RF Characterization of Stripline with thick MnFe2O4 Nanoparticle Films Under DC Magnetic Bias Conditions

A new stripline fabricated using MnFe
₂
O
₄
nanoparticle thick films is demonstrated to have multiband frequency selectivity and high attenuation range. Using the Solution Cast method, thick MnFe
₂
O
₄
nanoparticles films were fabricated on the 45 mm×14 mm Liquid Crystal Polymer (LCP) substrate to have an average film thickness of about 30 μm, which was inserted into the trench area of the stripline. The stripline was measured over the frequency range of 0 - 18 GHz at four different RF input power levels spanning from -22 dBm to -7 dBm with a 5 dB steps. The Ferromagnetic Resonance (FMR) effects are observed when the DC magnetic field bias is applied to the stripline under all four power levels. In particular, the FMR effects appear successively within five frequency bands, namely 4 - 8 GHz, 5 - 10 GHz, 8 - 13 GHz, 12 - 16 GHz and 15 - 18 GHz, as the magnetic field strength increases. The exact FMR frequencies under specific magnetic bias strength can be located by calculating the absolute power absorption rate of the MnFe
₂
O
₄
nanoparticles. In addition, more attenuation is observed under stronger bias and the absolute power absorption increases as the RF input power gets larger. This work presents for the first time the characterization of thick MnFe
₂
O
₄
nanoparticle film in terms of the FMR effect using the 3D printed stripline structure, which can be used to fabricate the Frequency Selective Limiter (FSL) in a wide range of power-sensitive, broadband RF and microwave applications.