Abstract: The letter presents experimental results for a proximity-coupled microstrip patch antenna capable of 13% bandwidth. The impedance match (VSWR ≤ 2), copolarised radiation patterns and crosspolarised radiation were measured over this bandwidth to confirm operation. The construction is quite simple, consisting of a microstrip feedline on a substrate proximity-coupled to a rectangular microstrip patch on a covering superstrate; a small open-circuit tuning stub is connected in shunt with the feed line.

Abstract: Some confusion in the literature is clarified regarding the properties of microstrip-line higher modes in the neighborhood of cutoff. It is shown that those modes become leaky in that range; with the aid of the steepest-descent plane, one finds that the continuous spectrum can be characterized in a highly convergent manner by essentially a single leaky mode. The leakage occurs in two forms: a surface wave and a space wave. For structures without a top cover, it is found that almost all of the leakage is in the form of a space wave, so that an efficient leaky-wave antenna of particularly simple configuration may be designed that consists of just a length of uniform microstrip line fed in its first higher mode. An accurate leaky-wave analysis is developed that explains quantitatively the performance features and the limitations of this class of antennas.

Abstract: A Galerkin analysis of microstrip circuits of arbitrary planar geometry enclosed in a rectangular conducting box is described. The technique entails a time-harmonic electromagnetic analysis evaluating all fields and surface currents. This analysis is suitable for the accurate verification of microstrip designs prior to fabrication. A computer program implementing the analysis has been written in Pascal on a personal computer. Agreement with measurements of several microstrip structures suggests a high degree of accuracy.

Abstract: In thick microstrip patches, probe inductance prevents matching of the patch impedance to the input connector. The probe inductance can be tuned out with a capacitive gap. To maintain simplified construction the gap is here etched on the patch surface. Bandwidths equal to or greater than that theoretically predicted are realised. Use of a single probe-compensated feed results in radiation pattern distortion, high crosspolarisation and low efficiency due both to higher-order modes and surface-wave generation. Two-probe feeding is used here to overcome these problems and to give a wide-band antenna with good radiation pattern control and high efficiency.

Abstract: A new method for radiating dual or circular polarisation with a printed circuit antenna element is described. A square microstrip patch on one substrate is coupled to a pair of microstriplines on another substrate via two orthogonal, rectangular apertures in a common ground plane. Quadrature excitation of the system results in circularly polarised radiation.

Abstract: A solution to the problem of plane wave scattering by a rectangular microstrip patch on a grounded dielectric substrate is presented. The model does not include the microstrip feed, and thus does not include the so-called "antenna mode" component of the scattering. The solution begins by formulating an electric field integral equation for the surface current density on the microstrip patch. The integral equation is solved using the method of moments. Computed data for the patch radar cross section (RCS) is found to be in close agreement with measurements over a broad frequency range. The microstrip RCS versus frequency consists of a number of large peaks which are identified as impedance or pattern factor resonance peaks.

Abstract: A microstrip to dielectric waveguide transition is provided comprising a gth of rectangular dielectric waveguide which has one end tapered in such a manner that the height of the waveguide top surface above the waveguide bottom surface decreases linearly from full height to zero height at the tapered end of the length of waveguide. The bottom surface of the waveguide length is mounted on the top surface of a planar microstrip dielectric substrate having an electrically conductive metallic ground plane on the bottom substrate surface and a length of microstrip conductor on the top substrate surface aligned with the waveguide length and abutting the tapered end of the waveguide length. A second length of microstrip conductor is mounted on the tapered portion and part of the untapered portion of the top surface of the waveguide length and is electrically connected to the first microstrip conductor at the tapered end of the waveguide length. The dielectric constant of the microstrip substrate should be no greater than the dielectric constant of the dielectric waveguide length and preferably should be much less.

Abstract: A rigorous solution to the problem of a rectangular microstrip antenna fed by a microstripline is presented. The currents on the feed line and the patch are expanded in a suitable set of modes, and a moment method solution is formulated in the spectral domain. Three special feed cases are treated: a patch fed at a radiating edge; a patch fed at a nonradiating edge; and a proximity coupled patch. Good results are obtained for the radiating edge fed case and the proximity coupled case. The nonradiating edge fed case results were not as good; reasons for this discrepancy are discussed. Calculations are compared with measurements for high and low dielectric constant substrates.

Abstract: Equivalent circuits have been derived for microstrip ring and varactor-tuned ring resonators. It was found that the resonant frequency is slightly lower as the coupling gap becomes smaller. Varactor-tuned ring resonators have been developed with up to 15 percent tuning bandwidth using packaged varactor diodes. A dielectrically loaded microstrip ring circuit with lower loss was demonstrated. The results should have many applications in electronically tunable oscillators and filters in both hybrid and monolithic integrated circuits.

