MICROWAVE PHASE-SHIFT USING FERRITE-FILLED WAVE-GUIDE BELOW CUTOFF

Unlike conventional waveguides, lossless ferrite-filled guides may exh ibit a complex propagation factor below cutoff of the dominant TE mode when a transverse magnetic bias field is applied, In that case, the f ield in a very long waveguide has the character of a traveling wave wh ose amplitude decays exponentially with distance from the driven end, The wavelength and the magnitude of the applied bias field are inverse ly related, and at zero field as the gyromagnetic effects vanish in th e ferrite the wavelength becomes infinite, For a bias field of one pol arity, the traveling wave will be a forward wave, and for the opposite polarity it will be a backward wave, This peculiar behavior allows ph ase shift to be produced in a bandpass filter-like structure in which smalt cross-section below-cutoff ferrite waveguide sections alternate with sections of high dielectric constant material.