Josaphat Tetuko Sri Sumantyo 1 ， Koichi Ito 2, and Masaharu Takahashi 2 1 Center for Environmental Remote Sensing, Chiba University 2 Graduate School of Science and Technology, Chiba University 1-33, Yayoi, Inage, Chiba Japan Phone , Fax * *) ETS-VIII Dual Band Circularly Polarized Equilateral Triangular-Patch Array Antenna for Mobile Satellite Communications Josaphat Tetuko Sri Sumantyo 1 ， Koichi Ito 2, and Masaharu Takahashi 2 1 Center for Environmental Remote Sensing, Chiba University 2 Graduate School of Science and Technology, Chiba University 1-33, Yayoi, Inage, Chiba Japan Phone , Fax

Outline of Engineering Test Satellite – VIII (ETS-VIII) Launch : 2006 by H-IIA Launcher Design Life Satellite Bus : 10 years Mission : 3 years Location : 146 ﾟ E Weight : Approx. 3,000kg (Initial in Orbit) Electric Power : 7,500W Main Characteristics : Large-scale Deployable Reflector, Antenna Feeder, Transponder, Onboard Processor, High Accuracy Clock, Feeder Link Equipment * External view of ETS-VIII* Geostationary satellite

Applications of ETS-VIII

El = 48 o Geostationary satellite Necessity to have the beam formed in the direction of low elevation angle for Mobile Satellite Communications Engineering Test Satellite-VIII (ETS-VIII) Launch in 2006 Orbital experiments on Mobile Satellite Communications Various missions (data communication, mobile satellite broadcasting etc.) Background * ETS-VIII* Direction of the satellite seen from the center of Tokyo

Specifications and Targets of ETS-VIII ETS-VIII * *

Transmission and reception of multimedia information Simple satellite-tracking patch array antenna Small, thin, compact and light (mounted on bullet train, ship and car roof) Low cost Maintenance free ETS-VIII* Simple antenna for ETS-VIII applications Objective *

0.8 cm Previous type of developed patch array antenna (1) Publications: J. Tetuko S.S., K. Ito, D. Delaune, T. Tanaka, T. Onishi, and H. Yoshimura, “Numerical analysis of ground plane size effects on patch array antenna characteristics for mobile satellite communications,” International Journal of Numerical Modelling, Vol. 18, No. 2, pp , March /April 2005 Patents pending : Japan patent No and International patent No. PCT/JP03/05162

Top view Bird’s eye view Side view Previous type of developed patch array antenna (2) Patents pending : Japan patent No , International patent No. PCT/JP03/05162

Previous type of developed patch array antenna (3) Publications: D. Delaune, J. Tetuko S.S., K. Ito, and M. Takahashi, “Circularly polarized rounded-off triangular microstrip line array antenna,” Journal of The Communications Society IEICE (in press) Patents pending : Japan patent No

a b 0.8 mm single feed type dual feed type LHCP b/a=0.98 Easy Stable Circularly polarised triangular patch a b LHCP b/a=1.00

Circularly polarised triangular patch h1 h2 a b /4 patch microstripline (unit : mm) plastic screws Antenna model Fabricated antenna J. Tetuko S.S. and K. Ito, "Circularly polarised equilateral triangular patch antenna for mobile satellite communications," IEE Proc. Microwaves, Antennas & Propagation (in press)

Developed antenna : dual band patch array antenna Reception (Rx) a=b=52.2 mm c=10 mm Transmission (Tx) a=b=49.1 mm c=10 mm Substrates h1=0.8mm h2=0.8mm  r =2.17 tan  = w=2.6 mm Tx1 Tx2 Tx3 Rx1 Rx2Rx3 patch microstripline ground x y a w b /4 (top view) Az x z El c h1 h2 J. Tetuko S.S., K. Ito, and M. Takahashi, "Dual band circularly polarized equilateral triangular patch array antenna for mobile satellite communications," IEEE Transaction on Antennas and Propagation, Vol. 53, No. 11, pp , November 2005

Az z x y off beam direction Az =0° Rx2 Rx3 Rx1 beam direction Az = 120° off Rx2 Rx3 Rx1 beam direction Az = 240° off Rx2 Rx3 Tx1 Rx1 : patch ‘on’ : patch ‘off’ In the case of LHCP ， the main beam will be generated -90 o from patch ‘off’ Tx1 Tx2 Tx3 Tx2 Tx3 Tx2 Tx3 port Switching mechanism too easy !

