Investigations into the feasibility of MIMO techniques within the HF band – 
preliminary results 
 
E.M. Warrington, S.D. Gunashekar, S. Salous, S.M. Feeney, H. Zhang, N. Abbasi, 
L. Bertel and D. Lemur 
	 
The concept of multiple input multiple output (MIMO) has become a productive 
area of research in the field of wireless communications with the aim of 
delivering increased data throughput.  However, to date, MIMO research has 
focussed primarily on short-range communications within the VHF, UHF and SHF 
bands, and very little research has been conducted towards exploiting MIMO 
techniques for long-range communications within the HF band.  
 
In order to realise increased channel capacity by means of a MIMO system, it is 
essential that there is sufficient de-correlation between the signals received 
at each of the antenna elements of the receiver array from each of the elements 
of the transmitter array.  At HF wavelengths, the use of homogeneous 
spaced-antenna arrays may require significant spacing to achieve acceptable 
levels of de-correlation.  For this reason, in addition to conventional spaced 
homogeneous arrays, configurations employing heterogeneous antennas at both the 
transmitter and receiver sites are also being employed in the investigation.  
The results of preliminary measurements over two paths, one a 255 km path from 
Durham to Leicester in the UK and the second from Durham to Rennes, France will 
be presented in this paper.