Patent ID: 6850131

Claim:
A bandpass filter comprising: a dielectric block of substantially rectangular prismatic shape having a top surface, a bottom surface, a first portion, a second portion and a third portion, the first portion lying between a first cross-section of the dielectric block and a second cross-section of the dielectric block substantially parallel to the first cross-section and the second and third portions divided by the first portion the first portion being positioned between the second and third portions; a top metal plate formed on substantially the entire top surface of the dielectric block; and bottom metal plate formed on substantially the entire bottom surface of the dielectric block; a metal layer formed on a first and second surface of the dielectric block extending from the top surface to the bottom surface of the entire first portion to electrically couple the top and bottom metal plates to each other at the first portion thereby enabling the first portion of the dielectric block and the metal plates formed thereon to act as an evanescent waveguide; an electrical isolation region positioned on the first and second surfaces of the dielectric block between the top metal plate and bottom metal plate at the entire second portion of the dielectric block such that the metal plates formed thereon to act as a first resonator, and an electrical isolation region positioned on the first and second surfaces of the dielectric block between the top metal plate and bottom metal plate at the entire third portion of the dielectric block such that the metal plates formed thereon to act as a second resonator and the top and bottom metal plates are electrically isolated from each other at the entire second and third portions.