Showing papers on "Microstrip published in 1984"

Broad-band microstrip antennas using additional resonators gap-coupled to the radiating edges

Abstract: A method for increasing the bandwidth of microstrip patch antennas by incorporating two additional resonators which are gap-coupled to the radiating edges of a rectangular patch is described. A two-dimensional analysis using Green's function and segmentation method is used for analyzing the proposed antenna configurations. A bandwidth as large as five times a single rectangular patch is obtained in S -band. Changes in the radiation pattern over this wide bandwidth are discussed. Experimental results are in reasonable agreement with the analysis.

Accurate Wide-Range Design Equations for the Frequency-Dependent Characteristic of Parallel Coupled Microstrip Lines

Abstract: In this paper, closed-form expressions are presented which model the frequency-dependent even- and odd-mode characteristics of parallel coupled microstrip lines with hitherto unattained accuracy and range of validity. They include the effective dielectric constants, the characteristic impedances using the power-current formulation, as well as the open-end equivalent lengths for the two fundamental modes on coupled microstrip. The formulas are accurate into the millimeter-wave region. They are based on an extensive set of accurate numerical data which were generated by a rigorous spectral-domain hybrid-mode approach and are believed to represent a substantial improvement compared to the state-of-the-art and with respect to the computer-aided design of coupled microstrip filters, directional couplers, and related components.

Analysis of an infinite array of rectangular microstrip patches with idealized probe feeds

Abstract: A solution is presented for the problem of an infinite array of microstrip patches fed with short current elements. The input reflection coefficient is calculated versus scan angle in an arbitrary scan plane, and the effects of substrate parameters and grid spacings are considered. The scan blindness phenomenom is observed and discussed in terms of a forced surface wave response. Measurements from waveguide simulators confirm the theory for thin substrates.

Accurate transmission-line model for the rectangular microstrip antenna

Abstract: An accurate and numerically efficient model for the rectangular microstrip antenna is presented. It concerns a transmission-line model which features the following three major improvements with respect to earlier such models: the mutual radiative coupling (both real and imaginary parts) between the equivalent slots is fully taken into account; the influence of the side slots on the radiation conductance is taken into account implicitly; simple analytic expressions are introduced for all relevant model parameters. By way of illustration, the new model is applied to antennas with a single microstrip feed line. Excellent agreement is shown with available experimental and theoretical results for the input impedance of a rectangular antenna. The improvements with respect to previous transmission-line models are illustrated for a square antenna.

On the modeling of electromagnetically coupled microstrip antennas--The printed strip dipole

Abstract: A generalized solution for a class of printed circuit antennas excited by a strip transmission line is presented. The strip transmission line may be embedded inside or printed on the substrate. As an example, microstrip dipoles electromagnetically coupled (Parasitically excited) to embedded strip transmission line have been analyzed accurately, and design graphs are provided for a specific substrate material. These graphs permit the establishment of a design procedure which yields the microstrip dipole length, overlap, offset, and substrate thickness with the goal of a desired input match for a given substrate material. The method accounts for conductor thickness and for arbitrary substrate parameter. Comparison with experiment shows excellent agreement.

A History of Microwave Filter Research, Design, and Development

Abstract: An account of the development of microwave filters is surveyed, commencing from 1937. Much of the foundation of modem filter theory and practice took place during the period of World War II and the years immediately following, especially by such pioneers as the late P. I. Richards, whose subsequent career is briefly described. Filter topics discussed include low-pass, bandpass, high-pass, and multiplexers constructed in a variety of media such as waveguide, coaxial line, microstrip, and stripline, as well as dielectric resonators. All types of filter characteristics are surveyed, such as Chebyshev, elliptic and pseudo-elliptic function, Achieser-Zolotarev, and a variety of generalized designs, including linear phase.

Hybrid-Mode Analysis of Arbitrarily Shaped Planar Microwave Structures by the Method of Lines

Abstract: This paper presents a method for analyzing arbitrarily shaped planar microwave structures, which is based on the method of lines and applies to both resonant and periodic structures in microstrip, slotline, and finline circuits. Numerical results are presented for some selected structures.

Planar Circuit Analysis of Microstrip Radial Stub

Abstract: Microstrip radial line stubs are analyzed using a planar circuit technique and characterized for design purposes. Experiments performed on various structures are in excellent agreement with the theory.

