Patent ID: 8346325

Claim:
An electrical filter comprising: a tubular outer conductor having an outer surface and a longitudinal passage, the longitudinal passage having a longitudinal center axis and a diameter x; an inner conductor having a diameter y, wherein the inner conductor extends through the longitudinal passage substantially parallel to but not collinear with the longitudinal center axis, such that the inner conductor is separated from the longitudinal center axis by a distance w; and a filler material comprising a metal powder, the filler material being disposed in the longitudinal passage, wherein the filler material has a dielectric constant E; wherein the diameter x of the longitudinal passage, the diameter y of the inner conductor, the spacing w between the inner conductor and the longitudinal center axis, and the dielectric constant E of the filler material provide a characteristic impedance Z of the filter according to: Z = 60 E ⁢ a ⁢ ⁢ cosh ⁡ [ 1 2 ⁢ ( x y + y x - 4 ⁢ w 2 xy ) ] .