Showing papers on "Microstrip published in 1994"

Space mapping technique for electromagnetic optimization

Abstract: We offer space mapping (SM), a fundamental new theory to circuit optimization utilizing a parameter space transformation. This technique is demonstrated by the optimization of a microstrip structure for which a convenient analytical/empirical model is assumed to be unavailable. For illustration, we focus upon a three-section microstrip impedance transformer and a double folded stub microstrip filter and explore various design characteristics utilizing an electromagnetic (EM) field simulator. We propose two distinct EM models: coarse for fast computations, and the corresponding fine for a few more accurate and well-targeted simulations. The coarse model, useful when circuit-theoretic models are not readily available, permits rapid exploration of different starting points, solution robustness, local minima, parameter sensitivities, yield-driven design and other design characteristics within a practical time frame. The computationally intensive fine model is used to verify the space-mapped designs obtained exploiting the coarse model, as well as in the SM process itself. >

Phased array antenna system including a coplanar waveguide feed arrangement

Abstract: The disclosure relates to a phased array antenna for microwave and millimeter wave applications, using either microstrip line, coplanar waveguide, or other construction techniques incorporating a solid dielectric transmission line. A continuously variable phase delay structure which is used to control the beam pattern of the phased array antenna can be applied to the construction of resonant frequency tunable coplanar waveguide antennas and impedance tunable quarter-wave transformers. A thin film of barium strontium titanate (Bax Sr1-x TiO3) or other nonlinear material such as PbZrx Ti1-x O3 (PZT), LiNbO3, etc. is deposited upon the coplanar waveguide, and/or the patch antenna element. The dielectric constant of the thin film can be made to vary significantly by applying a DC voltage to the thin film. The propagation constant of a transmission line is directly proportional to the square root of the effective dielectric constant (assuming a lossless dielectric). In an array of multiple antenna elements provided with the feed structure using the disclosed transmission lines, the direction of the resultant main beam of the array can be made to vary over a complete half-sphere with only two adjustable DC voltages applied to the dielectric thin films.

Microstrip to waveguide transition compatible with MM-wave integrated circuits

Abstract: Microstrip to waveguide transitions used presently typically require a relatively complex waveguide mount extending on both sides of the planar circuit. Additionally, the planar substrate has to be cut into specific forms limiting the flexibility of the planar circuit design and complexity. In this paper, a new type of transition is described based on the principle of slot coupled antennas radiating into the waveguide. In this way, the extension of the planar circuit is not restricted, and at the same time, the involved antenna element can be used to hermetically seal the microwave/MM-wave input. >

Multilayer microstrip wiring board with a semiconductor device mounted thereon via bumps

Abstract: A semiconductor device includes a microstrip wiring board. The microstrip wiring board includes a substrate having a main surface, a ground conductor extending on the main surface of the substrate, a dielectric film extending on the ground conductor, and a metal wiring line extending on the dielectric film. A semiconductor chip is connected to the microstrip wiring board via a bump.

Study of the capacitively fed microstrip antenna element

Abstract: The moment method is used to solve the integral equations describing the capacitively fed rectangular microstrip antenna element. This element consists of a ground plane, a radiating patch, and a small patch located between ground plane and radiating patch. The small patch is fed by a coaxial probe. It excites the radiating patch through capacitive coupling. After checking the accuracy by comparing calculated and measured results, the effect of the capacitor patch is analyzed theoretically. A procedure is given to determine capacitor patches which yield elements matched to the coaxial feed. It is shown how a matched configuration can be found for a given capacitor patch height. >

Analysis and design of microstrip-to-waveguide transitions

Abstract: A wide band, low insertion loss transition from shielded microstrip line to rectangular waveguide is analyzed by the mode matching method and the cascading procedure using generalized scattering matrices. The transition consists of a discontinuity between a ridge waveguide and the microstrip line and a ridge waveguide impedance transformer. The microstrip eigennodes, including complex modes, are obtained by mode matching method with LSE and LSM mode expansion. The element values of the equivalent circuit for a ridge waveguide step junction is determined from its S-parameters. Computed results of a 17-22 GHz transition agree well with available experimental results. This rigorous approach provides a useful tool for the optimum design of microstrip to air filled waveguide or dielectric filled waveguide transitions. >

