An experimental investigation into the feasibility of MIMO techniques within the HF band Abstract MIMO research so far has primarily focussed on the VHF-SHF frequency bands with an aim to increase the data rates achieved over a limited spectrum. MIMO requires a rich scattering environment in order to create parallel spatial data pipes between antennas at the transmitter and the receiver. The HF band is also affected by the multipath effects through reflections in the different layers of the ionosphere and hence is a suitable candidate for MIMO. It was determined that antenna modelling could be used to design small, collocated antenna arrays for HF-MIMO application.This research may act as the foundation stone on which the future endeavours into the application of MIMO techniques in the HF band could be built.iii Acknowledgement It is a pleasure for me to thank the people who contributed towards this research. My gratitude goes to Professor Mike Warrington who supervised this research and was always willing to encourage and support me in addition to the invaluable input and suggestions. Dr. David Siddle as co-supervisor was always there to listen and advise, no matter how busy he was. I would also like to acknowledge Dr. Salil Gunashekar for his forthcoming support and co-operation throughout this project.I am indebted to my wife who supported me all along and showed great patience. She shielded me from many day to day worries and allowed me the time and space to concentrate on my research.