Ladder line elliptic function filter

Claim 2

A band-pass microwave filter comprising a pair of spaced ground plane plates, a network of spaced digits disposed between the ground planes, the digits being one-half wavelength long at a frequency in the filter''s pass band, each digit being terminated at both its ends in short circuits to the ground planes, each digit being stepped in impedance intermediate its ends, and input and output means coupled to the digital network.

Claim 3

A band-pass, microwave filter comprising, a pair of spaced ground plane plates, and a pair of digital network disposed between the spaced ground plane plates, each network comprising a plurality of spaced parallel digits, the spacing between digits being approximately the same in both networks, all the digits in each network being equal in length, corresponding digits of the two networks being substantially in alignment and having their ends joined to form one-half wavelength long digits, each of the half wavelength long digits being short circuited at both its ends to the ground plane plates, and the impedances of the digits in one network being different from the impedances of the digits in the other network, whereby the half wavelength digits are stepped in impedance at the junctions between the two networks.

Claim 4

A band-pass, microwave filter comprising, a pair of spaced ground plane plates, and a pair of digital network disposed between the spaced ground plane plates, each network comprising a plurality of spaced parallel digits, the spacing between digits being approximately the same in both networks, all the digits in each network being equal in length, corresponding digits of the two networks being substantially in alignment and having their ends joined to form one-half wavelength long digits, each of the half wavelength long digits being short circuited at both its ends to the ground plane plates, and the impedances of the digits in one network being different from the impedances of the digits in the other network, whereby the half wavelength digits are stepped in impedance at the junctions between the two networks.

Claim 5

A microwave filter according to claim 2, further including impedance transformers providing input and output coupling to the digital networks, the impedance transformers being additional digits disposed at each end of one of the parallel networks.