Introduction

High performance frequency selective surfaces (FSSs) have a myriad of applications in the advanced sensor, radar, and communication systems. The most common FSS is a twodimensional (2D) periodic array of thin conducting or aperture elements etched on a flat or curved dielectric surface. This structure usually exhibits a frequency filtering characteristics similar to the frequency filters in traditional radio-frequency (RF) circuits. In this seminar, we’ll review and discuss various multi-band FSS used in the multi-band communication systems. Specifically, we’ll first discuss the resonant frequency stability feature of the FSS with single or double fractal elements. Then its applications in multi-band Satellite or Wireless Communication systems will be described. Finally, the FSS with split-ring-resonator (SRR) elements will be introduced and applied to the multi-function phased array antenna systems.

 

About Speaker

Dr. Te-Kao Wu received B.S.E.E. from National Taiwan University in 1970, M.S. and Ph.D. degree in Electrical Engineering from University of Mississippi in 1973 and 1976, respectively. He has 46 years professional experience as the Research & Development (R&D) Engineer of Electromagnetics, FSS, and Antennas, in Northrop Grumman, JPL, and Hughes Aircraft companies. Back then he worked on various government or internal research and development (IR&D) sponsored satellite communication, user terminal, and radar antenna systems. He is currently consulting in the field of FSS and metamaterials for applications in radome and wireless communication. He has published more than 200 technical papers, 27 U.S. patents, 1 book, and 2 book chapters. He was awarded fourteen NASA Certificates of Recognition for technical innovation research works in antennas.

time and place:2017/8/28 [Mon] 3:00 pm Rohm Building, Room 10-206

Introduction

The talk revolves around an advanced radiating electromagnetic surface, while emphasizing on its application to an emerging class of Ka-band satellites. A dual-circular-polarization reflectarray is demonstrated which generates two independent beams, depending on the polarization of the incident field. To form the structure, a low-profile polarizer, which converts circularly polarized (CP) waves into linearly polarized (LP) waves, is cascaded with a typical dual-linear-polarization (DLP) reflectarray. This way, the two impinging CP waves are converted to two orthogonal LP waves so that the DLP reflectarray only interacts with LP waves. This conversion simplifies the process of applying independent reflection phases to orthogonal waves, which is required for the control of the beams. Once the phase-shifted LP waves are reflected, the polarizer converts them back into the original CP waves. This systematic arrangement enables the structure to receive two right-hand and left-hand CP waves and direct them in two arbitrary directions. The proposed reflectarray could also be viewed as a new class of metasurfaces, which can simultaneously manipulate the polarization state of the incident waves and the phase-profile on the aperture. In addition to the operational principles of the reflectarray, the talk includes an overview of the multiple-beam antenna concept for multi-gigabit satellite links. In this context, the capability of the proposed reflectarray as a low-cost solution to some of the fundamental challenges is highlighted.

 

About Speaker

Dr. Mehdi Hosseini received his BSc and MSc degrees, both in Elec. Eng., from the K.N. Toosi University of Technology and Tarbiat Modares University in 1999 and 2003, respectively. After graduation, he joined the Iran Telecom Research Center, working on modern antenna design for satellite and terrestrial communications. In 2007, he joined the Space Research Institute, Tehran, where he was engaged in the system engineering of satellite communications systems. In Jan 2011, Dr. Hosseini began his PhD studies with the University of Saskatchewan (UofS), Canada. Upon completion of his degree in Sep 2014, he was appointed as a Postdoctoral Fellow with the UofS, with activities including the design and microfabrication of periodic antennas at the Synchrotron Laboratory for Micro and Nano Devices of the Canadian Light Source. Following this, from March to Sep. 2015, he was involved in the conceptual design of a dualband phased array antenna for backhaul radios, within Canada's premier R&D internship, Mitacs. This project was tackled as a joint activity between the UofS and the DragonWave Inc., Ottawa, Canada. Finally, in Jan 2016, he joined the University of Toronto as a postdoctoral fellow, where he currently works on advanced reflectarray antennas. Dr. Hosseini is the recipient of several awards, such as the Outstanding MSc Student Award, the UofS Graduate Scholarship, and the Saskatchewan Innovation and Opportunity Scholarship. He is also a frequent winner (2013/2014) of the IEEE Outstanding Presentation Award. Dr. Hosseini has authored over 36 papers and serves as reviewer for the IEEE Antennas & Wireless Propag. Letters, IEEE Trans. on Microwave Theory Tech., IEEE Trans. on Antennas Propag., IEEE Antennas & Propag. Magazine, IET Microwave, Antennas & Propag. and some other IET journals.