Reactively steered adaptive array using microstrip patch elements at 4 GHz

Abstract: A reactively steered adaptive array (RESAA) has one element connected by a transmission line to a receiver and a number of closely spaced parasitic elements, each of which is terminated by an adjustable reactive load. The pattern is formed by control of the reactive loads. Experimental results and the theory are presented for a RESAA consisting of five microstrip rectangular patch elements resonant at 4.0 GHz. Using steepest descent control of the reactive loads in a power inversion mode (no reference), we find that a null with a depth of 30 dB (relative to the pattern maximum) and an angular width of about 25\deg can be steered towards an interferer. Typically, about 40 steps (iterations) are needed for forming the null. With the slow power meter and general purpose minicomputer that served as the controller, adaptation times of several seconds are required; extrapolation to a dedicated microprocessor controller predicts adaptation times of several milliseconds. Operation in a mode using a reference signal demonstrates that the pattern can be shaped to steer a null toward interference and a lobe towards a desired signal. The nulling bandwidth is approximately 40 MHz with this array. The advantages of a RESAA, as compared With a conventional adaptive array, include the elimination of the mixers and other hardware needed to perform the complex weighting of the output of each element at an intermediate frequency, and better pattern control for closely spaced elements. These advantages are obtained at the expense of a more complicated control algorithm.

Planar Circuit Analysis of Microstrip Radial Stub (Short Paper)

Abstract: Radial-line stubs have been found to work better than low-impedance rectangular stubs when an accurate localization of a zero-point impedance is needed. In this paper, microstrip radial-line stubs are analyzed using a planar circuit technique and characterized for design purposes. Experiments performed on various structures are in excellent agreement with the theory and confirm the suitability of such a structure as an altenative to a conventional straight stub.

A theoretical and experimental investigation of annular, annular sector, and circular sector microstrip antennas

Abstract: An analysis is presented for three related shapes of microstrip antenna elements: the annular; annular sector; and circular sector. The method of analysis involves the full expansion of resonant modes within the cavity formed by the radiating patch and the ground plane. Experimental results for representative radiators are also included for comparison.

Subpicosecond Electro-Optic Sampling Using Coplanar Strip Transmission Lines

Abstract: A sampling technique using the electro-optic effect capable of characterizing subpicosecond electrical signals has recently been demonstrated. In this system 100 fs pulses from a colliding pulse mode-locked laser were used to generate the electrical test signal via a Cr:GaAs photoconductive switch. A second beam of pulses was used to probe the birefringence induced by the electrical pulses as they propagate down a balanced stripline fabricated on LiTa03. Signal averaging allowed submillivolt signals to be recovered. The best temporal response of the system was achieved with the velocity matched geometry, which was obtained for a particular angle of incidence of the probe beam on the electro-optic crystal. In this configuration a risetime of 500 fs was obtained. During this work it was observed that strong dispersion effects were taking place when the wavelength of the electromagnetic signal approached the cross-sectional dimensions of the transmission line. Temporal resolution is improved and dispersion effects are reduced as the dimensions of the stripline are reduced. In order to further improve the temporal response of the sampler in this configuration, the thickness would have to be reduced to the order of 10 um, which presents severe fabrication difficulties.

High speed testing of electronic circuits by electro-optic sampling

Abstract: Non-contact measurement of signals up to and beyond 100 GHz is provided by electro-optical sampling the field in a transmission line. A first laser signal is employed to optically generate signals in a III-V compound semiconductor such as gallium arsenide. The signal is transmitted to microstrip on the semiconductor surface, and a second polarized laser signal is passed through the crystal and its polarization is modulated by the electric field in the microstrip. The polarization presents a measure of the field strength and hence the signal. By varying the relative delay between two beams, an equivalent time representation of the sampled signal is obtained.

Planar high-frequency antenna having a network of fully suspended-substrate microstrip transmission lines

Abstract: A planar high-frequency antenna having radiating elements for high-frequency signals includes at least two facing conductive plates provided with oppositely-arranged openings which cooperate to form respective cavities. Disposed between each pair of facing plates is a thin dielectric sheet supporting an array of strip conductors of coaxial lines forming suspended-substrate microstrip lines with these plates. Ends of the strip conductors extend into the cavities and form radiating elements. Each thin dielectric sheet is held in place between the facing plates by means of positioning spacers provided on the faces of these plates. The spacers are located in areas where there are no conductors on the dielectric sheet and are sufficiently remote from each other such that at least two cavities and/or lines of the network of strip conductors are located between any two spacers.

