Showing papers in "IEEE Transactions on Microwave Theory and Techniques in 1993"
TL;DR: In this article, a double-slot antenna placed on hemispherical lenses with varying extension lengths was investigated and the theoretical results were presented in terms of extension-length/radius and radius/ lambda, and therefore result in universal design curves for silicon lenses of different diameters and at different frequencies.
Abstract: Far-field patterns and Gaussian-beam coupling efficiencies are investigated for a double-slot antenna placed on hemispherical lenses with varying extension lengths. The radiation patterns of a double-slot antenna on a silicon dielectric lens are computed using ray-tracing inside the dielectric lens and electric and magnetic field integration on the spherical dielectric surface. The measured radiation patterns at 246 GHz and Gaussian-beam coupling efficiencies show good agreement with theory. The theoretical results are presented in terms of extension-length/radius and radius/ lambda , and therefore result in universal design curves for silicon lenses of different diameters and at different frequencies. The theoretical and experimental results indicate that for single units, there exists a wide range of extension lengths which result in high Gaussian-coupling efficiencies (50-60%) to moderately high f 's. These Gaussian-coupling efficiencies can be increased to 80-90 degrees % with the use of a lambda /sub m//4 matching-cap layer. For imaging array applications with high packing densities, an extension-length/radius of 0.38 to 0.39 (depending on frequency) will result in peak directivity and a corresponding Gaussian-coupling efficiency 15-20% lower than for single units. >
754Â citations
Abstract: A procedure for synthesizing multilayered radar absorbing coatings is presented. Given a predefined set of N/sub m/ available materials with frequency-dependent permittivities in /sub i/(f) and permeabilities mu /sub i/(f) (i=1,. . ., N/sub m/), the technique determines simultaneously the optimal material choice for each layer and its thickness. This optimal choice results in a screen which maximally absorbs TM and TE incident plane waves for a prescribed range of frequencies (f/sub 1/,f/sub 2/,. . ., f/sub N/f) and incident angles ( theta /sub 1/, theta /sub 2/,. . ., theta /sub N theta /). The synthesis technique is based on a genetic algorithm. The technique automatically places an upper bound on the total thickness of the coating, as well as the number of layers contained in it, which greatly simplifies manufacturing. In addition, the thickness or surface mass of the coating can be minimized simultaneously with the reflection coefficient. The algorithm was successfully applied to the synthesis of wideband absorbing coatings in the frequency ranges of 0.2-2 GHz and 2-8 GHz. >
543Â citations
TL;DR: In this paper, the authors present experimental and modeling results for high-Q microwave acoustic resonators and filters for use in oscillators and other frequency control applications, including Ladder filters fabricated with overmoded resonators.
Abstract: The authors present recent experimental and modeling results for high-Q microwave acoustic resonators and filters for use in oscillators and other frequency control applications. Overmoded resonators have exhibited an FQ product greater than 1*10/sup 14/ Hz (e.g., Q=68,000 at 1.6 GHz) with a strong inductive response suitable for one-port and two-port oscillator feedback circuits. Ladder filters fabricated with overmoded resonators have loaded Qs greater than 40,000 with 76-kHz bandwidth at 1.6 GHz. Aluminum nitride films were used for transduction on Z-cut sapphire and lithium niobate substrates. >
349Â citations
TL;DR: In this paper, a quasi-TEM model of MMIC coplanar structures is presented and the elements of the distributed equivalent circuit are calculated by closed-form approximations and hence can be easily implemented into CAD packages.
Abstract: A quasi-TEM model of MMIC coplanar structures is presented. The elements of the distributed equivalent circuit are calculated by closed-form approximations and hence can easily be implemented into CAD packages. The effects of nonideal conductors are included as well as substrate loss and finite metallization thickness. The description holds for the entire quasi-TEM range, i.e. for typical MMIC geometries from DC to millimeter-wave frequencies. The validity of the model was checked by comparison to full-wave results. The errors for the effective dielectric constant and the characteristic impedance range below 5% for the attenuation typical values of 5-10% are found (maximum: 20%). >
324Â citations
TL;DR: In this paper, a method for electronic beam scanning in linear arrays of antenna-coupled oscillators is introduced which eliminates the need for phase shifters, and it is shown that a constant phase progression can be established by slightly detuning the peripheral array elements, while maintaining mutual synchronization.
