Radio Research Laboratories Research Articles

Initial Results of the Ichon Solar Radio Spectrograph

A new solar radio spectrograph to observe solar radio bursts has been installed at the Ichon branch of the Radio Research Laboratory, Ministry of Information and Communication, Korea. The spectrograph consists of three different antennas to sweep a wide band of frequencies in the range of 30 MHz ∼ 2500 MHz. Its daily operation is fully automated and typical examples of solar radio bursts have been successfully observed. In this paper we describe briefly its hardware and data processing methods. Then we present coronal shock speeds estimated for 34 type II bursts from May 1998 to November 2000 and compare them with those from other observatories. We also present the close relationship between onset time of type II bursts and X-ray flares as well as their associations with coronal mass ejections.

Toshiyuki Yonezawa (1915–2001)

Toshiyuki Yonezawa, an AGU member for 30 years, died in Tokyo, Japan, on 6 April 2001 at the age of 86. He became an AGU member in 1960 (Planetary Sciences).Born on 14 February 1915 in Tokyo, he graduated from the physics department of the Faculty of Science, University of Tokyo, in 1942 and entered the Radio Physics Laboratory of the Ministry of Education in Tokyo (Kokubunji). This establishment was later reorganized to become the Radio Research Laboratory, Ministry of Posts and Telecommunications, and it was here that he followed his distinguished career in ionospheric physics until his retirement in 1974.

Global distribution of nitric oxide produced by lightning and its seasonal variation

The global distribution of NO production due to lightning has been estimated using the lightning discharge frequency observed from the global distribution of thunderstorm activity obtained from the ISSS‐b satellite observations during June 1978 to May 1980 and issued by Radio Research Laboratories, Japan. The seasonal and latitudinal variation has been investigated. The annual production of NO by lightning from the present study is found to be 2 Tg N yr−1.

Reflections on the influence of Wrld War II on e lectrical engineering education in the United States, 1925- 1955

There is little doubt that World War II reshaped electrical engineering education in the United States. Having watched physicists outperform electrical engineers in wartime radar laboratories, prominent educators overhauled the EE curriculum by introducing more mathematics, science, and electronics after the war. A leader of this movement was Frederick E. Terman, head of the Harvard Radio Research Laboratory (RRL) during the war and later Dean of the School of Engineering at Stanford University. Terman believed that the increased government and military sponsorship of research after the war raised the "intellectual level of electrical engineering on the campus." Recent studies have supported Terman's assessment that the large infusion of research funds through such post-war agencies as the ONR, NSF, and the Joint Services Electronics Program played a key role in creating the present EE research and graduate education programs in the United States [l].

VLBI Activities in Japan and a Projected Space-VLBI Program

There are three institutes in Japan that are equipped with VLBI facilities. Of these, Nobeyama Radio Observatory started VLBI experiments with astrophysical and astrometric interests. The Institute of Space and Astronautical Science, the Nobeyama Radio Observatory, and the Radio Research Laboratory collaborated with JPL and other institutions for this first space-VLBI test experiment, generating fringes on ground-TDRSS satellite baselines at S band. A working group formed by scientists of the above three Japanese institutes proposed to ISAS to launch a space-VLBI satellite. The project, called VSOP, for VLBI Space Observatory Program, is described here.

Research activities on time and frequency transfer using space links

Time and Frequency (T/F) transfer systems using space links developed at the Radio Research Laboratories (RRL) are described. The domestic T/F transfer system uses the Japanese communication satellite: CS-2/broadcasting satellite BS-2 and the Global Positioning System (GPS) in addition to the ordinary links of ground TV and Loran-C The Asian area transfer system makes use of the Geostationary Meteorological Satellite (GMS) and a Very Long Baseline Interferometer (VLBI) as well as Loran-C Other systems for international T/F transfers depend on the space techniques of the GPS and the, VLBI. Spread-spectrum equipments for T/F transfers have recently been built to realize both precision and accuracy of about 1 ns via the CS link, together with a 1-m mobile antenna station. Receivers have been developed at RRL to be used routinely for the GPS and GMS T/F transfers on a daily basis with a precision of 10 ns or more and an accuracy of less than 100 ns. T/F transfer experiments using a VLBI system developed at RRL have been conducted on a routine basis about once a month with the U.S. Naval Observatory since April of 1985. The present goal of accuracy is 10 ns with 10-min or longer observations.