Abstract: A compact, easy to manufacture quarter-wavelength microstrip element especially suited for use as a mobile radio antenna has performance which is equal to or better than conventional quarter wavelength whip-type mobile radio antennas. The antenna is not visible to a passerby observer when installed, since it is literally part of the vehicle. The microstrip radiating element is conformal to a passenger vehicle, and may, for example, be mounted under a plastic roof between the roof and the headliner.

Abstract: A compact, easy to manufacture quarter-wavelength microstrip element especially suited for use as a mobile radio antenna has performance which is equal to or better than conventional quarter wavelength whip-type mobile radio antennas. The antenna is not visible to a passerby observer when installed, since it is literally part of the vehicle. The microstrip radiating element is conformal to a passenger vehicle, and may, for example, be mounted under a plastic roof between the roof and the headliner.

Abstract: The common forms of microstrip hybrids are either "backward couplers" formed using parallel lines, or branch-line or rat-race hybrids. All of these tend to have degraded performance due to discontinuities, junction effects, or unequal even- and odd-mode velocities. In contrast, coupled-line microstrip forward couplers do not require any discontinuities or junctions and utilize the unequal mode velocities. As a result, forward couplers can tolerate unusually thick substrates and still achieve high directivity and very little radiation. Though they are relatively long, designs with sizable coupling gaps have reasonable lengths for many applications, particularly at millimeter-wave frequencies. A trial symmetrical design yielded a bandwidth of 15 percent for l-dB maximum unbalance. By use of asymmetrical design, a bandwidth of 57 percent was achieved for the same tolerance. Either quadrature or "magic-T" hybrid performance can be approximated. Directivities of 37 dB or more were readily achieved.

Abstract: From the Publisher: All topics have been updated to present the latest information available in this fast-changing field, and completely new sections have been added to cover the following important topics: AM envelopes produced by complex nonsinusoidal signals Quadrature Amplitude Modulation Noise limiters and blankers Alternate signal-to-noise measurements Single-sideband suppressed carrier and frequency division multiplexing Double-sideband suppressed carrier and quadrature multiplexing Microstrip and stripline Light sources, optical power, optical sources, and link budget Trellis encoding CCIt modem recommendations PCM line speed Extended superframe format and wavelength division multiplexing Kepler's laws Clark orbits, and limits of visibility In addition, an entirely new chapter has been added with coverage of: Mobile telephone systems (including AMPS, PSC, and PCSS) This text is written for use in undergraduate level electronic communications courses in which students have prior knowledge of some of the basic electronic principles, as well as an understanding of mathematics through the fundamental concepts of calculus.

Abstract: In this article, quasi-static and dynamic solutions are derived for microstrip transmission lines on circularly symmetric cylindrical substrates. Novel numerical techniques have evolved which lead to very efficient algorithms. The model is applicable to substrates of arbitrary thickness and cylinder size. Furthermore, it has been checked against a variety of limiting cases, including microstrip on a flat substrate, and it has been found to provide results with excellent accuracy. The analytical extraction of the quasi-static behavior from the dynamic Green's function introduces considerable simplicity in developing the algorithm.

Abstract: A microstrip probe blade which has a ceramic body (20) with a microstrip (26) on one side and a metalized ground plane (30) on the other. A straight needle (32) having a tapered end and a spherical tip is attached to the microstrip axially and protrudes from the body parallel to the microstrip such that a high frequency signal may be conducted through the device with a minimum of electrical aberations. With this blade test, frequencies as high as 10 gigahertz may be achieved overcoming previous frequency limitations. The probe blade by virtue of the ground plane (30) wrapping around slightly to the microstrip side of the body (20) allows the addition of resistors (36) or chip capacitors (38) to minimize electrical spikes, transients, and unwanted opscillations to power supply frequencies.

Abstract: A low-profile patch radiator for use in an array antenna has a multilayer structure which includes a double-tuned impedance matching network and balun and a coaxial feed for linear polarization of the radiated waves. A second embodiment further includes a second double-tuned impedance matching network and balun and a second coaxial feed for dual polarization operation. The matching networks/baluns, which comprise microstrip circuits on Duroid substrates, increase the frequency bandwidth of the patch radiator.

Abstract: The paper presents an equilateraltriangular microstrip antenna (MSA) that can produce circularly polarised waves with a single feed. Theoretically predicted results, such as the operating frequency and feed location with which good circularly polarised radiation can be obtained, are compared with experimentally obtained results. The calculations for the axial ratio and the radiation pattern are also compared with the measurements. For all of the results the agreement is found to be quite good, and it is confirmed that a singly fed equilateral-triangular MSA can produce two kinds of good circularly polarised waves at two different frequencies.

Abstract: A broadband, contiguous stacked, two-layer, square microstrip patch antenna element design is described which can be used for linear or circular polarization. Single layer microstrip patch theory for the rectangular patch radiator is presented and used as a basis for understanding the two-layer patch configuration. The theory is modified to predict radiation patterns and resonant frequencies of the two-layer microstrip patch antenna element. Experimental results include the radiation patterns, dominant resonant frequencies (TM1 0 mode), return loss (S11 ), and bandwidth for X band elements as a function of dielectric constants, dielectric thicknesses, and patch sizes.

