Abstract: A radio antenna having linear radiating elements, a loading coil electrically connected to these linear radiating elements and a tuning disc located within the loading coil and rotatable about a diameter of the loading coil whereby said antenna can be easily and accurately tuned to the exact frequency of operation selected. The disc is preferably electrically conductive such that when its plane is perpendicular to the axis of the coil the coil will have a minimum inductance.

Abstract: An upper loaded citizens band antenna is provided which is capable of being mounted on various types of mobile antenna mounts designed for use in conjunction with base loaded antennas. By combining the upper loaded antenna with an interconnection means capable of mating with various base loaded mounts, improved transmission and reception is provided while maintaining the convenience normally associated with the base loaded antennas.

Abstract: An impedance matching transformer and isolation inductance construction for a vertical-end fed radio antenna which enables simple manufacturing tecniques to obtain uniformity of impedance matching from one antenna to the next and which enables the use of a sintered magnetically permeable core of a length longer than three inches. The impedance matching transformer includes a two turn primary and insulating means accurately spacing these two turns. The core is made up of a plurality of relatively cylindrical formed short core elements from sintered magnetically permeable material in end to end relationship. Very thin plastic spacers are interposed between the adjacent ends of the core elements and between the sides of the elements and the housing to prevent chipping.

Abstract: A radio antenna which can be readily tuned to the exact frequency of operation, easily coupled to a coaxial feed-line with minimum standing wave ratio and/or which is normally vertical and can be used where horizontal space is at a premium, such as: indoors or on boats. The antenna has a center loading coil, the inductance of which is adjusted by means of a split coaxial sleeve axially moveable relative to the coil. The input impedance of the antenna is adjusted relative to the impedance of the feed-line by means of a coupling transformer, the transformation ratio of which is controlled by means of a coaxial split metal sleeve axially adjustable relative thereto. A coaxial cable wound into a coil around a ferrite core attenuates the high ratio frequency voltage on the end of the antenna to the feed-line. For indoor use, the antenna is housed in an extensible tubular housing which can be extended to engage the ceiling and floor of a room to hold the antenna in vertical position.