Microstrip Frequency Doublers Based on a Thin Magnetic Film

Abstract

The article presents the results of measuring the generation of the second harmonic in a microstrip transmission line and in a quarter-wavelength stepped-impedance microstrip resonator with a thin permalloy magnetic film (Ni <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">80</inf> Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</inf> ). The measurements were carried out for three samples with different thicknesses – 50 nm, 75 nm and 100 nm, at an input signal excitation frequency of 1 GHz and maximum input power of ~3500 mW. It was shown that the level of the second harmonic rises as the TMF thickness increases. It was found that a 100-nm sample generates the second harmonic more efficiently due to the larger ΔH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FMR</inf> and the larger amount of magnetic material involved in the process of nonlinear conversion of the input power. It was shown that the resonator-based frequency doubler has a conversion factor ~4500 times higher than that of the doubler based on the microstrip line due to the higher value of the loaded Q-factor. Therefore, a quarter-wavelength stepped-impedance microstrip resonator can be used as a frequency doubler.