Characterization of high frequency interconnects using finite difference time domain and finite element methods

Abstract: MIC and MMIC packages capable of good performance at frequencies as high as 60 GHz need to have small volume, low weight, microstrip and/or coplanar waveguide (CPW) compatibility and exhibit negligible electrical interference with the rest of the circuit. In order to acquire some of these characteristics, special provisions need to be made during circuit layout and design, resulting in high-density packages. The designed circuits have a large number of interconnects which are printed on electrically small surface areas and communicate through the substrate in a direct through-via fashion or electromagnetically through appropriately etched apertures. In a circuit environment of this complexity, parasitic effects such as radiation and cross talk are intensified, thus, making the vertical interconnection problem very critical. In this paper, transitions using through-substrate vias are considered and analyzed both in the time and frequency domains using the Finite Difference Time Domain (FDTD) technique and the Finite Element Method (FEM), respectively. The merits of each method in conjunction with accuracy, computational efficiency and versatility are discussed and results are compared showing excellent agreement. Specifically, a microstrip short-circuit, a microstrip ground pad, a CPW-to-microstrip through-via transition and a channelized CPW-to-microstrip transition are analyzed and their electrical performance is studied. >

The electromagnetic field of a vertical electric dipole in the presence of a three‐layered region

Abstract: The electromagnetic field generated by a vertical electric dipole in the air over the surface of a two-layered region is determined for continuous-wave excitation. The region of interest consists of a conductor or dielectric with high permittivity, coated with an electrically thin layer of a dielectric under a half-space of air. Simple explicit formulas are derived for the field at all points in all three regions including the surface wave. Typical applications are to microstrip circuits and antennas, communication over the earth when this is coated with a layer of asphalt or cement, and communication over the sea or a lake when this is under a layer of ice.

Crosstalk between microstrip transmission lines

Abstract: Methods for prediction of crosstalk between microstrip transmission lines are reviewed and simplified for the weak-coupling case. Classical coupled transmission line theory is used for uniform lines, and potential and induced EMF methods are used for crosstalk between nonuniform lines. It is shown that the potential method is equivalent to classical coupled transmission line theory for the case of uniform lines. An experiment was performed for uniform coupled microstrip lines for frequencies from 50 MHz to 5 GHz, and good agreement between theory and measurement was obtained for both near- and far-end crosstalk. >

New stacked microstrip antenna with large bandwidth and high gain

Abstract: A new radiating element is presented, which can provide simultaneously a large bandwidth and high gain. It consists of four identical patches uniformly displayed within a rectangular aperture (2*2) and fed electromagnetically by a driven patch etched on a lower substrate. It is shown that a good coupling with the parasitic patches is obtained, causing a large bandwidth, and the resonance modes of each patch are excited in phase, giving a high gain.

Two-dimensional quasi-optical power-combining arrays using strongly coupled oscillators

Abstract: Two-dimensional quasi-optical power-combining arrays are designed by using strongly coupled oscillators. The oscillators are connected by a microstrip coupling line for strong coupling. Two types of connections are discussed. One is the line-structure and the other is the loop-structure. The oscillation modes of the coupled oscillators for these two types of configurations are analyzed and compared. The experimental results for circuits with different configurations are compared to the theoretical results. The application of these two types of connections in the two-dimensional array is discussed. A multilayer (3-D) structure is employed in the circuit design to accommodate the complex layout of the two-dimensional arrays. A 4/spl times/4 power-combining array in multilayer structure is demonstrated. >

Closed-form formulas for frequency-dependent resistance and inductance per unit length of microstrip and strip transmission lines

Abstract: Based on numerical results obtained from solutions to integral equations, other numerical results and theoretical considerations, a set of closed-form formulas is presented for approximate calculation of frequency-dependent resistance and inductance per unit length of microstrip and strip transmission lines. Extensive verifications reveal that the accuracy obtained by these closed-form formulas is better than 10% for a wide range of parameters. >