Abstract: A method for electronic beam scanning in linear arrays of antenna-coupled oscillators is introduced which eliminates the need for phase shifters. It is shown that a constant phase progression can be established by slightly detuning the peripheral array elements, while maintaining mutual synchronization. This unusual nonlinear behavior is explained using coupled Van der Pol equations. A stability analysis provides theoretical limitations on the achievable interelement phase shift. When the phase of the coupling is zero, the theory predicts an interelement phase shift that can be varied continuously over the range -90 degrees > Delta theta >
306Â citations
TL;DR: In this article, a dynamic theory of coupled oscillators is developed and applied to the class of loosely coupled quasi-optical oscillator arrays, which permits the calculation of stable, steady-state phase relationships between the oscillators.
Abstract: A dynamic theory of coupled oscillators is developed and applied to the class of loosely coupled quasi-optical oscillator arrays. This theory permits the calculation of stable, steady-state phase relationships between the oscillators. The distribution of free-running frequencies and the coupling parameters are most important in determining the behavior of the arrays. It is found that free-running frequencies of the peripheral elements have the strongest influence on the steady-state phase relationships. The influence of randomness in the frequency distribution is considered for the case of broadside beamforming, establishing a critical value for the coupling strength in order to maintain mutual synchronization with a specified maximum beam deviation. Techniques for simplifying the calculation of phase relationships for some common coupling parameters are also developed. >
290Â citations
TL;DR: In this article, a new differential equation approach is proposed for general dispersive media for which the complex permittivity in *( omega ) may be described by a single-order Debye relaxation equation or a modified version thereof.
Abstract: A weakness of the finite-difference-time-domain (FDTD) method is that dispersion of the dielectric properties of the scattering/absorbing body is often ignored and frequency-independent properties are generally taken. While this is not a disadvantage for CW or narrowband irradiation, the results thus obtained may be highly erroneous for short pulses where ultrawide bandwidths are involved. In some recent publications, procedures based on a convolution integral describing D(t) in terms of E(t) are given for media for which the complex permittivity in *( omega ) may be described by a single-order Debye relaxation equation or a modified version thereof. Procedures are, however, needed for general dispersive media for which in *( omega ) and mu *( omega ) may be expressible in terms of rational functions, or for human tissues for which multiterm Debye relaxation equations must generally be used. The authors describe a new differential equation approach, which can be used for general dispersive media. In this method D(t) in terms of E(t) by means of a differential equation involving E, and their time derivatives. The method is illustrated for several examples. >
249Â citations
TL;DR: In this article, the authors discuss critical aspects of imaging system design and describe several different imaging systems employing focal plane array receivers operating in the 3mm-2mm wavelength range, including a near-focus system for identification of plastic materials concealed underneath clothing.
Abstract: The authors discuss critical aspects of imaging system design and describe several different imaging systems employing focal plane array receivers operating in the 3-mm-2-mm wavelength range. Recent progress in millimeter-wavelength optics, antennas, receivers and other components permits greatly enhanced system performance in a wide range of applications. A radiometric camera for all-weather autonomous aircraft landing capability and a high sensitivity cryogenically cooled array for use in radio astronomical spectroscopy are presented. A near-focus system for identification of plastic materials concealed underneath clothing employs a two element lens, and has been demonstrated in active (transmitting) and passive (radiometric) modes. A dual-mode imaging system for plasma diagnostics utilizes both active and passive modes at its approximately=140-GHz operating frequency to study small-scale structure. The radiometric imaging systems employ between 15 and 256 Schottky barrier diode mixers, while the imaging receivers for the active systems include 64-element video detector arrays. >
246Â citations
TL;DR: In this article, an investigation study of microwave-optical mixing in different configurations of LiNbO/sub 3/Mach-Zehnder interferometric modulators is presented.
