Abstract: A multiband antenna comprises an antenna device which is resonant at two or more different frequencies. The antenna device comprises a first antenna rod (7), a second antenna rod (8), and a distributed-constant dielectric resonator which is a coaxial dielectric resonator (1A) comprising a dielectric block (1A1). The first antenna rod (7) is electrically connected to an inner conductor (4) covering the inner surface of the dielectric block (1A1). The second antenna rod (8) is electrically connected to an outer conductor (5) covering an outer periphery of the dielectric block (1A1). In another structure, the dielectric resonator is a triplate dielectric resonator (1B) comprising two dielectric plates (1B1). The first antenna rod (7) is electrically connected to a center conductor (6) interposed between the dielectric plates (1B1). The second antenna rod (8) is electrically connected to outer conductors (5) covering the dielectric plates (1B1) at the side opposite to the center conductor (6).

Abstract: A multi-functional chip-type piezoelectric filter of a simple configuration comprises a multilayer structure which includes a plurality of piezoelectric substrates provided with oscillating sections having respective frequency response characteristics that are different from each other, a plurality of conductive terminals formed on the outer surface of the multilayer structure and connected to the respective oscillating sections of the piezoelectric substrates so that the oscillating sections may be selectively used.

Abstract: A dual-band nonreversible circuit device comprises a first circulator element (91) and a second circulator element (92) accommodated in a single housing (50, 50', 60) and operable around a first center frequency (f.sub.A) and a second center frequency (f.sub.B), respectively. The first circulator element (91) is formed by a combination of a first permanent magnet (31), a first ferrite plate (21) with a first center conductor (11), and a ground conductor plate (40) successively stacked on a lower magnetic yoke (50). Likewise, the second circulator element (92) is formed by a combination of the ground conductor plate (40), a second ferrite plate (22) with a second center conductor (12), and a second permanent magnet (32) successively stacked and covered by an upper magnetic yoke (60).

Abstract: In a battery charger for use in charging a secondary battery, a display unit displays a necessary charging time which is left until completion of charging operation. The battery charger adopts a constant-voltage and constant current control method. A memory memorizes charging voltage and charging current characteristics of the secondary battery. A voltage detecting circuit detects a charging voltage of the secondary battery and produces a detected voltage signal. A current detecting circuit detects a charging current of the secondary battery and produces a detected current signal. A control circuit decides the necessary charging time on the basis of the charging voltage and charging current characteristics, the detected voltage signal, and the detected current signal. The necessary charging time is displayed on the display unit in the form of numerals and the like.

Abstract: A battery pack of the present invention and uses a lithium ion secondary battery and is capable of adjusting the output voltage when temperature around the battery pack is low and causes the voltage of the secondary battery to drop. Therefore, the battery pack outputs a constant voltage on its output terminal without regard to the ambient atmospheric temperature.

Abstract: A miniature and high performance antenna applicable to a radio communication apparatus and made up of a straight antenna rod and a loading coil. The tip of the straight antenna rod is received in the coil such that capacity coupling is set up between them. An antenna configuration is provided for setting up capacity coupling between the antenna rod and a feed portion.

Abstract: An antenna mounted on and retractable into a casing of a portable radio communication apparatus. When the antenna is pulled out of the casing, it plays the role of a .lambda./2 whip antenna. Even when the antenna is retracted into the casing, it has substantially the same gain as when pulled out from the casing.

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.