3D Printed Spherical Cavity Resonator With Fine Tuning Using Nanomagnetic Thin Film

Abstract

A frequency tunable spherical cavity resonator using magnetic nanoparticle thin film and 3D printing technology has been designed, fabricated, and characterized. First, an X-band air-filled spherical cavity is designed and 3D printed to resonate at the fundamental TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sup> mode. To tune the resonant frequency, a 35 μm thick magnetic nanoparticle film deposited on a 2 mil Liquid Crystal Polymer (LCP) host substrate is placed at the center plane of the spherical cavity, where the magnetic fields are the strongest. By mechanically rotating the magnetic film every 15°, the magnetic fields are perturbed accordingly, resulting in a 70 MHz of resonance tuning from 7.958 - 8.028 GHz, and an average and minimum tuning step of 11.7 MHz and 4.4 MHz, respectively. The corresponding unloaded quality factors ranges from 539 to 732. This work demonstrates the concept of a light-weight and high quality factor spherical cavity resonator with fine tuning using 3D printing technology and nanomagnetic thin film.