A Narrowband Quasi-Transversal Filter using a Slow-Wave Structure

Previous slow-wave transmission lines for producing large delays have required multi-layer patterning or increased width. A narrow-band slow-wave structure without these disadvantages is proposed for use with tapped delay line (transversal) narrow-band filters. This line has periodic discontinuities, resulting in a pass-and stop-band structure in which the group delay in the pass-bands is very large. A linear phase transversal stripline filter, in which delay is increased by a factor of five, is demonstrated using a previously-published design procedure (which deals with multiple reflections, dispersion and losses) to calculate the filter tap weights. A wide range of both phase and amplitude characteristics should eventually be possible, and superconducting delay lines should ultimately permit losses of only 1 or 2 dB.