Field Desoription for Multi-Slot Fin-Line Struotures

A generalized fin-line structure is analyzed, which shows several slots in the metal coating of the substrate. Possible applications of such a structure are e.g. directional couplers and 3 dB hybrids. Out-off frequencies, phase constants, and electric and magnetic field patterns are calculated by a numerical approximation method. Results are presented for the specialized cases of isolated and earthed finlines both with one and two slots of varying width. As an application, the calculated and measured performance of a bandstop filter is given.