Rectangular resonators in inverted microstrip and suspended microstrip

Resonant frequency characteristics of rectangular resonators in a generalized shielded suspended substrate line are analysed using a rigorous spectral domain technique. The computed dominant mode resonant frequency of rectangular resonators in a suspended microstrip with centred dielectric, inverted microstrip and suspended microstrip are presented as a function of various structural parameters. These characteristics are distinct from those obtained for a conventional microstrip rectangular resonator. Experiments are carried out in the frequency range 4-18 GHz to verify the computed resonant frequencies for a suspended microstrip with a centred dielectric using first-order basis functions. The results should find applications in the design of inverted microstrip and suspended microstrip passive microwave and millimetre wave integrated circuits.     

Conformal microstrip antennas and microstrip phased arrays

A new class of antennas using microstrips to form the feed networks and radiators is presented in this communication. These antennas have four distinct advantages: 1) cost, 2) performance, 3) ease of installation, and 4) the low profile conformal design. The application of these antennas is limited to small bandwidths. Phased arrays using these techniques are also discussed.     

Measurement techniques in microstrip

A novel technique has been developed for measurement of dispersion and wavelength in microstrip transmission line laid down on an Al2O3 substrate. The frequency range so far investigated has been 4?12GHz, although the method could be satisfactorily used at far higher frequencies. The measurement accuracy is better than within 1%. Techniques for producing well matched transitions to any thickness substrate have also been established.     

Losses in GaAs microstrip

Newly measured data for the loss of microstrip on 4 mil GaAs from DC to 40 GHz are presented. These data were taken from transmission measurements of lightly coupled, multiple-half-wave-length resonators. A comparison of the loss data with the predicted losses from three popular CAE (computer-aided engineering) tools is provided. The loss models provided by two out of three software vendors agree fairly well with measured data through 40 GHz. Since the measured loss roughly follows a square-law frequency relationship through 20 GHz, it should be possible to adjust the loss below this frequency and above 1 GHz by modifying the resistivity of the conductor in the simulator     

A Lumped-Element Circulator without Crossovers (Short Papers)

It is proposed to construct a simple "crossoverless" Iumped-element circulator, which can be made without sophisticated thin-film processing. The circulator can be described by a "delta connected" equivalent circuit. A simple capacitor arrangement can be used to influence the three eigenvalue phases of the circulator independently, thus permitting this circulator to be maximized systematically. A set of computer-generated eigenvalues gives insight into the behavior of the device under varying operating conditions. Preliminary measurements using a very simple pattern on a 0.650-in-diam ferrite substrate show a 20-dB bandwidth of 10 percent and an insertion loss < 1 dB (0.3 dB/min) at L band.     

Inverted microstrip and suspended microstrip with anisotropic substrates

This letter presents characteristics of the inverted microstrip and the suspended microstrip, with anisotropic substrates. The transverse transmission-line method combined with the mapping method and the variational technique in the space domain are used to analyze the impedance characteristics. The data presented should find application in the design of MIC components at millimeter-wave frequencies.     

Broadband microstrip branch-line coupler Broadband microstrip branch-line coupler

The design and measured performances of a broadband branch-line coupler are presented. The broadband coupler was designed by using a four-section branch line topology with a structure of the defected ground. Such a structure can make the impedance of the microstrip line much larger than that without defected structure, even using a normal PCB process. More than 231 Omega was easily achieved by such a defected structure. The measured performance of the broadband coupler agrees well with the results from simulation     

Magnetically scannable microstrip antenna employing a leakygyromagnetic microstrip line

Rigorous full-wave spectral-domain analyses of a magnetically scannable gyromagnetic microstrip leaky-wave antenna are presented. Varying the DC magnetic bias field by ~6.5%, the maximum radiation angle of the leaky-wave antenna, measured from the horizon, shifts from zero to almost 90°     

Resonance in spherical-circular microstrip structures

The resonance problem of a circular microstrip disk mounted on a spherical surface is studied theoretically. The radiator is replaced by a surface current distribution. The effects of the dielectric substrate as well as the curvature effect are taken into account by the Green's function formulation in the spectral domain. A vector Legendre series is defined. Cavity model current distribution is used as the current basis. Galerkin's procedure is used to solve for the complex resonant frequencies. Numerical results show that the effect of the curved surface on the resonant frequency and quality factor of the microstrip patch may be significant. In general, when the radius of the sphere is decreased, the effective radius of the patch will be reduced and the radiation loss is increased     

Hybrid couplers in bilevel microstrip

Hybrid couplers can be built using a bilevel microstrip structure in which two strips are positioned broadside, one above the other. This simple geometry provides large coupling factors without the need for rigorous manufacturing tolerances. Remarkably, if the dielectric constant of one of the layers can be freely chosen, ideal hybrid coupler performance is achievable. Even when the choice of dielectric constant is constrained, good results can be obtained. A technique for achieving optimal design has been developed, and design curves are shown. Experiments confirm design predictions. The reentrant coupler may be analyzed as an interconnection of two bilevel couplers of the kind described here. This provides a simpler analysis than methods used earlier, and in some cases yields more accurate results     

Circular resonant structures in microstrip

Mode patterns of circular disc resonant sections are analysed. Radiation losses are expected to be small for the dominant mode, which would therefore have the highest Q value.     

