LSE/sub 20/-Mode Characteristics in Phase-Shifter Parametrization

The validity of considering the LSE/sub 20/-mode propagation threshold as the limiting factor in selecting rectangular-wave-guide ferrite-phase-shifter dimensions is examined theoretically and experimentally using a dielectric model. Depending on the effective dielectric constant of the loading material, it is shown that the LSE/sub 20/-mode cutoff may, in many cases, be exceeded without introducing spurious mode resonances. In addition, the effect of magnetization on the y-independent modal cutoffs is investigated. It is concluded that the dielectric model represents a worst case condition as far as higher order mode propagation is concerned.