The Air Core bifilar Dual Core BALUN is the Guanella 4:1 current BALUN. Designed to handle full legal power with a low standing wave radio (SWR). It has 4 to 1 impedance ratio. Two transmission lines are connected in parallel at the low impedance side and in series at the high impedance end. Making for a more balanced and favorable match. The Air core BALUN wont saturate like the ferrite-core and, unlike ferrite-core wire-wound BALUNs, single-layer wound BALUNs almost never have insulation breakdown problems. This BALUN is rated for Full legal power.
Frequency Coverage: 1.8 to 30 MHz. Good for matching a 200 ohm load to a 50 ohm load, or 300 ohm load to a 75 ohm load. A 4:1 BALUN is a good match for feeding an Off-Center-Fed antenna and performs well feeding an open wire transmission line.