Fabricated antenna Top view Side view Bird eye’s view J. Tetuko S.S., K. Ito, and M. Takahashi, "Dual band circularly polarized equilateral triangular patch array antenna for mobile satellite communications," IEEE Transaction on Antennas and Propagation, Vol. 53, Issue 11, pp , November 2005

Conical-cut plane measurement Elevation-cut measurement Simulation : Zeland IE3D (Method of Moment) Measurement : Anechoic chamber, Graduate School of Science and Technology, Chiba University Simulation and measurement

reception transmission S-parameter

Frequency characteristics : axial ratio El=48 o Az=240 o Az=300 o reception transmission

3.4 dB 5.4 dBic Simulation Method of Moment Finite substrate Reception : gain – axial ratio (conical-cut plane) 5.4 dBic (5 dBic) 3.4 dB (3.0 dB)

38 o 58 o Reception : gain – axial ratio (elevation-cut)

Simulation Method of Moment Finite substrate Transmission : gain – axial ratio (conical-cut plane) 5.9 dBic 1.7 dB 5.8 dBic (5.0 dBic) 2.8 dB (3.0 dB)

38 o 58 o Transmission : gain – axial ratio (elevation-cut)

Developed antenna Pseudo satellite Experiment Outdoor experiment using pseudo satellite under joint research with National Institute of Information and Communications Technology - NICT (November 2004) Outdoor experiment

38 ○ ， 48 ○,58 ○ Graduate School of Science and Technology experiment car pseudo satellite 30.m 48 ○ y z El x y z x antenna

El=38 o El=48 o El=58 o Relative received power [dBm] (f= GHz) Outdoor experiment : Relative received power (conical-cut plane)

Dual-band triangular-patch array antenna - Both Rx and Tx could be switched very well Problems - Isolation and axial ratio - Spurious radiation from the microstrip-line feed Summary Parameters Reception (Rx)Transmission (Tx) MeasurementSimulationMeasurementSimulation Gain (> 5.0 dBic) Axial ratio (< 3.0 dB) MeasurementSimulation Isolation (< -20 dB)

Main considerations : - Easy and stable to switch & dual band - Good gain and axial ratio Thin & light, small and easy to manufacture (proximity feeding) Improvements in this research Future works Outdoor experiment using ETS-VIII El = 48 o Geostationary satellite ETS-VIII* Direction of the satellite seen from the center of Tokyo *

Applications Disaster monitoring Railway network Airplane network Education contents Logistic delivery Ferry service Entertainment contents help me !

Thank you. * ETS-VIII*

Conical-beam antenna ・ Omnidirectional coverage ・ Easy fabrication ・ Low gain A simple antenna for mobile satellite communications that has a beam-tracking antenna with a high gain is developed Beam-tracking antenna ・ Beam turned in the desired direction ・ Necessity of switching devices ・ High gain Antenna types * ETS-VIII*

Outdoor experiment : map Faculty of Law IMIT Graduate School of Science and Technology Pseudo satellite Faculty of Engineering Radio isotope Center Analysis Center 0m 40m experiment area

Transmission-Tx MODEM (288 kbps) U/CSSPA D/CLNA Spectrum analyzer Local Data Transmission Analyzer GHz BPF GPS 140 MHz GHz 140 MHz 3-element patch array antenna for each reception and transmission DAT Distance pulse Reception-Rx Outdoor experiment : Measurement system

Unit Satellite transmission Measurement values at elevation angle 48° FrequencyGHz Transmission powerdBW Feed lossdB Gain of transmission antennadBi EIRP transmissiondBW Distance between satellite to experiment car km Transmission lossdB (simulation value) Polarization lossdB0.2 Fading margindB2.50 G/T measurement value Elevation angle 48 o dB/K C/N 0 receptiondBHz Outdoor experiment : transmission model

Outdoor experiment : Variation of receive power with distance