The F-3980 is a wide band dual antenna with an 871F-70 on the base and a 792-70 on the top. The antenna offers for the 871F-70 a choice of radiation patterns that are determined by the dipole-to-mast spacing. The F-3980 has an internal cabling and is not field adjustable. The 871F-70 antenna is offered in a ¼, 3/8, or ½ wave pattern spacing versions. SPEC Sheet