Radio Research Laboratories, Ministry of Posts and Telecommunications

Radio Research Laboratories, Ministry of Posts and Telecommunications

Centimeter wave propagation experiments using the beacon signals of CS and BSE satellites

The wave propagation experiments using Japanese geostationary satellites CS (20/30 GHz) and BSE (12/14 GHz) satellites have been performed at the Kashima earth station of the Radio Research Laboratories (RRL). Cumulative rain attenuation and cross-polarization discrimination (XPD) statistics are given for the period of three years at 11.7 GHz (vertical polarization) and for the period of four years at 19.5 GHz (circular polarization). It is shown that the yearly rainfall rate and attenuation distributions are well approximated by log-normal distributions, and the XPD distribution is well approximated by a normal distribution. Monthly and time-of-day variation of the attenuation and XPD distributions are presented. Duration statistics of attenuation and XPD are presented and characterized. Other characteristics in the wave propagation, such as effective path length, frequency dependence of attenuation, and joint statistics of attenuation and XPD are derived and discussed. Rainfall events are classified into three rainfall types, stratus, cumulus, and others using measurements of the radar reflectivity factor along the satellite-to-earth path, and the dependence of XPD characteristics on the rainfall type is also presented and discussed. Some prediction methods of calculating attenuation and XPD statistics are applied to the data obtained in these experiments and the predicted results are compared with the measured ones. It is found that some corrections are needed when the XPD statistics are predicted from the attenuation statistics using the theoretical relation between XPD and attenuation.

John Hasbrouck Van Vleck, 13 March 1899 - 27 October 1980

. Van Vleck’s long career at Harvard University, where he became professor in 1934, and in 1951 succeeded Bridgm an as Hollis Professor of Mathematics and Natural Philosophy, lasted to his retirement in 1969. He was Chairman of the Department of Physics from 1945 to 1949, and Dean of Engineering and Applied Physics from 1951 to 1957. During World War II he was head (1943-45) of the theory group at the Radio Research Laboratory at Harvard University, which was concerned w ith radio counter-measures. Throughout these periods, and afterwards in retirement, the steady flow of important scientific papers never ceased. His career was crowned in 1977 by the award of the Nobel Prize for Physics, jointly with his former student P. W. Anderson and Sir Nevill Mott.

Recent Activities on Time and Frequency at the Radio Research Laboratories

The recent activities on time and frequency at the Radio Research Laboratories (RRL), Tokyo are briefly summarized in the following outline:(i) Atomic time scale: Two algorithms for calculating a highly uniform time scale have been developed in order to establish TA(RRL), and the results of the comparison between TA(RRL) and the time scales of foreign organizations are given. (ii) Dissemination of standard frequency and lime signal: A brief description on the measuring and controlling system of the standard frequency and time signal transmissions, JJY (MF and HF) and JG2AS (40 kHz) is given. (iii) T and F satellite experiments: International time-transfer experiment via Navigation Technology Satellite (NTS-1) showed the accuracy of several hundred nanoseconds. Besides, simple correction for ionospheric time delay ruduced the standard deviation by 30% compared with that of the raw data. Experiments of the dissemination of frequency and time were made in 1979 and also in 1980 using the experimental broadcas...

CESIUM BEAM FREQUENCY STANDARD AT THE RADIO RESEARCH LABORATORIES

A laboratory type cesium beam frequency standard has been developing at the Radio Research Laboratories, Tokyo. Design consideration, some of the analysis and basic experiments have been made. The construction and performance of the beam tube and the electronics are mainly reported.

