Mathematical modeling of waveguide transitions

Results of simulation of waveguide transitions performed at the Department of Mathematics of the Faculty of Physics, Moscow State University, are presented. Synthesis of waveguide transitions is based on the incomplete Galerkin method and the finite-difference technique formulated in the direct and projection forms (the finite-element method) and involves the Tikhonov regularization method.     

VLF propagation across discontinuous daytime-to nighttime transitions in anisotropic terrestrial waveguide

Discontinuity effects are analyzed after referring the ionospheric surface impedance of daytime and nighttime waveguide portions to the same common altitudeh. The properties of the waveguide junction are determined by field matching, and the resulting linear equations are rearranged in a form that permits a sequential determination of transmission and reflection coefficients. Simple dominant mode approximations of the transmission and reflection coefficients are also developed. Field calculations of reciprocal geometries illustrate the consistency of the formulation and reflection coefficients are found to be of negligible magnitudes. The discontinuous surface impedance tends to excite higher order waveguide modes of larger amplitudes than a ground based source in homogeneous waveguide.     

Ultra-wideband balun and power divider using coplanar waveguide to microstrip transitions

An ultra-wideband transition from coplanar waveguide (CPW) to a pair of microstrip lines is presented in this letter. It is shown that the proposed transition can be used to devise an ultra-wideband T-junction power divider with equally split in-phase output signals. More importantly, it is demonstrated that the out-of-phase magnetic currents in the slots of the CPW can be utilized to achieve an out-of-phase power divider or a balun. Both the T-junction power divider and the balun benefit from compact size and good performance over an ultra wide frequency band from 3 to 16 GHz. Prototypes of both proposed devices are fabricated and measured to provide an experimental verification on the concept and numerically predicted features.     

Comparison of mode-matching and differential equation techniques inthe analysis of waveguide transitions

The solution of the continuous waveguide transition problem can be obtained by discretizing the boundary and applying mode matching or by using a system of ordinary differential equations. Both approaches involve approximate representations of the boundary. When using the differential equation approach, it is found necessary to consider the transition as several sections in series in order to avoid numerical instabilities. When this is done, one may cascade using a generalized scattering matrix approach or a generalized ABCD matrix method. Results are shown in order to compare the accuracies of the boundary discretization approach and the differential equation approach for the Marie transducer and for linear transitions of various lengths in rectangular waveguides. Experimental results are also given for the Marie transducer     

Wideband coplanar waveguide RF probe pad to microstrip transitions without via holes

A novel via-less coplanar waveguide (CPW) to microstrip transition is discussed and design rules based on simulations and experimental results are presented. This transition demonstrates a maximum insertion loss of 1 dB over the frequency range from 10 GHz to 40 GHz with a value of 0.4 dB at 20 GHz. This transition could find a variety of applications due to its compatibility with RF systems-on-a chip, low loss performance, low cost and its ease of fabrication.     

一种V波段波导-微带对极鳍线过渡结构的设计研究

文章研制了一款V频段的波导微带转换器,该转换器采用对极鳍线过渡结构,并提出了一种抑制谐振及基片安装引起的高次模的设计方案。实际测试回波损耗小于-21 dB,插入损耗小于1.6 dB。     

Spectral-domain analysis of E-plane waveguide tomicrostrip transitions

The spectral-domain technique and a residue calculus theorem are used to compute the input impedance of a microstrip transition to a rectangular waveguide. The transition consists of a printed circuit board inserted into a waveguide housing along the E-plane. The effects of the dielectric layer are considered in the present analysis. The behavior of the input impedance of the transition is studied with respect to the critical dimensions of the probe length and backshort location. Calculated results by the new formulation agree well with those computed using an integral equation and those measured at Ka -band frequencies     

The continuous spectrum of the inset dielectric guide and itsapplication to waveguide transitions

The analysis of discontinuities in open waveguides, particularly strongly radiating discontinuities, requires a knowledge of the complete modal spectrum of the guide. The continuous spectrum of nonseparable open waveguides, a category which includes many useful high-frequency structures, may be developed from a characteristic Green's function approach. The continuous hybrid spectrum of the inset dielectric guide (IDG), a structure that shows promise for both propagation and antenna applications, is presented as an example. As a verification, this spectrum is used in the analysis of strongly radiating rectangular waveguide to IDG transitions, and a good correlation with experimental data is achieved     

