A frequency-dependent hybrid-mode analysis of single and coupled slots and coplanar strips is presented. The dispersion characteristic and characteristic impedance of the structures are obtained by applying a Fourier transform technique and evaluating the resulting expressions numerically using the method of moments. Numerical results are presented and compared with results published by other investigators. The experimental performance of a slot-line coupler is compared with predicted performance based upon the results presented here for coupled slots. Excellent agreement has been obtained in all cases.

Analysis of Coupled Slots and Coplanar Strips on Dielectric Substrate

When an electric field is applied to a ferroelectric material, the microwave permittivity undergoes a substantial change. This change in permittivity can be utilized in microwave devices to produce frequency-agile functions. This paper is a comprehensive review of the work on ferroelectric materials; this includes models of the ferroelectric permittivity and loss tangent, as well as methods of measurement of these properties. New measurements are presented on thin-film strontium titanate and single-crystal strontium barium titanate substrates. These results are compared with the model. A brief discussion is given of the applications of ferroelectric material in microwave devices.

http://iopscience.iop.org/article/10.1088/0953-2048/11/11/021/pdf

Thin-film ferroelectric microwave devices

Characteristics of coplanar transmission lines on multilayer substrates expressed in analytic formulas have been obtained using conformal mapping. The accuracy of these formulas has been verified experimentally on a variety of coplanar transmission lines using differential electro-optic (DEOS) sampling. For coplanar waveguides, the theory differs from the experiment by less than 3%; for coplanar striplines, the differences are less than 6%.

/pdf/characteristics-of-coplanar-transmission-lines-on-multilayer-5fy4vm0q8c.pdf

Characteristics of coplanar transmission lines on multilayer substrates: modeling and experiments

Con formal mapping techniques are used to obtain closed-form expressions for the coplanar line characteristic impedance and its effective dielectric constant in the general case in terms of all finite line dimensions and substrate thickness. Also. closed-form expressions are presented far the case where there is a ground plane on the other substrate surface. These expressions, that can lift calculated manually, are in very good agreement with published experimental results.

Extension of the application of conformal mapping techniques to coplanar lines with finite dimensions

Quasi-TEM analysis of slow-wave mode propagation on coplanar microstructure MIS transmission lines

Conformal mapping calculations of impedance and effective dielectric constant are presented for coplanar waveguide (CPW) lines with finite-substrate thickness. These calculations and experimental data show a departure from the intinite dielectric approximation as the substrate thickness approaches the guide slot width. The quasi-TEM approximation is retained and calculations of static energy density within the substrate are given. This approximation agrees well with field calculations using a finite-element solution to Laplace's equation.

M.E. Davis

Papers

Finite-Boundary Corrections to the Coplanar Waveguide Analysis (Short Papers)