The present paper studies estimation of the coefficient θ of a linear dependence relation y=θx between two variables x and y from n pairs (y_i, x_i), i=1, …, n, of noise-contaminated observations. This is an old problem where the maximum likelihood estimator or the least square estimator is known not to be a,symptotically optimal. A simple estimator which improves the above one is explicitly given. This is a typical example of semiparametric statistical estimation. The method of estimating functions is used to solve the problem. Information geometry is used for elucidating the set of all the estimating functions and the asymptotic efficiency of the related estimators. A fibre structure is composed on the manifold of a semiparametric model and a dual couple of parallel transports are introduced on the fibres.

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Current distribution is the fundamental physical quantity in antenna analysis and design. So it is important to obtain current distribution of antennas which corresponds to solving boundary value problem based on Helmholtz wave equation. In this paper, typical examples obtaining current distribution of antennas are described using several analysis methods. As an analytical solution, current distribution of an loop antenna and its arrays are shown, which are formulated into integral equations and solved by Fourier expamsion method.a Method of moments, Finite Difference Time Domain method and Mesured Equation of Invariance are described as the numerical analysis methods, and the examples of analyses are shown. Numerical methods are more flexible to antenna configurarions than the analytical method. Since the flexibility seems to be the most necessary points in designing antennas, and the computer technology has advanced so much, numerical methods play major role in the present antenna analysis and design. Although, the application area of the numerical methods significantly expands, it is pointed that numerical methods have some deficiency in dealing with input and output data and in solving large scale objects which should be overcome hereafter to realize the more efficient antenna design tools.

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