The 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.