Abstract: An investigation study of microwave-optical mixing in different configurations of LiNbO/sub 3/ Mach-Zehnder interferometric modulators is presented. In each case, models that describe mixer performance are developed and are shown to be in good agreement with measurements. For antenna remoting applications, a technique to down-convert RF signals is demonstrated by cascading in series a pair of Mach-Zehnder interferometric modulators. In general, it is shown that by virtue of their truly broadband characteristics, interferometric modulators can also by employed as microwave mixers at frequencies up to 40 GHz. >
242Â citations
TL;DR: In this article, a wide rectangular radiating slot excited by a microstrip line is described and coupled integral equations are formulated to find the electric current distribution on the feed line and the electric field in the aperture.
Abstract: An analysis of a wide rectangular radiating slot excited by a microstrip line is described Coupled integral equations are formulated to find the electric current distribution on the feed line and the electric field in the aperture The solution is based on the method of moments and using the space domain Sommerfeld-type Green's function The information about the input impedance or reflection coefficient is extracted from the electric current distribution on the microstrip line utilizing the matrix pencil technique The theoretical analysis is described and data are presented and compared with other theoretical and experimental results >
217Â citations
TL;DR: In this paper, different configurations of coupled lines or parallel connected coupled lines can be used together with a uniform transmission line, other coupled lines, or parallel coupled lines in order to obtain a differential phase shifter with loose coupled lines and the same performance as for the standard case.
Abstract: In a standard Schiffman phase shifter a coupled section and a uniform transmission line are used to give a differential phase shift. In order to achieve larger bandwidth it is necessary to use tight coupled sections which are difficult to realize. It is shown how different configurations of coupled lines or parallel connected coupled lines can be used together with a uniform transmission line, other coupled lines, or parallel connected coupled lines in order to obtain a differential phase shifter with loose coupled lines and the same performance as for the standard case. The measurements confirm the calculated results, leading to a more realizable structure. >
TL;DR: In this article, an uniplanar crossover hybrid-ring coupler using a coplanar waveguide (CPW) and slotline provides substantially improved amplitude and phase characteristics over a broad bandwidth compared to conventional microstrip hybrid ring couplers.
Abstract: Novel uniplanar 180 degrees and 190 degrees hybrids suitable for MIC and MMIC applications are described. The uniplanar crossover hybrid-ring coupler using a coplanar waveguide (CPW) and slotline provides substantially improved amplitude and phase characteristics over a broad bandwidth compared to conventional microstrip hybrid-ring couplers. Experimental results show that the new coupler has a bandwidth of more than one octave from 2 GHz to 4 GHz with a +or-0.4-dB power dividing balance and a +or-1 degrees phase balance. A uniplanar two-branch directional coupler using a coupled rectangular slotline ring has also been developed. CPW-to-slotline transitions using uniform and nonuniform CPWs or slotlines are also discussed. These transitions are uniplanar and simple to fabricate. No via-holes are needed for ground connections, and integration with solid-state devices is easy. A pair of broadband transitions using CPW shorts and slotline radial stubs is demonstrated with a 1-dB bandwidth of more than 5.2:1. >
TL;DR: In this article, the authors derived analytical approximations for the conductor losses of asymmetric coplanar waveguides (ACPW) on a finite-thickness dielectric substrate.
Abstract: New analytical approximations are derived for the conductor losses of asymmetric coplanar waveguides (ACPW) and coplanar striplines (ACPS) on a finite-thickness dielectric substrate. The expressions hold for lines whose metallizations have thickness much smaller than the slot and strip widths, but suitably larger than the skin penetration depth at the operating frequency. The derivation is based on an extension of the conformal mapping approach formerly proposed by Owyang and Wu (1958) for symmetric lines in air. Comparisons with published data from quasistatic or full-wave numerical analyses are presented to validate the expressions derived for both the symmetric and the asymmetric case. The analytical characterization presented in the paper is well suited for inclusion into CAD codes for MMIC design. >
TL;DR: In this paper, the Nyquist plots of the n transfer functions completely characterize the number of right-half complex-frequency-plane zeros of det M/sub n/, and hence the amplifier stability.
