Three-Dimensional Near-Field Pattern Shaping Antenna Array with Arbitrary Focus Configuration

In this paper, a 24-element microstrip antenna array with three-dimensional near-field pattern shaping capability for microwave hyperthermia is presented. The antenna array operating at 2.45 GHz is designed based on the weighted constrained method of the maximum power transmission efficiency (WCMMPTE). By setting proper constraints for the electric field distribution of several selected points within the target area, the three-dimensional (3D) shape of the electric field can be characterized, meanwhile ensuring that the power is maximally concentrated in this area. Moreover, the shape, size, and spatial location of the three-dimensional area are all adjustable according to the selection of those specific points, making the array quickly adaptable for different actual requirements. The electric field distribution of the preset 3D shape can be focused at center or off-center with optimized excitations fed into the array. The measured electric field distribution shows that the transmitting array antenna is able to achieve a preset 3D shape of the electric field distribution as well as a preset offset position in the desired direction, agreeing very well with the simulations.