Analysis of Crosstalk in Very High-Speed LSI/VLSI's Using a Coupled Multiconductor MIS Microstrip Line Model

Abstract: Crosstalk in very high-speed LSI/VLSI's is analyzed using a coupled multiconductor metal-insulator-semiconductor (MIS) microstrip line model Loss in the substrate is ignored for simplicity A periodic boundary condition is used, and the mode analysis is done using the Green's function method Effects of line length spacing, substrate thickness, and output impedance of gates are investigated The "lumped capacitance" approximation for interconnections is shown to be inadequate for crosstalk evaluation when the circuit speed is less than 200-300 ps in LSI circuits The result indicates that crosstalk considerations based on a transmission-line model is very important in the design of very high-speed LSI/VLSI circuits, Provisions of adjacent shield lines are shown to be significantly effective in reducing crosstalk but at the risk of dynamic ringing and at the sacrifice of wiring capacity A shielded multilevel interconnect scheme is proposed for reduction of crosstalk without reduction of wiring capacity

Broadband circular polarization arrangement for microstrip array antenna

Abstract: The invention relates to a circular polarization (CP) technique and a microstrip array antenna implementing this technique. Using four microstrip radiating elements with proper phasing of the excitation in a 2×2 array configuration, the technique averages out the cross-polarized component of the radiation, generating circular polarization of high purity. The technique is broadband and capable of dual-polarized operation. The resultant 2×2 array can be used either independently as a CP radiator or as the building subarray for a larger array.

Computer analysis method for arbitrarily shaped microstrip antenna with multiterminals

Abstract: An analysis method is presented for an arbitrarily shaped microstrip antenna with multiterminals. The method is based on the variational method and the modal-expansion technique. Eigenvalues and eigenfunctions are determined using the Rayleigh-Ritz method. Input impedance and other antenna parameters are derived at nonresonance. Furthermore, the network model, useful for the network analysis of a microstrip antenna with multiterminals, is presented by introducing an ideal transformer. Finally, numerical examples are compared with experimental results. The agreement is quite good, and the validity of the present method is confirmed.

A Composite, Multilayered Cylindrical Dielectric Resonator

Abstract: The analysis of TE modes in a composite multilayered cylindrical dielectric resonator is presented. All cylindrical dielectric resonator structures which have found some practical applications can be treated as a special case of the structure under consideration. These include: single resonator, double resonator, ring resonator, resonator in microstrip, inhomogeneous resonator and others. A new rigorous method of determining the field distribution and resonant frequency of this resonator is presented. By this method the solution is obtained in a form of successive approximations converging to an exact solution. The analysis is applied in detail to the lowest frequency TE mode of double dielectric resonator.

Radiation characteristics of higher-order modes in microstrip ring antenna

Abstract: The results of the theoretical analysis of modal fields and radiation characteristics of the microstrip ring antenna are presented. Radiation patterns for the different modes are derived from the fringing fields at the inner and outer peripheries of the ring. Theoretical patterns are compared with experimental results at 1.8 GHz. The analyses show that the TM 1m -modes (m = 2, 4, 6,...) are suitable for broadband boresight antennas while TM 1m -modes (m = 1,3,...) may be used for narrowband boresight antennas.

On the Solution of a Microstripline with Two Dielectrics

Abstract: We present the calculation for, the capacitance and the effective dielectric constant for a microstripline with two different dielectrics. The solution is based on the exact transformation law provided by two successive Schwarz-Christoffel transformations, which is given in terms of the Jacobi Z/sub n/ function. This function can be easily separated into its real and imaginary parts, allowing the exact determination of the curve which separates the two dielectrics in the transformed plane. Once the curve is obtained, the capacitance of the system is calculated numerically by a finite-difference method. We compare our results with data obtained from Wheeler's approximate ellipse solution, as well as with other analytical solutions. We assume an infinitely wide ground plane and TEM-mode propagation.

Microstrip disk antennas, Part II: The problem of surface wave radiation by dielectric truncation

Abstract: The far zone fields radiated from a microstrip disk antenna with a truncated dielectric layer were obtained using the cavity model with magnetic side walls, the dyadic Green's functions are stratified media, and the integral representation analysis of the fields in the complex plane. It is shown that the truncation of the dielectric is responsible for the ondulations observed in the radiation patterns of these antennas and that they result from the interference of the space wave fields with those radiated as a consequence of the incidence of the surface wave into the truncation region. It is suggested that this interference problem may be alleviated by truncating the dielectric as far as possible from the antenna elements and by using lower values of dielectric thickness to disk radius ratios d/a , and of dielectric relative permittivities \epsilon_{r} .

Microstrip antenna system with fixed beam steering for rotating projectile radar system

Abstract: A microstrip antenna system has a central two-dimensional array (preferably square having at least 16×16 elements) of integrally formed conductive dual slot microstrip radiator patches. A corporate-structured array of interconnected microstrip feedlines connects a common input/output r.f. signal feedpoint to each of the central array patches and also incorporates a fixed-angle phasing offset so as to steer the main lobe or beam of the overall radiation pattern off-center. The common r.f. signal input/output connection point is itself physically offset to one side of the overall composite of array elements. Auxiliary tapered amplitude linear arrays of dual slot patches also preferably extend on all sides outwardly from the periphery of the central array so as to reduce the side lobe amplitude and main lobe beamwidth of the overall radiation pattern. Both series-fed and series-tapped tapered amplitude feedlines are used depending upon whether the auxiliary linear array extends in the E-plane direction or the H-plane direction. The fixed phasing offset is preferably in the H-plane direction of the overall central array. Pairs of broad-banding microstrip stubs may be disposed along the corporate structure feedline in association with predetermined subsets of dual slot patches within the central array so as to increase the frequency bandwidth over which impedance matched signal feeding is achieved.

