Optimal Design Of Array Antennas For Therapeutic Applications Of Electromagnetic Fields

In medicine, non ionizing electromagnetic fields are exploited both in therapy, to induce some kind of biological effect in a region of interest, and in diagnostics, to obtain information of clinical interest from signals generated in response to an external electromagnetic excitation. Here we deal with the therapeutic applications of microwaves, in particular with the design of the phased arrays exploited to generate the required fields. The main aim is to enlighten the conceptual points lying behind the optimal design of such apparatuses, putting in evidence the peculiar challenges to be faced, which entail the need of a reformulation of the classical array synthesis problem and put absolute limits on the achievable performances. After presenting such reformulation, we review some recent results providing a procedure for addressing the optimal design of the system layout, i.e., the choice of the number and locations of the array elements. Then, with reference to the case of microwave hyperthermia, we report some examples to show how the procedure can be carried out in practice, putting in evidence the limits of the achievable performances and the problems still open.