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An 80-10 end-fed half-wave antenna can be a very good performing part of an HF station. But its performance depends heavily on a well-designed and carefully constructed 49:1 unun, which matches the long wire impedance to within tuning range of operation. But the perfor-mance of an end-fed antenna is also very dependent on height above ground.
This project assembles a 49:1 ferrite-core (“FT”) type #43 transformer that matches 50 ohm input to 2500 ohm end fed antenna. It is optimized for 3.5/7/10/14 MHz but will work reasonably well on all amateur bands from 80 meters thru 10 meters with a 135 foot length of wire and a short connection to ground.
Detailed Build Instructions for the 80-10 end-fed half-wave antenna with 49:1 unun: Noji-Article-80-10-EF-HW.pdf Source: https://noji.com/hamradio/pdf-ppt/noji/Noji-Article-80-10-EF-HW.pdf
Attach a 2400 ohm resistor between the antenna wire and ground, and test using a SWR meter. SWR should be under 1.5:1. Alternatively, set up a half-wavelength wire outside and connect the matching unit with an antenna analyzer.
Download The Mini 49:1 UNUN Instruction manual here. Antenna wire lenghts. The End Fed Half Wave antenna requires to cut one of halfwave lenghts.
• All antennas need to be as far as possible from ground, antennas, wires, homes and similar. • All antennas become more efficient when farther from ground or adjacent objects. • All antennas behave differently at different locations and in different configurations.
The design used here is taken from Tom Rauch W8JI, a very respected authority on amateur antennas. This G5RV design is intended to support the 80-, 40-, 20-, and 15-meter bands, but requires a tuner, due to excessively low DC resistances at resonance.