Propagation characteristics of millimetre and centimetre waves of ETS-II classified by rainfall types

A propagation experiment at the frequencies of 1.7, 11.5 and 34.5 GHz using Engineering Test Satellite Type IIEts-II was conducted at the Kashima earth station of the Radio Research Laboratories (Rrl).Several meteorological parameters were also measured simultaneously at the station using rain gauge networks, a C-band rain radar, a 35 GHz radiometer and meteorological instruments.

Propagation characteristics for millimeter and quasi-millimeter waves by using three Japanese geostationary satellites

Propagation experiments using the following geostationary satellites, Engineering Test Satellite-II (ETS-II), Medium-Capacity Communication Satellite for Experimental Purposes (CS), Medium-Scale Broadcasting Satellite for Experimental Purposes (BSE) and Experimental Communication Satellite (ECS), are being conducted by Radio Research Laboratories (RRL) with the co-operation of National Space Development Agency of Japan (NASDA), Nippon Telegraph and Telephone Public Corporations (NNT) and Japan Broadcasting Corporations (NHK). The Experimental Communication Satellite (ECS) will be launched into the geostationary orbit in February 1980. This satellite will then be used for further propagation experiments. The various and numerous propagation data obtained by using these satellites is being collected from many places all over Japan. The summary of the propagation experiments conducted at the main station is as follows. 1. (a) Experimental periods covered in this paper are about 1 year for ETS-II and CS, and six months for BSE. 2. (b) The percentages of time in which measured attenuation exceed 5, 10 and 15 dB are 0.7, 0.3 and 0.15% respectively at 34.5 GHz (ETS-II), 0.08, 0.016 and 0.008% respectively at 19.45 GHz (CS), 0.025, 0.0025 and 0.0009% respectively at 11.7125 GHz (BSE), and 0.02, 0.0023 and 0.001% respectively at 11.5 GHz (ETS-II). 3. (c) Duration of attenuation exceeding 30 dB at 34.5 GHz is less than 50 min with the occurrence probability of 0.013% for a one year period. Attenuation exceeding 6 dB at 11.5 GHz and the one exceeding 10 dB at 19.45 GHz are 0.0025% (8 min in a year) and 0.015% (10 min in three months). 4. (d) In the cumulative distributions of XPD (Cross Polarization Discrimination), values of XPD exceeding the percentages of time, 0.3, 0.1, 0.03 and 0.01% are 25, 22, 19 and 17 dB respectively at 34.5 GHz, 28, 23, 20 and 16.5 dB respectively at 19.45 GHz and 33, 29, 26 and 24 dB respectively at 11.5 GHz. This paper presents an outline of the propagation experiments carried out by using ETS-II, CS, BS and ECS, and propagation characteristics of radio waves mainly above 10 GHz at the main station (Kashima Branch, RRL).

ETS-II Experiments Part II: Earth Station Facilities

A part of the Earth station at the Kashima Branch of the Radio Research Laboratories has a highly sensitive receiving system newly designed for receiving 3 coherent and weak beacon signals transmitted from the Engineering Test Satellite Type-II (ETS-II) of Japan and obtaining propagation data on quasimillimeter and millimeter wavelengths. The ground system includes a main receiving station which has a 10-m diameter antenna for multifrequencies, highly sensitive receivers, a rain radar, which has many unique functions, a radiometer, meteorological instruments, and data processing computers. The facilities of the main receiving station for ETS-II propagation experiments, except for the rain radar, are described.

Propagation experiment with Japanese satellite, ETS-II (KIKU-2)

The first Japanese geostationary satellite, Engineering Test Satellite Type II [Kiku-2], has been successfully placed at 130°E at the beginning of March 1977. Using beacon transmitters at three coherent frequencies of 1.7, 11.5 and 34.5 GHz which are installed in ETS-II, the Radio Research Laboratories (RRL) of the Ministry of Posts and Telecommunications (MOPT) conduct propagation experiments to obtain preliminary information for the Experimental Communication Satellite (ECS) experiment. The experimental system for propagation experiment with ETS-II is composed of a main receiving station, a rain radar, a radio-meter, meteorological instruments and data handling computers. The receiving data, including signal levels of co- and cross-polarization in these frequencies and phase differences between each of these frequencies and polarization, are sampled every 200 msec. The satellite-to-Earth propagation experiment at the highest frequency has been satisfactorily started on 11 March 1977.

