Teruaki Orikasa

Superconducting Dipole Magnet for SAMURAI Spectrometer

A superconducting dipole magnet for a large-acceptance spectrometer named SAMURAI has been constructed and installed at the RIKEN RI Beam Factory. The important features of the SAMURAI superconducting dipole magnet are a large pole gap, a wide horizontal opening, and a large momentum bite. The magnet is an H-type dipole, having circular superconducting coils and cylindrical pole pieces with a diameter of 2 m and a pole gap of 880 mm. The coils are orderly wound by the wet winding method developed by Toshiba using a Nb/Ti superconducting wire. The upper and lower coils are installed in two separate cryostats and cooled by the liquid helium bath cooling method. Each cryostat has six cryocoolers: one for a coil vessel at 4 K, four for thermal shields, and one for high- TC superconducting power leads. The size of the iron yoke is 6.7 m wide, 3.5 m deep, 4.64 m tall, and the total weight of the magnet is about 650 tons. The maximum magnetic field is 3.08 T at 563 A (1.922 MA turns/coil), which gives a bending power (field integral) of 7.05 Tm. The maximum stored energy amounts to 27.4 MJ and the inductance varies from 396 H to 150 H as the magnetic field increases. The fringe fields are smaller than 5 mT at 0.5 m from the magnet. The construction of the SAMURAI magnet started in 2008 and was completed in June 2011. The commissioning of the SAMURAI spectrometer was successfully performed using RI beams in March 2012.

Cloud profiling radar for EarthCARE mission

Concept and expected performance of cloud profiling radar (CPR) for EarthCARE are described based on preliminary design study conducted to date. High sensitivity and Doppler capability are two significant new features in this CPR. Particularly, Doppler capability is the first attempt to spaceborne atmospheric radar, which requires great efforts in technical development and feasibility validation. We have developed a new numerical simulation method to assess Doppler velocity accuracy applicable to this application, and results are compared with conventional approximation method. Validity and limitation of the approximation method are indicated from comparison with numerical method. It is shown that requirements to radar sensitivity and Doppler measurements will be satisfied. However, because these requirements to CPR are very tough, further detailed study on both design optimization and assessment technique development are necessary. Under radar operation with very high pulse repetition frequency (PRF) required in this CPR, surface clutter interference caused through antenna sidelobes is an important issue. Analysis on this issue and preliminary requirements to the antenna sidelobes are also discussed.

A Study of Large Reflector Antenna mounted on Communication Satellite for Satellite /Terrestrial Mobile Communication System

We have been researching and developing the STICS (Satellite / Terrestrial Integrated Mobile Communication System). For this system, a large satellite antenna technology is very important and we have been studying the antenna with approximately 30m aperture size. This antenna consists of the deployable reflector and the phased array feed and performs the multi beam formation. Number of array elements and beams are about 100 respectively. But the high accuracy of beam control, as pointing, beam shape and side lobe level, will be required because the beam width is very narrow as about 200km at S band. Digital beam former and digital channelizer (DBF/DC) was developed for this system. DBF/DC has excellent flexibility for beam shaping function. In this paper, we summarize study, discussion and experiment of large reflector antenna for STICS, and describe technical issue of this antenna.

Sidelobe suppression of mesh reflector antenna by non-regular intervals

A suppression technique for the grating lobe level due to periodic surface error is proposed. This technique requires making divisions in the radial direction at non-regular intervals. Calculations show that this suppresses the grating lobe efficiently. The radiation pattern shows that practical rates of division can be obtained. This technique effectively suppresses the sidelobe level without changing any fundamental components. such as the number of divisions and the number of parts.<<ETX>>

Cloud profiling radar (CPR) for EarthCARE and synergy algorithm studies

Design study and algorithm development efforts are overviewed with cloud profiling radar (CPR) for EarthCARE mission. EarthCARE is a candidate for the ESA Earth Explore Core Missions and presently Phase A study is ongoing. EarthCARE is jointly proposed by European and Japanese scientists, and CPR is being studied by CRL and NASDA, Japan. The EarthCARE CPR is characterized by very high sensitivity 94 GHz radar with nadir pointing and Doppler measurement capability. CPR is designed to maximize synergy performance in combination with other onboard active and passive sensors. In this report, after summarizing CPR objectives and expected performance in responding to requirements, study topics concerning Doppler capability and variable PRF techniques are discussed. The EarthCARE synergy algorithm development efforts through airborne campaign experiment are also introduced.

