The aim of this study is to establish a method for estimating rain attenuation distribution and site diversity effect for earth to satellite links using frequencies above 10 GHz. In the case of lognormal distribution of rain rate distribution, theoretical formulas for the rain attenuation distribution, as well as for the site diversity effect on slant propagation paths, have been derived in terms of rain rate distribution, rain rate spatial correlation function, raindrop layer height, and rain attenuation coefficient. Theoretical rain attenuation distribution function values have been compared with empirical values, which are based on 3 years observation by a sun-tracking radiometer at Musashino (Tokyo). Good coincidence has been recognized between them in the interval where the cumulative distribution function value is greater than 0.01%. Regarding site diversity effect, comparison of theoretical values has been made, not only with the empirical values in Japan, but also with those recorded in pertinent British and American publications. The coincidence has been good in the interval where the single rain attenuation distribution value is greater than 0.01%. The estimation method, described in this article, has sufficient accuracy for practical use.

It is well known that networks containing both lumped and distributed elements can be treated by the theory of mpr's (multi-variable positive real functions). In the theories of cascade synthesis so far developed for those mixed networks, it has been emphasized that the value of network functions depend only on one variable at any transmission zero. So that, the component sections were composed of J-element (Jun-element) p_i and its I-element (Inverse-element) p_i¹. However, a certain class of multi-variable transfer functions does generally have transmission zeros depending on a set of several variables. In the present paper, the separation of the sections which produce transmission zeros depending on two variables, are discussed. In the result, the separation of the four reactance sections are discussed. These four sections correspond to A (or B), Richards, Brune and Hazony-Youla sections for one-variable case.

Buried-heterostructure lasers (BH lasers), having a narrow active region and a low threshold current, oscillate stably in a single transverse mode in a wide range of driving currents above threshold. In addition, no significant kinks can be observed in the light output vs. current characteristics. Sinusoidal modulation characteristics of BH lasers are measured especially with respect to frequency response, spectrum broadening and nonlinear distortion. From experiments, it is exhibited that BH lasers have a flat frequency response up to 2 GHz, with less spectrum broadening than conventional wide stripe lasers, and a low 2nd-order distortion of about 50 dB below the fundamental level. This distortion is favourable when compared to LED's. These results demonstrate the feasibility of BH lasers as promising optical sources with linear and wideband modulation capabilities.

Algebraic properties of the set of regular states for a given hierarchically structured learning objectives are discussed. The set is proved to be a distributive lattice, if two operations, meet and join, are properly defined on it. The derived algebraic properties of the set are then applied to some of the procedures in the learning diagnosis and treatment (LDT) reported earlier.

This article describes about the PNPN diode-transistor switching circuit with automatic turn-off mechanism, and the pulse voltage level discriminator fabricated as its application.