Effects of Realistic Magnetic Field in Ferrite on the Waveguide Circulator for Industrial Applications

Abstract

Industrial rectangular waveguide circulators (WR340), with narrow bandwidths of 50 MHz, are available in markets for a hefty price tag depending upon the frequency range. This paper focuses on designing a partial height ferrite circulator with a homogeneous applied bias field to achieve a wider operating bandwidth of 210 MHz. With the frequency centered at 2.45GHz, insertion loss less than 0.24 dB, reflection, and isolation better than 20 dB can be achieved. The circulator studies usually consider a homogeneous applied bias field to the ferrite in simulation, but this is not the case in actual products where permanent magnets are used to produce the magnetic field to ferrites. Hence, we implement a self-consistent model that provides a non-homogeneous applied bias field to the ferrite to show the importance of considering a realistic magnetic field in the simulation of ferrite waveguide circulators. The design and development are performed using the finite element method (FEM) simulations. In the self-consistent model that applies a non-homogeneous bias field, a bandwidth of from 100 MHz to 170 MHz can be achieved with some geometric modifications from the former design, highlighting the importance of considering a realistic magnetic field.