Seminar: Increment in Self Interference Cancelation Bandwidth of In Band Full Duplex Transceiver by Antenna with Stable Impedance

29 September 2020, 11.00 AM - 29 September 2020, 12.00 PM

Dr Soheyl Soodmand


Speaker: Dr Soheyl Soodmand 

Talk Title: Increment in Self Interference Cancelation Bandwidth of In Band Full Duplex Transceiver by Antenna with Stable Impedance 


Electrical Balance Duplexers (EBDs) in In-Band Full Duplex (IBFD) transceivers provides Transmit (TX)-Receive (RX) isolation to implement a form of self-interference (SI) cancellation to facilitates simultaneous transmission and reception from single antenna. EBD works by coupling transmitter, receiver, antenna, and balancing impedance using a hybrid junction where the balancing impedance needs to be equal to the antenna impedance to achieve a high isolation. Variations in antenna impedance with respect to frequency significantly reduces the isolation bandwidth and is dominant factor in limiting the isolation. A method based on Sample Standard Deviation is introduced to quantify impedance instability in the frequency domain. Also, a frequency independent antenna with a core structure of equiangular Archimedean spiral is designed to achieve impedance stability in frequency domain. The antenna impedance at an ultra-wideband (UWB) frequency range of 1.5GHz to 4GHz is more smoothened in some design steps using electromagnetic absorbers, capacitive Impedance tuning and modification techniques whilst this electrically small antenna also has circular polarization, electromagnetic compatibility, and suitable radiation efficiency. In comparison with the literature, using this antenna in the EBD stage along with a simpler balancing impedance is resulted to 95 times wider cancellation bandwidth and 9 dB decrement in mean isolation value. 


Soheyl Soodmand completed his PhD scholarship in 2014 from the Institute for Communication Systems (ICS), home of the 5G Innovation Centre at the University of Surrey, Guildford, U.K., where he carried out smart HF RFID IOT systems. Before PhD, he was with the Mobile Communication Technologies (MCT) Co., Tehran, Iran as RF engineer. In 2014 he joined the Drayson Technologies LTD. and Dryson Wireless LTD., London, UK, as senior wireless engineer and thereafter in 2016, he started to research on electromagnetic sensors for SHM & NDT at the Intelligent Sensing and Communications Group, the Newcastle University, Newcastle, UK. From 2018 he joined as research fellow to the Institute of Biomedical Engineering (IBME) and the Botnar Research Centre both at the University of Oxford, Oxford, UK to design regenerative medicine bioreactor. He also serves an honorary research assistant role at the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS) at the University of Oxford, Oxford, UK. From 2019 he is a senior research associate at the Communication Systems and Networks (CSN) group and a member of the Smart Internet Lab at the University of Bristol, Bristol, UK, where he works on 5G transceiver design. He has several papers published in international journals and conferences, and patents. His research interests are antennas, electromagnetic sensors, IoT hardware, RF energy harvesting, RFID, WPT, bioreactors, SHM & NDT, TRX boards, fractals, RF device design and FSS.


Contact information

Please contact Harriet Parks, Smart Internet Lab Project Coordinator - for more information about this talk.

Dr Soheyl Soodmand

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