A microstrip device for the broad band simultaneous measurement of complex permeability and permittivity

Abstract: The method presented here aims at determining the complex permeability /spl mu/* and permittivity of /spl epsiv/* with an automatic and broad band (45 MHz-18 GHz) system from the reflection-transmission measurement of the S-parameters of a microstrip test device. The complex values /spl epsiv/* and /spl mu/* are obtained with the S-parameters from a specific software created within the context of this work. Compared with previous methods, our measurement technique is fast, easy to implement and does not require any calibration test sample or pick-up coils. Lastly, an analysis of the error depending on the method used and the results found with bulk isotropic materials (dielectrics and ferrites) are presented. >

HF filter design and computer simulation

Abstract: A book for engineers who design and build filters of all types, including lumped element, coaxial, helical, dielectric resonator, stripline and microstrip types A thorough review of classic and modern filter design techniques, containing extensive practical design information of passband characteristics, topologies and transformations, component effects and matching An excellent text for the design and construction of microstrip filters

Microstrip filter design using direct EM field simulation

Abstract: For the first time, we present minimax filter design with electromagnetic (EM) simulations driven directly by a gradient-based optimizer. Challenges of efficiency, discretization of geometrical dimensions, and continuity of optimization variables are overcome by a three-stage attack: 1) efficient on-line response interpolation with respect to geometrical dimensions of microstrip structures simulated with fixed grid sizes; 2) smooth and accurate gradient evaluation for use in conjunction with the proposed interpolation; and 3) storing the results of expensive EM simulations in a dynamically updated database. Simulation of a lowpass microstrip filter illustrates the conventional use of EM simulation for design validation. Design optimization of a double folded stub bandstop filter and of a millimeter-wave 26-40 GHz interdigital capacitor bandpass microstrip filter illustrates the new technique. >

High TC superconducting monolithic ferroelectric junable b and pass filter

Abstract: The design of a high Tc superconducting band pass tunable ferroelectric filter (TFF) is presented. The band pass TFF consists of an edge coupled filter on a ferroelectric substrate. Each input and output microstrip line is a quarter wavelength long. Each intermediate microstrip line is a half wavelength long with the first quarter wavelength being coupled to the preceding microstrip line and the remaining quarter wavelength being coupled to the succeeding microstrip line. Each microstrip line is connected, through an LC filter, to a common bias voltage source. Application of a bias voltage changes the frequency of operation of the filter. For matching the impedances of the input and output of the filter to the impedances of an input and output circuit respectively, matching ferroelectric quarter wavelength transformers are provided.

Improvement of microstrip patch antenna radiation patterns

Abstract: Microstrip patch antennas typically have radiation patterns containing unwanted sidelobes or local minima caused by surface waves, especially when fabricated on high dielectric-constant substrates. The paper shows that removal of the substrate beneath the patch can greatly improve the pattern. A variation of this technique, compatible with monolithic fabrication, is applied to fabrication of a patch on GaAs and shows similar pattern improvement. >

A rigorous study of microstrip crossovers and their possible improvements

Abstract: A theoretical study of microstrip crossovers is presented. For an air-bridge interconnect in a crossover configuration, the equivalent circuit examined exhibits low-pass filter characteristics. To reduce the return loss in the passband, insertion of discrete shunt capacitors is proposed and investigated. These shunt capacitors are treated as linear lumped elements and connected by via-holes of rectangular cross section. It is emphasized that air-bridges, via-holes and lumped elements used in this particular application are all rigorously included in a full-wave spectral-domain analysis. >

Capacitance computations in a multilayered dielectric medium using closed-form spatial Green's functions

