Sirio Antenna Sirio Vector 4000 27-28.5 Tunable Base Antenna Base station antenna omnidirectional tunable by whip length adjusting high power handling capability Type: 3/4 coaxial J-pole Frequency range: tunable from 27 to 28.5 MHz Bandwidth @ SWR 2: 1400 KHz SWR @ res. freq.: 1.2 Max