STRUCTURE PERFECTIONNEE DE CELLULES DE FILTRE ELECTROMECANIQUE ET FILTRES PASSE-BANDE LES INCORPORANT

A.AMELIORATION DE LA PRECISION DE LA BANDE PASSANTE D'UN FILTRE ELECTROMECANIQUE PAR RAPPORT A CELLE DU FILTRE ELECTRIQUE CORRESPONDANT.B.LE COEFFICIENT DE COUPLAGE X DE LA CELLULE UNITAIRE OBEIT A LA RELATION(CF DESSIN DANS BOPI)C.FILTRES ELECTROMECANIQUES NOTAMMENT A LARGE BANDE. Each cell includes two longitudinally vibrating cylindrical resonators and a flexurally vibrating coupler connected between the two resonators. The diameter of the coupler is defined by the expression: dc = +TR wherein: dr is the diameter of the resonators lc is the length of the coupler OMEGA +=f+/fo is the upper relative of the band of frequencies to be transmitted, f+ the uper frequency of said band and fo the tuning frequency of the resonators with lo the length of the coupler corresponding to a quarter wave effect dr+=2 pi nrm OMEGA + where m is the order of the vibration mode of the resonators and nr=lr/ lambda o with lr the length of the resonators and lambda o the wavelength at the tuning frequency of the resonators in longitudinal vibration.