A Wide-Band, High Isolation UHF Lumped-Element Ferrite Circulator

A novel, spiral trace topology for a lumped-element, ferrite circulator is demonstrated in this letter. By employing this new topology, along with various optimization methods, we achieve high isolation and wide bandwidth for UHF applications. Based on simulation data, circulator isolation of 30 dB or more is possible over the 245-355 MHz frequency range. The isolation response of a fabricated spiral trace circulator exceeds 30 dB, but over a shifted and wider frequency range of 260 to 390 MHz.