The dive and ascent satellite program for lower ionosphere research

Lower ionosphere is a transition region from outer-space to low atmosphere and had been unexplored on a continuous basis before Atmosphere Explorer satellites flew in the region. Purpose of a new aeronomy satellite, DAS (Dive and Ascent Satellite) having a capability to control orbits and flying at the very low perigee altitude less than 130 km is to explore the bottomside of ionosphere spreading over between 100 and 300 km altitudes. Preliminary study on the new aeronomy satellite is conducted at National Aerospace Laboratory in cooperation with Radio Research Laboratories and Meteorological Research Institute. This paper reviews the mission design, orbit decay and transfer analysis, typical orbit profile, aerodynamic characteristics and satellite configuration study, aerodynamic heating and thermal control analysis, attitude control analysis, on-board propulsion and power subsystems, and operation analysis with emphasis on their technical feasibility.

Technical Aspects of The Japanese Broadcasting Satellite Experiments

After a successful launch of the Japanese Medium-Scale Broadcasting Satellite for Experimental Purpose (BSE) Yuri in April 1978, check-outs of the satellite and the transponder were conducted by the National Space development Agency of Japan (NASDA) for three months. In July, Radio Research Laboratories (RRL) of the Ministry of Posts and Telecommunications (MOPT) and Nippon Hoso Kyokai (NHK: Japan Broadcasting Corporation) initiated various kinds of satellite broadcasting experiments which will be continued for three years. This paper presents brief description of the BSE program and the preliminary results of the experiments.

Design of and Preliminary Results on a Cesium-Beam Standard at the Radio Research Laboratories

A laboratory type cesium beam standard is being constructed for experimental use as a working standard at the RRL of Japan. Ihe structural design and experimental results on the phase adjustment of Ramsey cavity, the beam optics employing hexapole magnets, and an axial C-field, and the digital servo system are described. Methods for evaluating the beam velocity distribution employing a pulse technique and the analysis of the Ramsey pattern are examined. Observed intensity of Ramsey signal proved satisfactory, and other experiments are now proceeding.

Large outbursts in Cygnus X-3

Two radio outbursts in Cyg X–3 were observed during December 1973 and January 1974. The source was observed at 4.2 GHz using the 26-m radio telescope of Kashima Branch of the Radio Research Laboratories, which has a half power beamwidth of 10 arc min. Flux densities were obtained using drift scan so as to avoid interference from HII regions surrounding Cyg X-3. An average of four or five scans was taken to determine the flux densities. The receiver gain was calibrated during each determination using the output from a noise tube. It was also calibrated at five hour intervals by observing 3C147 (assumed flux density 9.3 Jy—1 Jansky=1 f.u.—) and 3C274 (80 Jy) in December 1973, and 3C123 (19.0 Jy) in January 1974. We measured the total flux densities alternately in orthogonal planes of polarisation by rotating the polariser, except on December 23 and 24, 1973. On those occasions the flux densities were measured in only one plane of polarisation. The pointing accuracy was checked frequently by the scans with declination offset. The error in flux density is less than 0.3+0.05S4.2 Jy, where S4.2 is the flux density at 4.2 GHz.

Spectrum control procedures for the national radio astronomy observatory

The Green Bank site for the National Radio Astronomy Observatory (NRAO) and the Sugar Grove site for the Naval Radio Research Laboratory (NRRL) were located fairly close together with the hope that both could share in the locally relatively low radio noise environment that existed when the installations were first built. The procederes which have been followed to maintain, as far as possible, the scientific value of this environment are described, and some examples of the degree to which this effort is succeeding are given. Similar problems will arise at the site chosen for the very large array (VLA) in New Mexico and these are discussed briefly.