Abstract: Stability analysis of multidevice amplifiers is made on a generalized circuit comprising two n-ports with S-matrices S (active devices) and S' (passive networks) connected at n interface ports. Open-loop transfer functions defined for a signal-flow graph and its (n-1) subgraphs of incident and reflected waves at the interface ports are expressed in terms of det M/sub n/ and its minors, where M/sub n/=S'S-I/sub n/ and I/sub n/ is the n*n identity matrix. it is shown that the Nyquist plots of the n transfer functions completely characterize the number of right-half complex-frequency-plane zeros of det M/sub n/, and hence the amplifier stability. Insertion of an ideal circulator and isolators at the interface ports enables one to calculate the Nyquist plots and voltage distributions of possible instabilities using commercially available linear circuit simulators. Numerical simulations for two types of parallel-operated GaAs FET amplifiers are performed to verify the usefulness of the analysis in design-phase check of multidevice amplifier stability. >
TL;DR: In this paper, a method for measuring the noise parameters of MESFETs and HEMTs is presented based on the fact that three independent noise parameters are sufficient to fully describe the device noise performance.
Abstract: A method for measuring the noise parameters of MESFETs and HEMTs is presented. It is based on the fact that three independent noise parameters are sufficient to fully describe the device noise performance. It is shown that two noise parameters, R/sub n/ and mod Y/sub OPT/ mod , can be directly obtained from the frequency variation of the noise figure F/sub 50/ corresponding to a 50 Omega generator impedance. By using a theoretical relation between the intrinsic noise sources as additional data, the F/sub 50/ measurement only can provide the four noise parameters. A good agreement with more conventional techniques is obtained. >
TL;DR: In this paper, the authors describe the design and performance of shunt inductively coupled bandpass filters implemented on an open coplanar waveguide, which exhibits low radiation loss due to the removal of the capacitively coupled gaps encountered in end or edge coupled filters.
Abstract: This paper describes the design and performance of shunt inductively coupled bandpass filters implemented on an open coplanar waveguide. This new structure exhibits low radiation loss due to the removal of the capacitively coupled gaps encountered in end or edge coupled filters. Unloaded Qs greater than 540 have been achieved in unshielded single section resonators at 4 GHz on very thin substrates. These high Qs enable the design of filters with low insertion loss and good stopband rejection. Applications include low insertion loss, high and printed filters where no screening is required, low noise oscillators and superconducting filters. >
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TL;DR: In this article, the Gaussian beam-mode treatment of free-space propagation is extended to cover the transformations produced by conic-section reflectors or lenses, and both the propagation steps and the lens transformations are incorporated into a matrix formulation readily applicable to networks of such reflectors.
Abstract: The basis of the near-complete analytical methodology that now exists for the design of long-wave optical systems is set out. The Gaussian beam-mode treatment of free-space propagation is extended to cover the transformations produced by conic-section reflectors or lenses, and both the propagation steps and the lens transformations are incorporated into a matrix formulation readily applicable to networks of such reflectors or lenses. In the process the theorems of Fourier optics are demonstrated and the vectorial properties of the beam-fields are kept explicit. It is shown how recent formulations of partial coherence have made it possible to include partially coherent beams in the same methodology. For the design of high-performance systems, the inclusion of higher-order mode dispersion must be fully understood, the vector properties must be recoverable, and the paraxiality on which the methodology rests must be critically assessed. The authors emphasize these aspects and present a single systematic formulation embracing all the elements. >
TL;DR: In this article, a method for modeling and analyzing vias of multilayered integrated circuits is presented, where the whole via structure is divided into cascaded subnetworks including a vertical via passing through different layers and transitions from the microstrip line and/or striplines to the vertical via.
