RF Characterization of 3-D-Printed Tunable Resonators on a Composite Substrate Infused With Magnetic Nanoparticles

Three-dimensional additive manufacturing methods are being continuously improved with great interest in low cost and small size radio frequency (RF) circuits. Recent developments in magnetically tunable microwave/RF components are attractive for externally controlled circuits without influencing RF characteristics. This letter focuses on additive manufacturing of ferroic nanomaterials along with their implementation in frequency-tuned RF circuits using an applied magnetic field. Extraction of the additively manufactured magneto-dielectric composite was performed at S-band frequencies using least squares curve fitting of measured and simulated S-parameters for annular ring resonator modes. Polylactide (PLA) material used for additive manufacturing was extracted to have epsilon = 1.80 - j 0.031. Meanwhile, magnetic CoFe2O4 with 45-nm average nanoparticles size was extracted to have epsilon = 3.10 - j 0.084 and mu = 1.70 - j 0.145; while Protopasta's magnetic filament had epsilon = 1.80 - j0.031 and mu = 2.19 - j0.569. The 3-D printed magnetic composite is used to design tunable annular ring resonators at 2.4 GHz with up to 38-MHz frequency tuning for an applied 1-kG magnetic field.

Automated summary

This letter discusses the additive manufacturing of ferroic nanomaterials and their application in frequency-tuned RF circuits using an applied magnetic field. By adjusting the applied magnetic field, the RF circuits can achieve high tunability, as demonstrated by the design of tunable annular ring resonators.