The AS-3900A/VRC is a broadband vehicular whip antenna system designed for use with the U.S. Army’s SINCGARS secure radio system. It provides VHF communication for a range of military vehicles and can be used with any frequency agile radio that operates within its 30-88 MHz frequency band. This antenna can also be used as a direct replacement for the AS-1729/VRC and AS-3684/VRC antenna systems.
Incorporated into the AS-3900A/VRC is a newly designed heat sink to accommodate the high transmitting power level of 150 W with a maximum VSWR of 3.5:1 over the frequency band. The antenna system gain varies from -7-to -1 dB over the operating band relative to a resonant quarter-wave monopole. The complete antenna system is comprised of a two piece whip antenna and an impedance matching base unit. The antenna portion is made up of an upper whip (A3017901-2 Antenna Element - Top Section) and a lower section (A3018230-1 Antenna Element - Center Section) which are assembled by screwing together by hand. The assembled antenna portion is then screwed onto the rugged spring of the base matching unit (A3017902-2 Antenna Subassembly - Insulator/Adapter) to complete the system.
The AS-3900A/VRC is a center fed antenna system. The lower antenna whip section acts as a transmission line to apply the input (X power to a point near the middle of the antenna.) This approach complements the impedance matching function of the base unit to provide the antenna with its broadband operating characteristic without the need of a ground plane.
EMP (electromagnetic pulse) and high voltage protection are also incorporated into the AS-3900A/VRC . An integral high voltage blocking capacitor in the upper whip section provides high voltage isolation to 20 kVrms. This results in increased safety to personnel and equipment in the case of an accidental strike of the antenna to an overhead power line. A molded neoprene rubber eye protection device at the tip of the antenna provides further safety to the user.