Abstract: A method for modeling and analyzing vias the multilayered integrated circuits is presented. The model is based on microwave network theory. The whole via structure is divided into cascaded subnetworks, including a vertical via passing through different layers and transitions from the microstrip line and/or striplines to the vertical via. The parameters of each subnetwork are obtained from electromagnetic field analysis. Numerical results in the frequency domain and the time domain are presented. Validation of the model has been carried out by both measurements and finite-difference-time-domain (FDTD) modeling. The results show good agreement with the measurements in the frequency range for which the components of the experimental model are within specification. The time domain simulation results also agree well with the FDTD results. >
TL;DR: In this article, a 10-GHz grid amplifier with a metal grid pattern was designed to provide effective coupling between the heterojunction-bipolar transistors (HBTs) and free space, achieving a peak gain of 10 dB at 10 GHz with a 3-dB bandwidth of 1 GHz.
Abstract: A 100-element 10-GHz grid amplifier has been developed. The active devices in the grid are chips with heterojunction-bipolar-transistor (HBT) differential pairs. The metal grid pattern was empirically designed to provide effective coupling between the HBTs and free space. Two independent measurements, one with focusing lenses and the other without, were used to characterize the grid. In each case, the peak gain was 10 dB at 10 GHz with a 3-dB bandwidth of 1 GHz. The input and output return losses were better than 15 dB at 10 GHz. The maximum output power was 450 mW, and the minimum noise figure was 7 dB. By varying the bias, a signal could be amplitude modulated with a modulation index as large as 0.65. Tests show that the grid was quite tolerant of failures-the output power dropped by only 1 dB when 10% of the inputs were detuned. The grid amplifier is a multimode device that amplifies beams of different shapes and angles. Beams with incidence angles up to 30 degrees were amplified with less than a 3-dB drop in gain. >
TL;DR: In this paper, a finite-width conductor-backed coplanar waveguide (FW-CBCPW) through line is placed within a test fixture commonly used in laboratories, and the scattering parameters of the through line are obtained theoretically by approximating the FW- CBCPW as a simple system of coupled transmission lines.
Abstract: This paper presents theoretical and experimental results for a finite-width conductor-backed coplanar waveguide (FW-CBCPW). The guiding characteristics of FW-CBCPW are investigated first by the rigorous method of mode matching. An FW-CBCPW through line is then placed within a test fixture commonly used in laboratories, and the scattering parameters of the through line are obtained theoretically by approximating the FW-CBCPW as a simple system of coupled transmission lines. Experimental results are shown to agree very well with the theoretical ones. In particular, the anomalous behavior observed in the transmission characteristic of the through line is related to the resonant phenomenon of the terminated side planes which are short-circuited at both input and output ends due to the test fixture. Finally, a technique of mode suppression in the side-plane regions is suggested for the improvement of signal transmission over a broad band of frequency spectrum. The effects of extra higher order modes on the transmission characteristics at high frequencies are also discussed. >
TL;DR: In this article, a hybrid antenna with an integrated superconductor-insulator-superconductor (SIS) detector and a broadband matching structure at submillimeter wavelengths is presented.
Abstract: A dielectric lens antenna that is a special case of an extended hemispherical dielectric lens and is operated in the diffraction-limited regime is considered. The dielectric lens antenna is fed by a planar antenna that is mounted on the flat side of the dielectric lens antenna, using it as a substrate, and the combination is termed a hybrid antenna. Beam pattern and aperture efficiency measurements were made at millimeter and submillimeter wavelengths as a function of the extension of the hemispherical lens and of lens size. An optimum extension distance for which excellent beam patterns and simultaneously high aperture efficiencies can be achieved is found experimentally and numerically. At 115 GHz the aperture efficiency was measured to be (76+or-6)% for a diffraction-limited beam with sidelobes below -17 dB. Results for a single hybrid antenna with an integrated superconductor-insulator-superconductor (SIS) detector and a broadband matching structure at submillimeter wavelengths are presented. The hybrid antenna is space efficient in an array due to its high aperture efficiency, and is easily mass produced, thus being well suited for focal plane heterodyne receiver arrays. >
TL;DR: In this article, the analog performance of an external modulation fiber-optic link was analyzed in terms of the microwave scattering matrices of the modulator and detector circuits, and a modulator bias condition was predicted to promote optimum link performance.
