ERI’s Rotofiller™ Series ROTOTILLER® FM antenna utilizes variable bay to bay spacing to further reduce downward radiation. As compared with a standard X Series half wave spaced antenna. The Rotofiller series provides reduced vertical plane radiation which helps to comply with FCC regulations for downward radiation. This vertical plane sidelobe reduction to less than -30 dB lessens interference with ground level studio and telecommunications systems. In addition, the possibility of ground reflections that can cause mulitpath interference is reduced. The Rotofiller™ puts radiation where you need it— in the main beam. The Rotofiller Series ROTOTILLER FM Antenna is available in low, medium, and super high power models. Higher power gain (without sidelobe reduction) can be obtained by using ERI’s standard half wave antennas.