Shape and material optimization for bandwidth improvement of printed antennas on high contrast substrates

It is well known that high contrast substrates, although suitable for miniaturization lead to smaller bandwidth. To overcome this limitation, a combined shape and material optimization technique is proposed to develop a miniature patch antenna with pre-specified bandwidth performance. The employed design method is the solid isotropic material with penalization (SIMP) technique formulated as a general non-linear optimization problem. As part of the solution technique an adjoint sensitivity analysis and the sequential linear programming method (SLP) are adapted. A key aspect of the proposed design method is the integration of optimization tools with a fast simulator based on the finite element-boundary integral method. This allowed for inhomogeneous material modeling and design to increase the bandwidth of a fixed size patch antenna on a high contrast substrate having a dielectric constant of ε_r=100.