An Analysis of a Width-Modulated Microstrip Periodic Structure

Abstract: The wave propagation along a microstripline with sinusoidally varying width has been investigated. The analysis employs the circuit theory of uniform microstriplines and their step junctions. The wave amplitude transmission (WAT) matrix has been successfully used to determine the propagation constant, characteristic impedance, and the input impedance of the terminated line. Samples have been fabricated for the experimental verification of the above-mentioned quantities. Theory and experiment show good agreement.

The Microstrip Open-Ring Resonator

Abstract: The open-ring microstrip resonator is analyzed by utilizing the two-dimensional magnetic wall model. The solution and the numerical results for the eigenvalues and the electromagnetic fields for various resonant modes are presented. It is shown that the experimental results are in good agreement with the theoretical predictions based on this model.

Nested microstrip arrays

Abstract: An antenna structure in which two or more microstrip arrays are disposed onop of each other to minimize the required space. The shape of the microstrip elements and the polarization thereof are chosen so that the individual elements radiate only in specific areas along the edges of the elements with the remainder of the element having no appreciable electric field concentration. Because of the operating frequency of a microstrip element is a function of the size of the element, a second antenna of smaller higher-frequency elements may be disposed over a larger lower-frequency antenna such that the higher frequency antenna does not cover the areas of the lower antenna that radiate but lies over only those areas having no appreciable electric fields concentrations. Increasingly higher-frequency antennas can be placed on top of the lower-frequency antennas if the foregoing conditions are maintained with respect to all of the covered antennas. This arrangement permits separate feed networks and omnidirectional coverage or directional coverage for each of the arrays independent of the others.

Printed circuit board maximizing areas for component utilization

Abstract: A multilayer printed circuit board for TTL logic components provides an approximate 100 ohm characteristic impedance between external microstrip signal lines and internal ground and voltage planes The addition of two internal microstrip signal plane lines permits a much greater interconnectability capability and also saves a large percentage of spatial area for component mounting while still maintaining the 100 ohm impedance characteristic

Horn antenna and mixer construction for microwave radar detectors

Abstract: A horn antenna construction, particularly for use in microwave radar detector circuits, comprises a molded horn element that is open at its bottom side, with a ridge molded into its flared top surface, and being electrically conductive at least at microwave frequencies such as in the X-band and K-band. The open bottom of the horn element mates to a conductive upper surface on a mounting board, and the horn is drawn down onto the mounting board so that its upper surface forms the bottom of the horn. Thus, the ridge is brought into physical and electrical contact with a feed strip formed in a microstrip board on the mounting board, that has a mixing diode or diodes associated therewith. By this construction, there is a positive and dimensionally stable association of the throat of the horn and the ridge to the feed strip and the mixing diode(s), without the necessity of any solder, inserted connectors or mounting pins, or the provision of any tuning posts or screws. Moreover, very efficient energy conversion, and thereby increased sensitivity, is assured because the horn, the feed strip and certain matching and terminating stubs on the microstrip board assure good isolation between the mixing ports and low energy loss at the mixer.

Microstrip disk antennas, Part I: Efficiency of space wave launching

Abstract: A theoretical study on the problem of surface wave excitation of microstrip disk antennas is presented. The cavity model with magnetic sidewalls and dyadic Green's functions in stratified media is used to obtain the radiated fields in an integral form. Lossless media are assumed such that there is no cross coupling between the powers in the space ( P_{SP} ) and surface ( P_{SU} ) waves. The separate contributions of these two powers is examined. With the assumption that P_{SU} does not contribute to the main radiation patterns of the antenna an efficiency of space wave launching and a corresponding antenna directivity are defined. Values of efficiency and directivity as functions of the dimensions of the antenna and for two values of dielectric constants of the substrate are shown. Agreement of these results with some of the available data is observed. It is worth noting that P_{SU} may correspond to an appreciable portion of the total radiated power.

Method of incrementally adjusting the center frequency of a microstrip-line printed filter by manuevering dielectric layers

Abstract: A method is provided for adjusting the electrical characteristics and particularly the frequency of a microstrip-line printed filter with distributed constants. The method consists in depositing a strip of dielectric material on all the microstrip resonators of the filter.