Abstract: A communication antenna comprises an electrically conductive base assembly at a lower section of the antenna; a loading coil assembly, at a midsection of the antenna, and electrically connected to the base assembly; and a re-entrant capacitive hat assembly, at an upper section of the antenna, and electrically connected to the loading coil assembly, wherein the re-entrant capacitive hat assembly includes: a hat housing and a support tube longitudinally extending through the hat housing a domed shaped endcap and an insulative bushing.

Abstract: A mobile high-frequency antenna rapidly adjustable to minimize VSWR and maximize transmitting and receiving efficiency includes a conductive whip mounted on a coil housing containing a solenoidal loading coil electrically connected at an upper end to the whip and at a lower end to a conductive mast which supports the coil housing. A coil contactor disk at the upper end of a conductive metal shaft raised or lowered by a stepper motor-driven lead screw has protruding spring loaded balls which rollingly contact inner surfaces of coil turns to thus insert less or more inductance between the shaft and whip to tune the antenna. A pair of RF de-couplers in a coil housing base plug which electrically contacts the mast and the lower end of the coil slidably support and electrically contact the shaft, thus shorting out lower parts of the coil to suppress harmonic currents from being induced therein.

Abstract: A mobile high-frequency antenna rapidly adjustable to minimize VSWR and maximize transmitting and receiving efficiency includes a conductive whip mounted on a coil housing containing a solenoidal loading coil electrically connected at an upper end to the whip and at a lower end to a conductive mast which supports the coil housing. A coil contactor disk at the upper end of a conductive metal shaft raised or lowered by a stepper motor-driven lead screw has protruding spring loaded balls which rollingly contact inner surfaces of coil turns to thus insert less or more inductance between the shaft and whip to tune the antenna. A pair of RF de-couplers in a coil housing base plug which electrically contacts the mast and the lower end of the coil slidably support and electrically contact the shaft, thus shorting out lower parts of the coil to suppress harmonic currents from being induced therein.

Abstract: A frequency adjustable radio antenna includes a conductive whip on an insulated cylindrical coil housing electrically connected to the upper end of a tuning coil within the housing. A commutator attached to a conductive shaft is raised/lowered to interpose less/more coil turns between shaft and whip to tune the antenna. An RF de-coupler slidably contacts the shaft, and electrically contacts the lower end of the coil and a conductive mast which supports the housing, thus shorting out lower portions of the coil to suppress harmonic currents from being induced therein. A method for making the coil includes winding wire onto a mandrel in a first direction, sliding a housing over the windings, and rotating the mandrel in an opposite direction to cause coil convolutions in a helical mandrel groove to increase in diameter and thereby spring out of the mandrel groove and into a helical coil housing groove.

Abstract: A frequency adjustable radio antenna attachable to an exterior portion of a motor vehicle has an effective resonant wavelength which may be varied from a remote location; e.g., a transceiver located within the vehicle, to selected values includes a hollow conductive base mast electrically insulated from a mounting bracket and a radio frequency connection to a transceiver, an elongated hollow cylindrical coil housing attached coaxially to the upper end of the base mast and an upper circular cap attached to the upper end of the coil housing in coaxial alignment therewith. The housing is made of an electrically non-conductive material and has formed in inner cylindrical wall surface thereof an elongated helical groove which holds a tuning coil coaxially enclosing a disk-shaped commutator which has a resilient outer surface longitudinally slidably contactable with inner conducting surfaces of convolutions of the coil.

Abstract: A frequency adjustable antenna for transceivers operable at different frequencies, having electrically isolated fixed and extensible mast sections separated by a loading coil in continuity with the fixed mast section and insulated from the extensible mast section and a contactor carried by the extensible mast section commutating with the loading coil for tuning the frequency response of the antenna; and a servo for remote extension and retraction of the extensible mast section selectively positioned thereby.