EFHW Vertical Antenna
Build a G0KYA HF End-Fed Half-Wave Vertical Antenna for DX
Description
Constructing an HF End-Fed Half-Wave (EFHW) vertical antenna, the resource details the winding of a monoband matching unit, inspired by AA5TB, designed to provide a 50 Ohm impedance match without a ground plane or antenna tuner. It specifies the use of a T200-2 ferrite core for the transformer, outlining the 13-turn secondary and 2-turn primary winding process with enamelled copper wire. The document also describes the integration of a coax capacitor, whose length is critical for tuning and varies by band, with specific starting lengths provided for 20m, 17m, 15m, 12m, and 10m operation.
The practical application section guides the builder through tuning the antenna using an antenna analyzer, emphasizing the iterative process of spacing secondary windings and trimming the coax capacitor to achieve resonance at the desired band frequency. It highlights the antenna's low angle of radiation, beneficial for DX, and claims up to 2 S-points improvement over a G5RV or similar doublet when used as an omnidirectional vertical. A comprehensive shopping list, including specific part numbers from Rapid Electronics, is provided, along with advice on selecting fiberglass fishing poles for support and suitable antenna wire.