Biography: Prof. Dau-Chyrh Chang, IEEE Life Fellow, obtained his BS degree and MS degree from Chung-Cheng Institute of Technology, and Ph.D. degree in Electrical Engineering from University of Southern California. He spent 25 years in antenna R&D at CSIST. For 17 of these years, he served as director of antenna section. During his employment at CSIST, he developed reflector antennas, phased array antennas, slot array antennas, communication antennas, and various antenna test ranges. In 1998, he left his post as director of the antenna section to become Dean of the Engineering School at DYU (Da-Yeh University). He had been invited to be the Dean of College of Electrical and Communication Engineering at Asia Eastern University of Science and Technology (former as Oriental Institute of Technology) in 2006. He has been the Chair Professor and Director of Communication Research Center at AEUST from 2006 to 2016. He has been established four laboratories during executing various research programs, lab of hybrid antenna near field antenna test range, lab of TRP/TIS communication measurement system, lab of EMC, and lab of EM simulation. Except for various kinds of antenna research, Prof. Chang is also focus on the research on SI (Signal Integrity) with the funding support from industries. Since August 2016, he changes his career from academy to industry as consultants for several companies. He has published over 400 papers at journals and conferences and have 35 patents.
Prof. Chang established the IEEE AP-S Taipei Chapter and as the first Chair in 2001, Chair of IEEE MTT-S Taipei Chapter and President of Chinese Microwave Association in 2000-2002. He has been the General Chair of conferences or workshops, such as CSTRWC2001, CSTRWC2008, ISAP2008, ICONIC2009, AEM2C2010, IEEE iWEM2011, CSQRWC2012, PIERS2013, IEEE MTT-S IMWS-Bio 2015. He received many research awards when he was at CSIST, DYU, and AEUST. Prof. Chang received IEEE Life Achievement Award in 2022.

Title: Efficient measurement of ground user terminals and ground stations in LEO satellites

Abstract:
Large constellations of low earth orbit (LEO) satellites provide Internet access any place in the earth. They could help bridge the digital divide, particularly in rural regions, mountains, and oceans. In general, the user terminals or ground stations in earth use phased array antenna or reflector antennas to track the fast-moving LEO satellites during data communication. In order to verify the user terminals or ground stations work properly for precise beam tracking of fast-moving satellite, handover from satellite to satellite, wave fading during propagation, data throughput, etc., a simulator to simulate the LEO satellites for ground user terminals or ground stations is required.
Ground user terminals or ground stations receive or transmit plane waves from or to LEO satellites during data communication. Traditional plane wave can be generated by CATR (compact antenna test range). The surface mechanical error of reflector, the spillover field from feed sources, and the diffraction field from edge of reflector are dominated the QZ (quiet zone) performance in test zone area. In general, the edge diffraction field can be minimized with edge treatment by rolled edge or serrated edge. the feed spillover field to the QZ could be reduced by covering absorbers. Multiple movable plane waves can be generated by multiple CATRs to simulate LEO satellites inside anechoic chamber. The mutual coupling among CATRs and feeds spillover to the QZ will cause the degradation of QZ for multiple CATRs. This talk will describe a brand-new TCATR (toroidal CATR) with multiple movable plane wave toward the cylindrical QZ. TCATR composes of a toroidal reflector inside main anechoic chamber and multiple movable feed systems inside another small anechoic chamber. Since there are not any edge discontinuity for toroidal reflector, the edge diffraction field is disappeared inside QZ. The feed spillover field to the QZ will be absorbed inside the small anechoic chamber. The QZ size of TCATR is a cylindrical shape with diameter is one quarter diameter of torus and height is two third height of torus. It does not only simulate fast-moving LEO satellites to verify the ground user terminals or ground stations but also save time for antenna power pattern measurement. The theory and characteristics of TCATR and traditional CATR will be compared during the talk.