Round dipole design</br>360?? pick up pattern</br>Multiple units may be stacked vertically for increased signal gain</br>Heavy duty construction with rugged mast clamp and associated hardware</br>Frequency range: 87.5 ~ 108Mhz ?Maximum gain: 4dB ?Impedance: 75ohm?? female " connector ?Diameter: 17.75"</br></br>Product Description</br></br>Rugged outdoor antenna is designed to provide outstanding reception for all broadcast FM stations including HD radio. Fully assembled?? this antenna is ready for immediate installation on an existing mast pipe or in the attic.</br><br/>http://www.amazon.com/gp/product/B00DHHOZBInn