Complex modes in boxed microstrip

A method is described for obtaining the propagation coefficients and field patterns of a large number of modes for microstrip with a minimum of computational effort. The method uses a discrete space-domain formulation to calculate a large number of higher-order modes in a way which leads to their fast location and which ensures that node modes are missed. This includes those pairs of modes with complex conjugate propagation constants of the type reported for finline, as well as the normal evanescent modes. In addition, the characteristic impedance of microstrip is efficiently calculated. The results presented are obtained using the generally accepted power-current definition and are in agreement with other published results     

High-efficiency avalanche mode in microstrip

High-efficiency-mode operation of S1 avalanche diodes as pulsed oscillators and amplifiers has been observed in microstrip. Impedance and transmission-loss measurement of the circuit are presented.     

Vertical currents in microstrip antennas

An analysis of the radiation characteristics of a vertical current inside a dielectric-layer over ground is carried out. The general solution for the fields is given for the case of a vertical current which is independent of the vertical (z) coordinate. An "equivalence-principle" for the replacement of the vertical current by an appropriate surface current is presented. Expressions for the complex input power and for the power which goes into the lowest order transverse magnetic (TM)-type surface-wave mode are derived. In addition, graphs for the case of a short vertical dipole inside a dielectric-layer over ground for the radiation pattern, radiation resistance, and surface-wave resistance are presented. The calculations described above can be applied to the analysis of vertical feeds and short circuits in microstrip antennas.     

Shielding effects in microstrip discontinuities

As an application of the theoretical method described in a companion paper L.P. Dunleavy and P.B. Katehi (ibid., vol.36, no.12, p.1758-66, 1988), numerical and measured results for open-end and series gap discontinuities and a coupled line filter are presented. Comparisons are also made to predictions obtained with commercially available CAD packages. The results verify the accuracy of the theoretical method and demonstrate the effects of shielding on discontinuity behavior. The experimental techniques used, which involve the through-short-delay de-embedding approach, are explained     

Self-adjusting microstrip antenna

A microstrip circuit operating in the G band is presented. It allows all emitting printed antenna to self-tune its resonance frequency when it is disturbed, in order to stay resonant and matched at the desired transmit frequency. The principle, design and experimental results of the circuit are presented     

一种微带线馈电的宽带圆极化微带天线的设计

提出一种微带线馈电的宽带圆极化微带天线,它由微带馈线、辐射贴片和FR4介质板组成,在辐射贴片的矩形槽对角添加两个环形结构,实现了微带天线圆极化的要求,通过调整微带馈线的尺寸,有效改善了天线的轴比带宽。该天线单元的轴比带宽达到了43.8%(2.5~3.9 GHz)。     

The microstrip laser

We present a novel semiconductor laser structure, the microstrip laser, where the epitaxial laser layers sit directly above a thick gold layer, instead of on a conventional semiconductor substrate. This design provides advantages for both high frequency and high-power performance compared to conventional ridge waveguide structures. Results indicative of an improved structure are presented, including a factor of 3 reduction in the thermal resistance of the microstrip laser compared to a conventional laser     

Nonplanar microstrip arrays

Pattern synthesis using planar arrays was done extensively in the past, mainly in the context of radar antennas where a cosec² beam is required in the elevation plane. The synthesis leads to a set of coefficients for the array elements which may be difficult to realize and which, if realizable, may lead to a very narrow-band performance. In this paper, a new type of array is proposed. The shaped-beam nonplanar array is an array of microstrip elements, where the phasing is not generated through the feeding network, but by shaping the substrate. Microstrip arrays lend themselves well to a configuration similar to the one proposed, and as it is shown, the final thickness of the array does not exceed a few substrate thicknesses     

Parameters of microstrip

The program computes the capacitance, effective permittivity, characteristic impedance and phase velocity of single strips, and of the normal modes of coupled pairs of strips, in an approximation in which the longitudinal components of the fields and the thickness of the conducting strips are neglected. Within this model, the inhomogeneous dielectric is treated in a rigorous manner.