The rain attenuation in the 12-GHz band and one-minute-rain rate were measured in Tokyo over a four-year period (2000-2003). The statistical characteristics of this data are presented. The one-minute-rain rates at 0.01% of time percentage of year in Tokyo and Osaka are compared to other past and recent values. The comparison of measured rain attenuation in the 12-GHz band in Tokyo and Osaka with prediction by ITU-R methods is conducted. The root-mean-square prediction error of rain attenuation for the prediction by ITU-R Rec.P.618 is evaluated. Convective rain cell effects can be seen in the scatter diagram of one-minute-rain rate and rain attenuation. However, it is found that the effect is not properly accounted for by the slant path length adjustment factor of P.618-8. A reliable rain attenuation prediction requires some revisions of the slant path length adjustment factor with taking local weather characteristics into account for the P.618-8.

Satellite broadcasting in the 21-GHz band is expected to transmit large-capacity signals such as ultrahigh-definition TV. However, this band suffers from large amounts of rain attenuation. In this regard, we have been studying rain fading mitigation techniques, in which the radiation power is increased locally in the area of heavy rainfall. To design such a satellite broadcasting system, it is necessary to evaluate service availability when using the locally increased beam technique. The rain attenuation data should be derived from the rainfall rate data. We developed a method to transform rainfall rate into rain attenuation in the 21 GHz band. Then, we performed a simulation that applied the method to the analysis of the service availability for an example phased array antenna configuration. The results confirmed the service availability increased with the locally increased beam technique.

The Tokyo Tower is the highest self-supporting steel tower in the world. Since it was built in 1958, the Tower has been a symbol of Tokyo and a well-known, major tourist attraction in Japan. The number of visitors reached 130 million in 1998. The highest number of visitors in one day was 40,000. The original purpose of the Tower was the transmitting of TV signals to the entire Tokyo Metropolitan area. As time passed, FM radio antennas and other equipment for public use were added to the Tower. Recently digital terrestrial antennas were installed on the Tower, a remarkable moment in its history. Digital broadcasting will start in 2003, using these antennas. This paper introduces the Tokyo Tower and its antennas, giving its construction history and its future in the coming digital broadcasting era.

The indexes of the degradation of C/N, ΔT/T and I/N, which can be converted from one to another, are used to evaluate the impact of interference on the satellite link. However, it is not suitable to intuitively understand how these parameters degrade the quality of services. In this paper, we propose to evaluate the impact of interference on the performance of BSS (Broadcasting Satellite Services) in terms of the increase rate of the outage time caused by the rain attenuation. Some calculation results are given for the 12GHz band BSS in Japan.

Two frequency sharing criteria for BSS (Broadcasting-Satellite Service) are enacted in Sect.1 of Annex 1 to Appendix 30 to Radio Regulations. These two criteria are pfd (power flux-density) and EPM (Equivalent Protection Margin) values. In this paper, the two criteria are compared and studied from the view point of applicability to the sharing cases between BSS and BSS. In particular, it is shown that in some cases, the EPM criterion contributes to alleviate the problem of “sensitive satellite network”, i.e., one that has relatively low transmission power and is very weak against interference and blocks the new satellite to enter. Disclaimer The views and positions expressed by the authors are strictly personal and do not constitute, nor can be interpreted as, the position of the International Telecommunication Union on the topics addressed in this paper.

A new type of shaped-beam antenna has been studied as a possible candidate for the antenna for the next generation Japanese broadcasting satellite which succeeds BS-2, launched January 23, 1984. The studied antenna employs an offset paraboloidal reflector with elliptical shape, an elliptical corrugated horn and a rectangular one. The studied antenna covers most part of the Japanese main lands with antenna gain of more than 39 dB, Okinawa more than 35 dB and remote islands more than 28 dB. The sidelobe and cross-polar components radiated outside the service area satisfies the WARC-BS on the basis of power flux density on the earth assuming 200 W output power of the transponder.