Generation of a focused electromagnetic field inside a tissue medium by using short baseband pulses

The possibility to achieve focusing in a three-layer cylindrical biological tissue model, by using concentrically placed TEM waveguide applicators excited by short baseband pulses, is examined rigorously. The medium response to time harmonic excitation of the TEM array is predicted, by solving the associated boundary value problem. Then, the medium response to pulsed excitation of the array is considered and a Fourier series representation is used in order to obtain the time dependence of the electromagnetic fields produced at any point within tissue. Numerical results are computed and presented and the use of time coincidence is examined, in order to achieve focusing at a specific point of interest within tissue.