Together with the millimeter wave propagation experiment, the measurement of one minute rain rates has been continued in Nagoya since December 1974. In this paper, the accumulated time distribution or rain rates has been obtained from the rain rate data observed for 20 years from January 1975 through December 1994. The result shows that the accumulated time distribution of one minute rain rates can be represented approximately by the composite logarithmic normal distribution. Moreover, the study includes the characteristics of annual changes of the accumulated time distribution, the accumulated time distributions between two observation points, the accumuiated time distributions for the period of heavy rain, the worst month and the worst wear as well as for others. we also discussed the rain rates conversion ratio for the simultaneous time ratio of the accumulated time distribution of one minute rain rates and ten minute rain rates.
When the elements or an multi-element antenna, such as the Yagi-Uda antenna, are removed from the structure, the parameters concerning the properties of an antenna; namely, the gain, the radiation pattern, and input impedance are affected by removing these elements. A theoretical analysis of the parameters with half the each element of 8-element VHF-TV receiving antenna removed were calculated by Moment Method and radiation patterns were measured by the measuring system developed by us.
Fablication method of radio absorptive in γ-Fe_2O_3/TiO_2 composite materials for VHF and UHF band are studyed. The system which utilizes γ-Fe_2O_3/TiO_2 materials have been studied and their matching thickness with absorbing bandwidth are discussed. The absorption properties of the radio absorptive of 1.3 cm in thickness and 140 MHz in bandwidth centered at 1300 MHz is demonstrated as an experimental example.
This paper describes a newly developped Digital Auxiliary Link between studio and transmitter station for remotea control & supervision signal transmission. In transmitter station, there are a lot of broadcasting equipment such as TV/FM transmitter and emergency generator etc. and these are remote-controlled from the studio. Taking a protection againsta lightning into consideration, conventional line link is replaced with radio 1ink. Result of it, multiplex transmission witha more 6 control channels is made possible by adopting digital radio link.
Digital modulation methods such as QPSK and QAM have been studied for efficient transmission of digital signal such as MPEG through analog lines. Among such modulations, 64QAM has been getting attention for building CATV system because of its effective transmission capability. In order to implement 64QAM transmission system for consumer tuner, biggest obstacle could be phase noise. In this paper, we assume phase noise spectrum of tuner and studied the influence of these spectra to BER of 64QAM system both theoretically and experiment. In conclusion, we obtain a method to astimate the BER based on the phase noise spectra condition.