Substrate Integrated Artificial Dielectric (SIAD) Structure for Miniaturized Microstrip Circuits

A substrate integrated artificial dielectric (SIAD) structure for planar microstrip circuits miniaturization is presented. This structure is paraelectric and paramagnetic, i.e., provides enhancement of both the permittivity and the permeability from a given host substrate, and therefore achieves guided wavelength compression, leading to circuit size miniaturization. The SIAD is fully integrated and may be engineered by repeatable laser drilling and metal plating processes. By proper design of the SIAD, the effective parameters of a given host substrate are estimated to be increasable by up to 100% for the permittivity and up to 40% for the permeability, corresponding to a guided wavelength compression factor of up to 67%. Two practical applications are demonstrated for the proof-of-concept, a stepped-impedance low-pass filter and a branch-line coupler. For the proof-of-concept design used (nonoptimal in terms of size reduction), the former exhibits a length reduction of 16% and the latter exhibits an area reduction of 33%. The proposed SIAD structure may find many variations for manipulating the size, flexibility, and dispersion properties of microwave circuits, and may also be used for quasi-optical planar lenses.