Abstract: An efficient method to compute the 2-D and 3-D capacitance matrices of multiconductor interconnects in a multilayered dielectric medium is presented. The method is based on an integral equation approach and assumes the quasi-static condition. It is applicable to conductors of arbitrary polygonal shape embedded in a multilayered dielectric medium with possible ground planes on the top or bottom of the dielectric layers. The computation time required to evaluate the space-domain Green's function for the multilayered medium, which involves an infinite summation, has been greatly reduced by obtaining a closed-form expression, which is derived by approximating the Green's function using a finite number of images in the spectral domain. Then the corresponding space-domain Green's functions are obtained using the proper closed-form integrations. In both 2-D and 3-D cases, the unknown surface charge density is represented by pulse basis functions, and the delta testing function (point matching) is used to solve the integral equation. The elements of the resulting matrix are computed using the closed-form formulation, avoiding any numerical integration. The presented method is compared with other published results and showed good agreement. Finally, the equivalent microstrip crossover capacitance is computed to illustrate the use of a combination of 2-D and 3-D Green's functions. >

Infinite phased arrays of cavity-backed patches

Abstract: An analysis of the radiation properties of infinite phased arrays of probe-fed circular microstrip patches backed by circular cavities using a rigorous Green's function/Galerkin's method is presented. The effect of substrate thickness on both scan volume and bandwidth performance is considered. Results are compared to those of infinite arrays of conventional probe-fed circular patch antennas. >

A dual polarized circular patch rectifying antenna at 2.45 GHz for microwave power conversion and detection

Abstract: A novel circular patch rectifying antenna (rectenna) has been developed which converts microwave energy into DC power at 2.45 GHz. Dual polarization is achieved by two orthogonal microstrip feed lines. Rectification is achieved by GaAs Schottky-barrier diodes located on each feed line. A 48% conversion efficiency from microwave power to DC power was achieved. The design was based on a nonlinear circuit analysis. >

Analysis of a dual circularly polarized microstrip antenna fed by crossed slots

Abstract: A dual circularly polarized, wideband microstrip antenna fed by two perpendicular crossed slots is analyzed in this work. The cross shaped aperture in the ground plane provides coupling between the microstrip patch and a single microstrip line underneath the ground plane, traversing the four arms of the cross in a serial manner, thereby generating four coupling points in phase quadratures for both senses of circular polarization. The analysis of this antenna incorporates two stages: In the first one, the individual load impedances are computed via an integral equation based on reciprocity, assuming no interactions between the ports. The second stage employs a transmission line model where the four coupling points are considered as lumped loads along the feed line. An iterative scheme employs the transmission line model for the determination of the actual impedances of each coupling point, including the mutual interactions with the other coupling points. This procedure provides control over the overall level of radiated energy; hence it can be used in the design procedure of this antenna as a serial or parallel fed array element. The computed results agree very well with measurements. The antenna attains a -3 dB gain bandwidth of 13% to 15%, a 3-dB axial ratio bandwidth of 48%, and -15 dB return loss bandwidth of 60%. >

Approximate model for microstrip fed slot antennas

Abstract: An approximate model developed to obtain the input impedance of the microstrip fed slot antenna is presented. Using this model, the input impedances of several slot antennas are predicted. For these antennas, the validity of the modelling is supported by comparing the values of the return losses measured against those obtained theoretically.

Finite element analysis of MMIC structures and electronic packages using absorbing boundary conditions

Abstract: In this paper, a three-dimensional finite element method (FEM) is employed in conjunction with first and second-order absorbing boundary conditions (ABC's) to analyze waveguide discontinuities and to derive their scattering parameters While the application of FEM for the analysis of MMIC structures is not new, to the best of the knowledge of the authors the technique for mesh truncation for microstrip lines using the first and higher-order ABC's, described in this paper, has not been reported elsewhere The scattering parameters of a microstrip discontinuity are computed in two steps As a first step, the field distribution of the fundamental mode in a uniform microstrip is obtained by exciting the uniform line with the quasi-static transverse electric field, letting it propagate, and then extracting the dominant mode pattern after the higher order modes have decayed In step two, the discontinuity problem is solved by exciting the structure by using the fundamental mode obtained in step one The scattering parameters based on the voltage definition are calculated by using the line integral of electric fields underneath the strip Numerical solutions for several waveguide discontinuities and electronic packages are obtained and compared with the published data >

Traveling wave electro‐optic phase modulator using cross‐linked nonlinear optical polymer

