This paper presents an analysis of the dose rate in tissue irradiated by an electromagnetic near field of a circular loop antenna. An analytical model comprised of a circular loop antenna located in the vicinity of the semi-infinite plane of a homogeneous biological medium was formulated. A quasi-static hypothesis was not introduced. The theoretical formulation was rigorously developed based on Maxwell equations which used an electric vector potential, cylindrical coordinates and a Hankel transform. The internal electric field E and the specific absorption rate (SAR) were adopted as indices for the dose in the tissue. This formulation was applied to the dosimetry of a high-frequency therapeutic device (HFTD) and experiment of irradiation to a frog web. The frequency of the applied electro-magnetic fields (EMF) was 9-10MHz. The distance between the antenna and tissue was 2.0-3.2mm. The dose of HFTD were 0.75V/m and 0.35mW/kg, respectively. The dose of experiment of the irradiation to a frog web were 0.42-2.08V/m and 0.11-2.69mW/kg, respectively. The SAR values obtained by this analysis were small enough to conclude that the effects were non-thermal. The calculated SARs of these experiments were compared with estimated SARs in experiments on calcium efflux change due to a weak modulated RF field. All were found to be of the same order of magnitude.

Recently, dielectric material with a large relative dielectric constant (εr100) has received much attention as a substrate suitable for microwave integrated circuits. In this letter, an analysis on transmission-line-characteristics of a new type broadside-coupled strip transmission-line is presented which consists of two center strips placed respectively on the upper- and lower-side surface of a rectangular dielectric substrate with a large relative dielectric constant and two ground electrodes placed respectively on the other surfaces of the rectangular substrate. Analytical expressions for characteristic impedances of this transmission-line are given through a conformal mapping technique. The graphs of characteristic impedances and the coupling factor as a function of various waveguide-parameters are also given to facilitate the design works. Using this new strip-line, microwave miniature multi-stage broadside-coupled filters are easy to realize.

A multiport representation of the step junction of two circular dielectric waveguides of different size is given. Continuous spectral modes of the circular dielectric waveguide are discretized at a terminal plane by means of expressing their mode amplitudes in the form of infinite series of orthonormal Gaussian Laguerre function. Applying the mode matching technique, a multiport representation of the step junction is derived. Numerical examples are given where the results are tested for the conservation of power. Also the numerical results are compared with those from Marcuse's approximate methods.

In this letter, an analysis on transmission-characteristics of a new type broadside-coupled strip transmission-line is presented which consists of two center strips placed respectively on the upper- and lower-side surface of a rectangular dielectric substrate with a large dielectric constant and two ground electrodes placed respectively on the other surfaces of the rectangular substrate. Analytical expressions for characteristics of this transmission-line are given througn a conformal mapping technique and numerical results are given to facilitate the design works. Using this new strip-line, microwave miniature multi-stage broadside-coupled filters are easily realized.

A simple simulation approach based on the modified central difference (MCD) method for analyzing the coupling characteristics of coupled transmission lines (CTL) is presented. Gaussian pulse responses on the sense line are demonstrated by graphical expressions. The frequency characteristics of the coupling factor is efficiently derived from the extracted input and output responses by using the fast Fourier transform (FFT) technique. It is shown that this approach is useful to analyze the coupling characteristics of symmetrical and asymmetric multi-section CTL.