he Yaesu ATBK-100 is a VHF/UHF Counterpoise Kit for the ATAS 100/120 family of Active Tuning Antenna Systems.

The ATBK-100 fits over a user-supplied antenna mount on the metal handrail of a flat, apartment or townhouse balcony, and it includes counterpoise radials for the 50, 144 and 430MHz Bands, with the balcony railing providing the counterpoise for the HF band. 

Specifications
50MHz Elements 1 & 2 (approx):	Stud, 1cm
Coil, 8.7 cm
Whip, 60cm
144MHz Element, (approx):	60cm
430MHz Element, (approx):	18cm
Mounting Ring (outer diam, approx):	5.4cm
Mounting Ring (inner diam, approx):	3.6cm