time and place:2017/8/23 [Wed] 10:00 –11:00 am Rohm Building, Room 10-206

Introduction

The talk revolves around an advanced radiating electromagnetic surface, while emphasizing on its application to an emerging class of Ka-band satellites. A dual-circular-polarization reflectarray is demonstrated which generates two independent beams, depending on the polarization of the incident field. To form the structure, a low-profile polarizer, which converts circularly polarized (CP) waves into linearly polarized (LP) waves, is cascaded with a typical dual-linear-polarization (DLP) reflectarray. This way, the two impinging CP waves are converted to two orthogonal LP waves so that the DLP reflectarray only interacts with LP waves. This conversion simplifies the process of applying independent reflection phases to orthogonal waves, which is required for the control of the beams. Once the phase-shifted LP waves are reflected, the polarizer converts them back into the original CP waves. This systematic arrangement enables the structure to receive two right-hand and left-hand CP waves and direct them in two arbitrary directions. The proposed reflectarray could also be viewed as a new class of metasurfaces, which can simultaneously manipulate the polarization state of the incident waves and the phase-profile on the aperture. In addition to the operational principles of the reflectarray, the talk includes an overview of the multiple-beam antenna concept for multi-gigabit satellite links. In this context, the capability of the proposed reflectarray as a low-cost solution to some of the fundamental challenges is highlighted.

 

About Speaker

Dr. Mehdi Hosseini received his BSc and MSc degrees, both in Elec. Eng., from the K.N. Toosi University of Technology and Tarbiat Modares University in 1999 and 2003, respectively. After graduation, he joined the Iran Telecom Research Center, working on modern antenna design for satellite and terrestrial communications. In 2007, he joined the Space Research Institute, Tehran, where he was engaged in the system engineering of satellite communications systems. In Jan 2011, Dr. Hosseini began his PhD studies with the University of Saskatchewan (UofS), Canada. Upon completion of his degree in Sep 2014, he was appointed as a Postdoctoral Fellow with the UofS, with activities including the design and microfabrication of periodic antennas at the Synchrotron Laboratory for Micro and Nano Devices of the Canadian Light Source. Following this, from March to Sep. 2015, he was involved in the conceptual design of a dualband phased array antenna for backhaul radios, within Canada's premier R&D internship, Mitacs. This project was tackled as a joint activity between the UofS and the DragonWave Inc., Ottawa, Canada. Finally, in Jan 2016, he joined the University of Toronto as a postdoctoral fellow, where he currently works on advanced reflectarray antennas. Dr. Hosseini is the recipient of several awards, such as the Outstanding MSc Student Award, the UofS Graduate Scholarship, and the Saskatchewan Innovation and Opportunity Scholarship. He is also a frequent winner (2013/2014) of the IEEE Outstanding Presentation Award. Dr. Hosseini has authored over 36 papers and serves as reviewer for the IEEE Antennas & Wireless Propag. Letters, IEEE Trans. on Microwave Theory Tech., IEEE Trans. on Antennas Propag., IEEE Antennas & Propag. Magazine, IET Microwave, Antennas & Propag. and some other IET journals.

time and place:2017/6/1 [Thu] 2:30 –4:00 pm Rohm Building, Room 5-203