Abstract: A crystal holder is provided which is capable of supporting any one of a plurality of piezoelectric crystals having different preselected diameters. The crystal holder includes two side portions, each portion having a stair step-like structure, the stair steps of one side portion leading upwardly and away from the stair steps of the remaining side portion. Each step of one side portion is respectively horizontally aligned with a corresponding step of the remaining side portion such that each step pair thus formed has a different distance therebetween and is thus capable of accepting for mounting one of a plurality of piezoelectric crystals having preselected diameters corresponding to the distances between the steps of the step pairs.

Abstract: A crystal filter including at least one acoustically coupled crystal with at least three resonators thereon with an impedance block connected between the input and output of each crystal and the input and output phases of each crystal being adjusted so that attenuation zeros symmetric about a center frequency are produced to improve the frequency response of the filter without increasing the number of poles.

Abstract: A pager antenna system having two conductive containers which act as radiators and form a dipole antenna is disclosed. A metallic coil constructed of tubular material is positioned between the conductive containers and has a first end electrically connected to one of the containers. The tubular coil forms part of an antenna impedance matching network and also serves as a conduit for wires which interconnect circuit components located in each of the conductive containers. High frequency isolating chokes are connected in series with the interconnecting wires emerging from a second end of the tubular matching coil and prevent these wires from forming low impedance RF paths between the conductive containers. By making the RF impedance matching coil also serve as a conduit for low frequency interconnecting wires, fewer parts are required, the interconnecting wires are shielded from external influences, and low Q chokes can be used by connecting them across points which have a low RF impedance therebetween.