Abstract: A miniature and high performance antenna applicable to a radio communication apparatus and made up of a straight antenna rod and an antenna coil or coil element. A first whip antenna has a first portion retractable into the casing of the apparatus and a second portion constantly positioned externally of the casing. A second whip antenna has a coil element in the form of a loading coil having a predetermined number of turns. The second whip antenna is coaxially provided on the upper end of the first whip antenna and slidable relative to and in the axial direction of the first whip antenna. The second portion of the first whip antenna is movable between a position where one end of the coil element is disengaged from one end of the second portion and a position where the former is engaged with the latter. The antenna exhibits a desirable electric characteristic when pulled out of the casing of the apparatus and, in addition, promotes the efficient use of the limited space available in the casing.

Abstract: An antenna for a portable radio apparatus has a first antenna construction connected to the casing of the apparatus and a second antenna construction affixed to a base plate or earth plate which is incorporated in the casing. The first antenna construction has a movable joint which allows the first antenna construction to move between a first position where it is regarded as forming a part of the contour of the casing and a second position where it is protruded from the contour and regarded as being located in free space. The second antenna construction corrects the matching state of the first antenna construction such that adequate antenna radiation characteristics are set up in the first position. Optimal antenna characteristics are, therefore, achievable when the first antenna construction is in any one of the first and second positions.

Abstract: A mobile radio communication apparatus with an improved antenna for promoting easy manual operations, insuring desirable acoustic characteristics, and preventing the antenna gain from being lowered by user's head or hand during communication. An antenna is mounted on the upper surface of a casing and made up of a rectangular first conductive plate parallel to and spaced apart from the upper surface by a predetermined distance and having a length L.sub.1, a rectangular second conductive plate extending perpendicularly from the first conductive plate and having a height H.sub.2, and a rectangular third conductive plate extending perpendicularly from the second conductive plate and in parallel to the first conductive plate. A short-circuiting plate extending perpendicularly from one side of the first conductive plate by a height H.sub.1 and has a length M as measured in a direction parallel to the length L.sub.1.

Abstract: A synchronization system for a key telephone system, in which information signals are transmitted in a time-division manner between a key service unit and each key telephone set. The information signal is formed by a control signal, a first signal transmitted from the key service unit to the key telephone set and a second signal from the key telephone set to the key service unit. The control signal is formed by a start signal of one-pulse and a variable synchronizing code, which is placed in a time slot following the start signal and which is formed by a plurality of pulses assuming one of predetermined consecutive values in a predetermined order for each transmission frame period. The control signal is transmitted from the key service unit to each key telephone set for each frame period in synchronism with a first counter provided at the key service unit for developing standard of transmission timings.