Microwave Characterization and Performance Assessment of Polymer-Magnetic Nanocomposites using Transmission-Line Based Microwave Resonators

This paper presents the synthesis and microwave characterization of superparamagnetic polymer nanocomposites with uniformly dispersed 8nm Fe3O4 nanoparticles for RF and microwave applications. Microstrip linear resonators (MLR) with modified substrate structures have been designed at microwave frequencies (2.5GHz) and employed to characterize the changes in the intrinsic properties of the polymer nanocomposites. In addition, frequency characteristics of the resonator have been examined under ambient conditions (i.e., 24°C and 1Atm of pressure) while applying external magnetic fields up to 0.6 Tesla. Frequency tunability of 37 MHz (1.5%) and unprecedented improvement in the loaded quality factor QLoaded from 13 to 70 (5.4X increase) have been observed, with 13.7dB of reduction in the insertion loss from 24.2dB to 10.5dB.