Integrated E-Plane Filters with Finite Frequency Transmission Zeros

A new class of E-plane integrated circuit bandpass filter is introduced which provide high skirt selectivity and may have asymmetric transfer function. Extracted pole resonators are used to give finite frequency transmission zeros which can be placed asymmetrically on the s-plane imaginary axis. The extracted pole resonators are realised by parallel coupled finline tracks. The resultant structure consists entirely of a single circuit board or metal insert as with a conventional E-plane filter. Practical results are presented for an initial design of an asymmetric 11.6GHz finline filter.