Abstract: The cross-polarization level of circular and rectangular patches is evaluated by finding the peak value angles. The peak value is strongly dependent on substrate dielectric constant, varying roughly as 1/\epsilon . Aspect ratio of a rectangular patch has little effect on peak values or location. Patch thickness also has little effect; results are limited to thin patches as surface waves are not included.

Abstract: An algebraic formulation for the resonant frequency of a rectangular microstrip antenna has been derived which is valid for electrically thick substrates. Predicted values of resonance are compared with previous theories, as well as actual experimental measurements, for radiators approaching one-quarter wavelength in thickness.

Abstract: A simple microstripline feed network for an array module comprising four microstrip elements is described. The advantages and disadvantages of the network are discussed as well as a theoretical explanation for the radiation characteristics of array modules using the network.

Abstract: Superconducting microstrip, with phase velocities of about 0.01c, employing kinetic inductance have been fabricated using niobium nitride and a silicon dielectric. Delay lines using this phenomenon have several advantages for analog signal processing, including low loss and very compact size. Measurements of kinetic inductance microstrip delay lines were made in the frequency domain and the time domain. The results were compared to theoretical predictions and an accurate circuit model was developed. The circuit model was used to determine the frequency- and temperature-dependent losses of the delay line.

Abstract: A method based on spectral-domain analysis is derived to compute effectively and automatically the effective relative permittivity of an open microstrip line. Simple but accurate closed-form expressions are used as the basis functions of the longitudinal and transverse current distributions. The numerical results are shown in tables and figures for various cases and compared WMI other available results. The results presented here are seen as having a high degree of accuracy and may be used as reference standards,

Abstract: New quasi-static models for the computer-aided design (CAD) and analysis of open suspended and inverted microstrip lines are reported. The models are obtained through generalizing those reported earlier and are applicable up to epsilon/sub r/= 20, thereby covering all the practically used substrate materials for these structures. The models also cover a larger range of dimension ratios and are accurate to within 0.6 percent for analysis and within 1 percent for synthesis.

Abstract: Ferrite plating can potentially fabricate a ferrite non-reciprocal component on a microwave monolithick integrated circuit (MMIC); It can make crystalline spinel film in an aqueous solution below 90°C, compatible with the low heat resistance of GaAs devices. To show this, we have electro-plated or electroless-plated Fe 3 O 4 films on GaAs substrates. The film electroless-plated by "spray-spin-coating" method on a SiO 2 intermediate layer (formed by CVD on GaAs) had a mirror plane and a strong adhesion to the surface, though limited in thickness ( \leq 0.8\mu m). A microstrip junction circulator has been composed of a NiZn-ferrite (Fe 2.47 Ni 0.28 Zn 0.25 - O 4 , Ms=478 emu/cc, Hc=37 Oe) film plated on a glass substrate. A circulator action has been observed at 4.0- 4.4 GHz, though very weak (0.6 dB isolation), because the ferrite film (0.8 μm) was much thinner than the substrate (500 μm). The Fe 3 O 4 and NiZn-ferrite films were polycrystalline with a columnar structure perpendicular to the surface. The magnetization did not exhibit anisotropy, lying in the plane of the film.

Abstract: An improved element for use in an electrically steered antenna array is disclosed comprising a dipole, an integral balun and a 180° phase shift bit. The arrangement utilizes printed circuit techniques throughout using an unbalanced microstrip for connection to electrical circuitry, a balun for transitioning from unbalanced microstrip to a balanced dipole antenna and includes a low loss 180° phase shift bit formed by the use of a branched feed network including two diodes whose conductive states determine the sense of antenna excitation, and produce the equivalent of a 180° phase shift bit.

Abstract: A generalized method for evaluating the scattering parameters of a multiport center-fed circular microstrip disk power divider/combiner circuits is presented. The method is based on the planar circuit approach in which the two-dimensional Green's function of a circular segment is used. Various symmetrical power divider/combiner circuits have been designed and tested. The effect of introducing additional shorted ports between the circumferential output ports on the reduction of spurious radiation losses is discussed. Experimental results verifying the design methodology are given.

Abstract: An balun/antenna apparatus is provided which is capable of being fabricated on a printed circuit board substrate by automated equipment. The balun-antenna includes a microstrip groundplane conductor which is split into two balanced ground arms at one end. The split groundplane conductor operates as both a balun and as a radiating conductor. A unique microstrip excitation structure is situated above the split ground elements on the opposed surface of the substrate to excite the antenna with radio frequency energy.

Abstract: A perturbation-iteration solution based on potential theory is developed for determining the effective dielectric constant, characteristic impedance, and current-charge distribution on a microstrip transmission line with isotropic and anisotropic substrates. The numerical implementation of the theory is described and is suitable for use on a personal computer. Computed data for several common substrate materials are included.