Tailoring Fe80Co20 Composite Material for High Permeability at High RF Frequency for Antenna Applications

Snoek’s law is a well-known theory describing the relationship between the ferromagnetic resonant frequency, f res , and the static permeability, $\mu_{s}$, in magnetic materials. Within the limits imposed by Snoek’s law, higher $\mu_{s}$ leads to lower f res and vice versa. Recently, Rogers Corporation introduced MAGTREXTM 555 magneto-dielectric material. It has permeability and permittivity of 6 and 6.5, respectively, along with low magnetic and dielectric loss below 500 MHz, which is also governed by Snoek’s law. Thus, extending f res to higher frequencies while keeping the value of $\mu_{s}$ relatively high, is imperative for developing higher GHz-range magnetic devices for antenna substrates and other applications. This can be achieved by controlling the dimensions and orientation of magnetic, fine, thin flakes or nano-particles of $FeS_{80}Co_{20}$ in polymers. In this paper, we focus on fabricating low-loss $FeS_{80}Co_{20}$ composite materials using two different techniques: electrodeposition plating and sputtering processes. The prototype is then measured using waveguide system to confirm its magnetic properties.