Antenna Design for Ultra-wideband Electromagnetic Tomography

D. W. Armitage1, W. Yin1, M. Z. Abdullah1,2, M. Bilal1 and A. J. Peyton1

1 School of Electrical and Electronic Engineering, The University of Manchester, UK

2 School of Electrical and Electronic Engineering, Universiti Sains Malaysia, Penang, 14300, Malaysia Email: d.armitage@manchester.ac.uk

ABSTRACT

In order to achieve high resolution in ultra wideband (UWB) electromagnetic tomography (EMT) it is desirable to maintain a high degree of control of the pulse shape throughout the overall transmission path. Furthermore, for many applications the pulse is significantly attenuated due to the transmission through lossy and/or dispersive media. There is an advantage in maximizing the efficiency of the transmit and receive antennas if poor signal to noise ratios resulting in long averaging times are to be avoided.

This paper describes a procedure for optimizing the design of an UWB antenna based upon the biconical design. Factors such as size and geometry are considered together with the feeder configuration and resistive loading. The optimisation process utilises the Transmission Line Matrix (TLM) method, whose performance is compared with real-world measurements.

We show that within certain constraints, this design philosophy is indeed a useful aid to the successful design of antennas for this application, provided that the simulation method is able to faithfully model the dispersive effects of typical media. Moreover, there is a trade-off between the desirable temporal response and the efficiency for a given antenna pair.

Keywords Ultra wideband, UWB, electromagnetic tomography, TLM, Biconical Antenna, Dispersive media, Optimisation.