Abstract: A ladder-type electric filter circuit apparatus having a plurality of thinner electric filter units wherein each electric filter unit includes a casing of metal into which piezoelectric resonator elements and terminal plates are inserted, and the metal casing is securely mounted on a printed circuit board by soldering. The piezoelectric resonator elements and terminal plates are insulated from the metal casing by an insulating plate and an elastic insulatiang plate which is also served as a vibration or shock absorber for protecting the contained filter from any external vibration or shock propagated through the printed circuit board.

Abstract: In a mobile radio communication system, a control station supplies a traffic adjusting signal to a particular one of base stations, channels allotted to which are used up to a predetermined number in communication therethrough between the control station and mobile stations in the service area thereof provided that some of the channels allotted to an adjacent base station are idle. The signal narrows the service area of the particular base station as by reducing the base station output power. Alternatively, the signal varies a communicable distance of each mobile station in the service area of the particular base station. For example, the signal makes the particular base station raise the mobile station output power to make some of the mobile stations carry out the communication through the adjacent base station. As a further alternative, the signal varies both the service area and the communicable distance.