Microstrip antennas

Microstrip antennas have been one of the most innovative topics in antenna theory and design in recent years, and are increasingly finding application in a wide range of modern microwave systems. This paper begins with a brief overview of the basic characteristics of microstrip antennas, and then concentrates on the most significant developments in microstrip antenna technology that have been made in the last several years. Emphasis is on new antenna configurations for improved electrical performance and manufacturability and on advances in the analytical modeling of microstrip antennas and arrays     

Microstrip antennas

Microstrip antennas consist of a planar resonant radiating element parallel to, but separated, from a ground plane by a thin dielectric substrate (t ll lambda). These antennas are very thin and consequently rugged and easy to mount. They may be fed from the back through the ground plane or from the edge by depositing microstrip lines on the dielectric substrate. Several varieties of microstrip antennas are discussed in this paper. Design procedures are given for both linearly and circularly polarized antennas. Measured patterns are presented for antennas from UHF throughCband.     

一种微带魔T

文中详细介绍了一种微带一微槽双重接头的作用机理,并在微带一微槽过渡接头和魔T的设计中得到证实,表明它可在微波集成电路中有广泛的应用.     

Microstrip antenna technology

A survey of microstrip antenna elements is presented, with emphasis on theoretical and practical design techniques. Available substrate materials are reviewed along with the relation between dielectric constant tolerance and resonant frequency of microstrip patches. Several theoretical analysis techniques are summarized, including transmission-line and modal-expansion (cavity) techniques as well as numerical methods such as the method of moments and finite-element techniques. Practical procedures are given for both standard rectangular and circular patches, as well as variations on those designs including circularly polarized microstrip patches. The quality, bandwidth, and efficiency factors of typical patch designs are discussed. Microstrip dipole and conformal antennas are summarized. Finally, critical needs for further research and development for this antenna are identified.     

Microstrip Characteristic Impedance

A recent paper by Bianco et al. gives five definitions of microstrip characteristic impedance which do not have the same frequency dependence. This paper shows that the most widely used definition can be based on wave-impedance and is a unique unambiguous characteristic impedance for microstrip, consistent with characteristic impedance definitions of other waveguiding structures.     

Microstrip Dispersion Model

The assumption that the quasi-TEM mode on microstrip is primarily a single longitudinal-section electric (LSE) mode leads to a transmission line model whose dispersion behavior can be analyzed and related to that of microstrip. Appropriate approximations yield simple, closed-form expressions that allow slide-rule prediction of microstrip dispersion.     

Microstrip array technology

Past and present technological developments in microstrip antenna arrays are summarized. Emphasis is on exploring the potential of such arrays for satisfying the requirements of advanced military and commercial applications.     

Losses in Microstrip

Expressions are derived for the conductor loss in microstrip transmission lines. The formulas take into account the finite thickness of the strip conductor and apply to the mixed dielectric system. Good agreement with experimental data is obtained for rutile and alumina substrates.     

Microstrip loss calculations

Loss calculations have been performed for microstrip lines by relating the longitudinal component of current to the charge distributions obtained without the substrate. Comparison with experiment shows good agreement.     

Microstrip U-shaped resonators

Influence analysis of U-shaped microstrip resonators?? parameters and parameters of dielectric substrate on resonant frequencies and unloaded quality-factor of resonators is conducted. Three kinds of U-shaped resonators are considered which differ in operation modes at the resonator??s ends: short-circuit or no-load. It is revealed that in cases of small spacing between the arms of U-shaped resonators distribution of their resonant frequencies significantly differs from the corresponding quarter-wavelength or half-wavelength resonators and leads to decreased stop-band in pass-band filters based on them. Experimental research shows that decreasing the spacing between the arms of U-shaped resonators leads to decrease in quality-factor by 20?C30%. Experimental samples were manufactured on substrates with ? _r = 92 and ? _r = 38.     

Microstrip circular-segment antenna

The analysis of the electromagnetic properties of the circular-segment microstrip antenna with microstrip feed is presented. The theory employs an equivalent magnetic wall model, treating the antenna as a lossy flat cavity. A series expansion in resonant modes yields an approximation of input impedance, radiation characteristics and near field data of the antenna.