Band-pass filter for hyperfrequencies

Claim 1

Band-pass filter for hyperfrequency electromagnetic waves, comprising, in series from an electrical standpoint, n+2 elements (n being a positive integer) formed by an input line, n linear resonators open at both ends and all sustantially of a given length b/2, and an output line, the resonators being arranged in the order of the first to the n-th between respectively the input line and the output line, wherein a combination of n+1 capacitors are provided to respectively couple the input line to the first end of the first resonator, the second ends of the i-th resonators to the first ends of the (i+1)th resonators (i being an integer from 1 to n-1, inclusive) and the second end of the n-th resonator to the output line, and at least one pair of auxiliary linear resonators of length λs/4 λs being the wavelength to be rejected and less than λb) where b is the wavelength corresponding to the center frequency of the filter pass-band, the auxiliary λb/4 resonators of a pair, each pair having one end connected to one of the n+2 elements and being spaced an electrical distance (2 k+1) apart (k being an integer greater than -1), and wherein the linear resonators are half wave conductive strips open at both ends and situated in parallel and along at least a part of their length which are colinear to create a highly compact filter and permitting the auxiliary resonators to be located anywhere along the electrical path between the two filter leads as long as the distance therebetween is maintained at (2 K+1)λb/4.