Abstract: We report the fabrication and characterization of a high frequency traveling wave electro‐optic phase modulator made from thermally cross‐linked polyurethane‐Disperse Red 19 polymers. The device has been fabricated using a three layer structure with an integrated 50 Ω microstrip line circuit. The straight channel optical waveguides were defined laterally by standard photolithography and oxygen reactive ion etching. The measured half‐wave voltage was in good agreement with that extrapolated from the second harmonic generation measurements. Optical modulation was observed directly on a spectrum analyzer up to 18 GHz. Long‐term evaluation over an extensive length of time found no observable loss of performance.

A Rigorous Study of Microstrip Crossovers and their Possible Improvements

Abstract: A theoretical study of microstrip crossovers is presented. For an air-bridge interconnect in a crossover configuration, the equivalent circnit examined exhibits low-pass filter characteristics. To rednce the return loss in the passband, insertion of discrete shunt capacitors is proposed and investigated. These shunt capacitors are treated as linear lumped elements and connected by via-holes of rectangular cross section. It is emphasized that air-bridges, via-holes and lumped elements used in this particular application are all rigorously included in a full-wave spectral-domain analysis.

Monolithic quadrifilar helix antenna

Abstract: A quadrifilar helix antenna containing a hybrid junction power divider feed circuit and a plurality of radiating elements. The radiating elements are connected on one end to the hybrid junction power divider feed circuit and are free to radiate on the other end. In a particular embodiment, the antenna includes a microstrip hybrid junction power divider feed circuit deposited on the lower rectangular section of a dielectric substrate. The hybrid junction power divider feed circuit provides both a 0 to 180 degree phase shift and impedance matching. The antenna also includes four radiating microstrip elements deposited on the upper section of the dielectric substrate at a predetermined angle to form a helical pattern upon turning the planar antenna into a cylinder. The radiating elements are connected to the microstrip hybrid junction power divider feed circuit in pairs. The first pair is connected to the hybrid junction power divider feed circuit at the location of the 0 degree phase shift whereas the other pair is located at the 180 degree phase shift location. The second element of each pair is shorter than the first element by a predetermined distance to provide a phase quadrature between them. Therefore through this method, the required phase relationships for a circularly polarized beam pattern are achieved.

Dielectric cover effect on rectangular microstrip antenna array

Abstract: A theoretical model to analyze a covered rectangular antenna with an arbitrary dielectric constant superstrate is developed. The antenna is simulated by the radiation of two magnetic dipoles located at the radiating edges of the patch. The Green's function of an elementary magnetic dipole in a superstrate-substrate structure, utilizing spectral-domain analysis, is formulated, and the surface-wave and radiation field are computed. An improved transmission line model, which considers the stored energy near the radiating edges and the external mutual coupling, is used to compute the input impedances and radiation efficiency. Design considerations on the superstrate thickness and its dielectric constant are discussed. Experimental data for a single element and a 4/spl times/4 microstrip array is presented to validate the theory. >

Microstrip patch antenna array

Abstract: A microstrip patch antenna array incorporating a plurality of spaced-apart patch radiating elements electromagnetically coupled to a microstrip line conductively coupled to a source of signals. Both the spaced-apart patch radiating elements and the microstrip line are located on the same side of an adjacent conductive substrate. The microstrip patch radiating elements are arranged in a linear co-planar array electromagnetically excited by the field created by the air substrated microstrip line passing adjacent thereto.

Microstrip DC-to-GHZ field stacking balun

Abstract: A wideband (DC to GHz) PC-board Balun that is disclosed. The balun mainta low insertion loss and good balance for ultra wide band (UWB) applications such as impulse radar. The balun structure is formed by microstrip transmission lines on a dielectric substrate, having at least one inverting and one non-inverting transmission lines. The transmission lines are connected to form balanced transmission lines stacked about a ground plane. N transmission lines can be connected to form a N 2 :1 impedance ratio balun. Ferrite cores placed about the transmission lines and resistor-capacitor circuits improve the low frequency operation of the balun.