Sometime electronic devices are disturbed by unknown R.F. noises. To solve this problem, it is need to restudy the present technology for R.F. noises as following subjects ; continuous oscillation and damped oscillation. disturbance for receivers and electronic devices. CISPR measuring method for damped oscillation, and mechanism of R.F. noises induced in distributed constant circuit, merit and demerit of XY condenser, once disturbance for electronic device during one years and ete.

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most of R.F noises which are the source of disturbance for electronic devices their power supply lines. Mains of them are damped oscillation which induced at opening and closing the circuit. Let discuss the noise generation mechanisms and their suppression thchniques when closed the load.

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Radiation noise from the electronic equipment is controlled by the standards such as FCC, VDE, VCCI and so on, and noise reduction is very important for the manufacturers. Printed wiring board (PWB) is the noise source of the radiation. So studying the generation mechanism of the radiation and reducing it on the PWB level is most effective for the noise reduction. We have aimed the estimation of the radiation from the PWB by calculating the radiations from each patterns on the PWB and integrated them. In this report, the calculation techniques of the radiation from single pattern on the PWB is shown. The radiation depends on the common mode current, in this experiments, and is calculated from the common mode current by using simple equation. The calculated results are compared to the experiments and good qualitative agreements are obtained.

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Recently, signal grounds and protective grounds are going to be integrated with a view to reducing the voltage difference caused by lightning surge. But there is a little bit hesitation about the integration because of conductive noise from AC power mains. In this paper, the difference between the separated grounding system and integrated grounding system are studied, and the following results are obtained. (a) Separated grounding system will be better for reducing the noise currents from AC power mains to telecom. equipment. (b) On the other hand, integrated grounding system will be better for reducing the noise current from telecom. equipment as rectifier to the other equipment.

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This paper presents a formulation of ferrite absorber by the Spatial Network Method. In the formulation. the movement of domain wall and the rotation magnetization of ferrite correspond to hysteresis and relaxation charactristics, respectively. Results show that this formulation is appropriate for ferrite absorber and suggest that hysterisis loss of the movement of domain wall widen band width of ferrite absorber.

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A method for calculating site-attenuation for vertical polarization by equivalent conversion to four-teminal networks is presented. Its theoretical values, four-terminal constants, image-impedance and propagation constants are calculated. And also hight pattern of site-attenuation, frequency characteristics of site-attenuation are shown. Change of power transmission ratio according to the load impedance is also analyzed to investigate the mismatch of impedances between feeder and receiver.

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Two kinds of double-layer absorbers according to the design method Proposed in a previous paper, have been tested. They consist of BaTiO_3 ceramics for the 1st layer and Paints of ferromagnetic materials for the 2nd layer. Absorption properties have been measured in a microwave anechoic Chamber by the use of the phase-interference method. The results obtained are summarized as follows : (1) paint absorber for 8.5GHz band,combined with BaTiO_3 Ceramics and Ni-zn ferrite. Ratio of its thick(ness to the central-wave*length is 1/50. The frequency band of reflection loss at 10dB is 650NHz. The weight is 3.3Kg/m^2. (2) paint absorber for 10GHz band,combined BaTiO_3 ceramics and Hn-Zn ferrite Ratio of its thickness to the central wave-length is 1/25. The frequency band of reflection loss at 10dB is very wide to be 2550MHz. The weight is 4.8Kg/m^2. Thus, by choosing appropriately a combination of the electrical constants of the layer materials wider-ranged frequency characteristics can be obtained comparared to the conventional single-layer absorbers.

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We have developed 32kbps radio data transmission systems which use frequency band of 1.2GHz and small power radio equipment with anntena power under 100mW. This paper describes contribution and consideration of 32kbps radio data transmission systems.

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