Radiation characteristics of small loop antenna above perforated finite image plane

Radiation characteristics of a loop antenna, small compared to the wavelength and placed centrally above a perforated finite image plane, are presented. Holes in the image plane typically occur in a multilayer printed circuit boards (PCBs) when vias pass through the second layer which serves as a reflector. A 3D finite element method (FEM) electromagnetic (EM) simulation of a System-in-Package (SiP) synchronous buck converter shows a significant impact of the holes on the characteristics of the converter. A parametric analysis of the impact of the number and radius of holes on the radiated characteristics and on the inductance of a small loop antenna above perforated image plane is performed by 3D FEM EM simulations. Guidelines for a design of multilayer PCBs for magnetically driven sources, such as DC-DC converters, are deduced.