Measurement experiment of LTE terminal transmit power for interference estimation in Satellite/Terrestrial Integrated mobile Communications System

Satellite/Terrestrial Integrated mobile Communications System (STICS) employs the frequency sharing between the satellite and terrestrial components for efficient spectrum utilization. It is required to estimate the interference level between the satellite and terrestrial link to realize the frequency sharing because co-channel interference occurs between the satellite and terrestrial link outside the satellite beam. Measurement campaign of the cellular phone transmit power in 3G network operated in Japan has been carried out to obtain the reference data of estimating the interference level. On the other hand, recently, Long Term Evolution (LTE) is rapidly penetrated into terrestrial mobile network in Japan. Therefore, in future application of LTE to terrestrial component in STICS, we have conducted the measurement experiment of transmit power for LTE terminal to estimate the interference level in STICS satellite receiver. Measurement setup to measure LTE signal is studied and a realtime spectrum analyzer is applied to measure the time-and-frequency-based LTE signal. Measurement has been carried out at six to eight measurement sites per mobile communication carrier with population density of from 60 to 27,000 /km2 in Kansai district in Japan for the operational band of 1920-1980 MHz. The initial analysis of the measured data indicates that the correlation between transmit power and population density is not observed in LTE signal. This trend is different from the fact that the correlation between the measured EIRP of 3G voice transmission in LTE terminal and the population density is observed. From these observations we confirmed the trend of LTE terminal transmit power.

Experimental Study of on-Orbit Correction for Beam Direction Variation of Large Reflector Antenna

We have been researching and developing the STICS (Satellite / Terrestrial Integrated Mobile Communication System). For this system, a large satellite antenna is necessary and we have been studying the antenna with approximately 30m aperture size. The reflectors of these antennas are very complex and radiation pattern of antenna can be affected by surface error and distortion. With these large antennas, thermal distortion error especially can have serious implications, causing orbit beam direction errors, distortion of beam shapes, and increasing sidelobe levels. This paper describes the experimental results with the REV (Rotating element Electric field Vector )method measured at multi earth stations using ETS-VIII (Engineering test Satellite VIII) and the evaluation of reflector information (rotation) for correction of wiught of array elements. REV method is very useful to correct the weight of array feed far away from measurement position as from earth station to satellite.

Characteristics of large deployable mesh reflector antennas for future mobile communications satellites

Characteristics of Large Deployable Mesh Reflector Antennas for Future Mobile Communications Satellites Takashi Ebisui, Akio Iso, Temaki Orikasa, Toshio Sugimoto and Shin-ichi Sato* Space Communications Research Corporation SF,Hayakawa Tonakai Bldg.,2-12-5,Iwamoto-cho, Chiyoda-ku,Tokyo 101,Japan A large deployable antenna is essential for effective mobile communication satellites. This paper describes the key technologies needed for such an antenna, our development plan, and characteristics of various scale models. The electrical scale models of the mesh reflector antenna and the mechanical models of the deployable reflector have been constructed to aid in antenna design. Our ultimate goal is a deployable mesh reflector antenna with 30 m diameter. The measured performance of the scale models corresponds closely to the calculated performance. These results will be extremely useful for designing large deployable mesh reflector antennas for mobile communication satellites. characteristics of various scale models. The electrical scale models of the mesh reflector antenna and the mechanical models of the deployable reflector have been constructed to aid in designing the actual antenna. Our ultimate goal is a deployable mesh reflector antenna with 30 m diameter[2]. One of the electrical models is a 1/15 scale model with 2 m diameter and 12 GHz frequency. The other model is a 1/17.5 scale model with 1.7 m diameter and 14 GHz frequency. The partial deployable mechanical model is composed of the Hexa-Link Truss structure. The other mechanical model is the TETRUS (Tetra Trigonal Prism Truss) structure. Both of these partial deployable models have a diameter of 3 m. The experimental measurements and calculations of these electrical and mechanical models are also described.

X Shape Dipole Notch Antenna for Terminal of Satellite / Terrestrial Integrated Mobile Communication System

Research and development of satellite/terrestrial integrated mobile communication system (STICS) is performed to achieve secured and safe society. In this research, a terminal antenna for STICS which has maximum directivity at the elevation angle of satellite direction, is proposed using X shape dipole notch antenna. Directivity and frequency characteristics are calculated using electromagnetic simulator in both without and with human phantom and confirmed suitable directivity.

Development of ka-band satellite tracking antenna for unmanned aircraft system

Toward increased use of unmanned aircrafts (UA), researches and standardizations of the control communication system for UA using satellites in ITU-R and the like have been discussed recently. The National Institute of Information and Communications Technology (NICT) has been developing an on-board tracking antenna system for UA which realizes a communication link between UA and remote pilot through satellite. The tracking on-board antenna is designed for UA and has several features such as low-profile and broadband. In this paper, we explain the results to date and background of this development.