is the velocity of the medium divided by the velocity of light in vacuum/, there are two critical frequencies, separating three frequency ranges in each of which there is a different type of propogation. For a high-speed medium (n/spl Beta/<1), it is found that there is no cutoff phenomenon at all, although there is one critical frequency separating two frequency ranges in which the propagation is different.

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General Electric

^{1}TL;DR: In this article, the propagation of TE/sub no/ modes in rectangular waveguides that contain two dielectric slabs parallel to the narrow wall and extending over the full height of the guide is investigated.

Abstract: The propagation of TE/sub no/ modes in rectangular wave-guides that contain two dielectric slabs parallel to the narrow wall and extending over the full height of the guide is investigated. Waveguide and dielectric are assumed to be lossless and infinitely long. Apart from these restrictions, the dielectric slabs may have arbitrary thickness, position, and dielectric constant. The analysis is restricted to TE/sub no/ modes with the E-field parallel to the narrow guidewall. The guide containing only one dielectric slab is covered by this analysis. The even modes n = 2, 4, 6, . . . of the guide with two slabs correspond to the odd modes n' = n/2 = 1, 2, 3, . . . of the guide with one slab half the width of the guide with two slabs. For six relative dielectric constants (/spl epsilon/= 2.25, 4.00, 9.00, 12.25, 16.00, 25.00) the cutoff frequencies for TE 10, 20, 30, 40, 60 modes and the normalized propagation constants for TE 10 and TE 20 modes between their respective cutoff frequencies and a frequency slightly above the second- and fourth-order mode cutoff frequency for the empty guide, respectively, have been computed for a large range of slab thicknesses and slab positions. Selected results are presented graphically. These results are discussed. The parametric dependence of field distributions, of normalized characteristic impedances, of the ratio of cutoff frequencies (fractional bandwidth), and of the ratio of magnetic field components (ellipticity) are illustrated.

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TL;DR: In this article, the authors describe the use of dielectric supports with extremely small interface discontinuities, contacting members that are insensitive to mechanical tolerances, calculable airline impedance standards of very high absolute accuracy, nearly reflectionless terminations based on a cylindrical metal-film resistor and adaptors between line sizes based on smooth (rather than stepped) diametral transitions.

Abstract: Significant advances in the performance of precision coaxial standards and components have resulted from rigid adherence to three basic design principles: 1) incremental constancy of characteristic impedance, 2) coplanar compensation of discontinuities, and 3) control of mechanical tolerance sensitivity. The advances include dielectric supports with extremely small interface discontinuities, contacting members that are insensitive to mechanical tolerances, calculable airline impedance standards of very high absolute accuracy, nearly reflectionless terminations based on a cylindrical metal-film resistor, and adaptors between line sizes based on smooth (rather than stepped) diametral transitions. Extensions of the design principles have resulted in the introduction of closely controlled reflections provided by a novel impedance-matching tuner, broadband calibrated mismatches, and resistance-standard terminations that retain their nominal dc values to very high frequencies.

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TL;DR: In this article, the Herpin equivalent index (HERI) was used to replace image admittance in the transmission line theory of dielectric layers of alternating low and high Dielectric constant.

Abstract: Dielectric layers of alternating low and high dielectric constant are useful as filters in the millimeter wave, infrared, and optical regions, spanning a spectrum of about five decades. Transmission line theory can be applied, with refractive index replacing admittance. The electrical or optical thicknesses of the layers are generally integral multiples of the thinnest layer, but the reflection in the pass band can be appreciably reduced by small adjustments in the layer thicknesses. The theory is based on the concept of Herpin equivalent index, which is the optical counterpart of image admittance used by electrical engineers. The theory is reviewed and design data is presented.