A novel design of a compact multilayer resonator using double-sided microstrip

A novel design of a compact multilayer resonator is proposed using a double-sided microstrip. This resonator consists of two quasi-lumped elements: a square spiral inductor and a microstrip patch capacitor. Each quasi-lumped element is printed on different layers the upper and the lower dielectric layer separated by a common ground plane. The maximum dimension of this resonator is less than lambda(g) /25, where lambda(g) is the guided wavelength of a 50 Omega microstrip line at the resonant frequency. The design methodology is exemplified by a second-order multilayer bandpass filter that is based on the proposed resonator. The filter is fabricated and measured, and the simulated and measured results are in agreement.