Abstract: We fully analyze the analog performance of an external modulation fiber-optic link. We express relevant figures of merit-including gain, noise figure, third-order intermodulation distortion, AM compression, and dynamic range-in terms of the microwave scattering matrices of the modulator and detector circuits, and we predict the modulator bias condition promoting optimum link performance. Our predictions match the measured gain, noise figure, and dynamic range of an experimental 870-930 MHz external modulation fiber-optic link. Maximum spurious-free dynamic range-77 dB.MHz/sup 2/3/ (117 db.Hz/sup 2/3/)-occurs when the modulator is biased at its halfwave voltage, where the optical throughput is nearly pinched off. >
TL;DR: In this paper, the authors used the mode matching method to accurately model a generalized cylindrical dielectric resonator structure in a rectangular waveguide or cavity, which can be used in filter design as the basic element, providing very good mechanical stability.
Abstract: The mode matching method is used to accurately model a generalized cylindrical dielectric resonator structure in a rectangular waveguide or cavity. The field distributions of different modes in cavities are given. The resonant frequencies of the cavities are calculated and compared to the measured data, showing very good agreement. The resonator structure can be a dielectric disk resonator, a ring resonator, a dielectric resonator with support, etc. This structure can be used in filter design as the basic element, providing very good mechanical stability. The slot coupling between cavities is also analyzed, showing some interesting results. >
TL;DR: In this paper, a wideband T-junction diplexer is presented, which is rigorously modeled using mode matching and a novel two-dimensional curve fitting method.
Abstract: Scattering parameters of E- and H-plane stepped waveguide and E-plane ridge waveguide stepped T-junctions are obtained using an extension of the three-plane mode matching method. An optimization process is applied to find the T-junctions and step dimensions that yield a low reflection coefficient in one of the T-junctions arms over a wide frequency band. An example of the design of a wideband T-junction diplexer is presented. The diplexer filters are inductive window waveguide filters, and are rigorously modeled using mode matching and a novel two-dimensional curve fitting method, which greatly reduces the CPU time for optimization. The diplexer optimization procedure, as well as the filter modeling method, are described. Experimental results on the optimized T-junction and the diplexer are presented; both show excellent agreement with their computed optimum results, without any adjustments or tuning. >
TL;DR: A planar monolithic diode mixer that achieves 5-10dB conversion loss and very low distortion and spurious responses over a 26-40GHz RF and local oscillator (LO) bandwidth and DC-12-GHz IF is described in this paper.
Abstract: A planar monolithic diode mixer that achieves 5-10-dB conversion loss and very low distortion and spurious responses over a 26-40-GHz RF and local oscillator (LO) bandwidth and DC-12-GHz IF is described. Two types of diodes have been used: the first used the gate-to-channel junctions of 0.2- mu m*80- mu m InGaAs HEMTs; and the second used Schottky diodes realized in HBT technology. The baluns are Marchand-like coplanar structures. >
TL;DR: In this paper, a dry composite material composed of microwave ceramic powder, graphite powder, and bonding resin was developed to estimate the specific absorption rate (SAR) of human heads exposed to microwave sources.
Abstract: A dry phantom material having the same electric properties in the UHF band as biological tissues is developed. The new composite material is composed of microwave ceramic powder, graphite powder, and bonding resin. This material overcomes the various problems inherent in the conventional jelly phantom material, such as dehydration and deterioration due to invasion of bacteria or mold. This phantom material makes it possible to accomplish highly reliable and precise estimation of specific absorption rate (SAR) in biological systems. Dry phantom models of spheres and human heads are fabricated. Experiments are performed to estimate the SAR of human heads exposed to microwave sources by using the thermography method. Since this material removes the necessity of the phantom shell, the surface SAR distribution can be readily obtained. >
TL;DR: In this paper, a model based on surface states was proposed to explain this phenomenon, which then led to the use of charge-screen layers and a double-recessed gate process to suppress surface effects.
Abstract: The authors determined that RF drain current degradation is responsible for the poor power performance of wide-recessed pseudomorphic high-electron-mobility transistors (PHEMTs). A model based on surface states was proposed to explain this phenomenon, which then led to the use of charge-screen layers and a double-recessed gate process to suppress surface effects. Combined, these two modifications increased the device's gate-drain reverse breakdown voltage without causing a degradation in the transistor's RF drain current. This allowed the simultaneous achievement of high power-added efficiency and high power density which established a new performance record for power PHEMTs at X- and Ku-bands. Delay time analysis of single- and double-recessed PHEMTs revealed that the benefit of a larger breakdown voltage in the latter device design came at the cost of a larger drain delay time. Drain delay accounted for 45% of the total delay when the 0.35- mu m double-recessed PHEMT was biased at V/sub ds/=6 V. >
TL;DR: In this article, the influence of the algorithm used for noise parameter fitting on the accuracy of the microwave noise parameter measurements is investigated, and five commonly used algorithms are compared by a statistical analysis including instrument accuracy specifications.
Abstract: The influence of the algorithm used for noise parameter fitting on the accuracy of the microwave noise parameter measurements is investigated. Five different commonly used algorithms are compared by a statistical analysis including instrument accuracy specifications. Some of these algorithms are found to be more efficient in terms of available accuracy and computer time. The best predicted available accuracies reported betwen 4 and 20 GHz for each noise parameter compare well with observed accuracies on noise parameter measurements performed with a dedicated test set on a noise standard made of a passive two-port. The accuracy on minimum noise figure is found to be 0.1 dB maximum. >
TL;DR: In this paper, a spectral-domain integral equation formulation is used to analyze the propagation characteristics of open integrated microstrip transmission lines, and the results obtained are compared to the results of other workers, and good agreement is observed.
Abstract: There has been a resurgence of interest in the propagation characteristics of open integrated microstrip transmission lines. This is due in part to the discovery of diverse propagation regimes for higher-order modes on open lines. In contrast to the dominant EH/sub 0/ mode, three distinct propagation regimes exist for higher-order modes on microstrip transmission lines. In this paper, a rigorous spectral-domain integral equation formulation is used to analyze propagation in all three regimes. This formulation provides a clear physical picture of the different propagation regimes based on the mathematical location of poles and branch points in the complex spectral-variable plane. As an illustration, the formulation is applied to the case of an isolated uniform microstrip transmission line. The integral equation is discretized via the method of moments, and entire-domain basis functions incorporating suitable edge behavior are utilized to provide convergence with relatively few terms. The results obtained are compared to the results of other workers, and good agreement is observed. >
TL;DR: In this article, the full-wave mode-matching method for three key building block elements (asymmetric rectangular double-step, asymmetric rectangular tocircular and circular-to-circular waveguide junctions) associated with the generalized S-matrix technique for composite structures is described.
Abstract: The rigorous CAD of a class of rectangular and circular waveguide cavity filters which are coupled by rectangular and/or circular irises is described. The design theory is based on the full-wave mode-matching method for three key building block elements (asymmetric rectangular double-step, asymmetric rectangular-to-circular and circular-to-circular waveguide junctions) associated with the generalized S-matrix technique for composite structures. The waveguide filters may be arbitrarily composed of the key building block elements and the rectangular or circular waveguide sections between them. Finite iris thicknesses, higher-order mode interactions, and asymmetric structures are rigorously taken into account. The theory is verified by measurements. >