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This EFHW antenna (patterned after one by Steve Ellington N4LQ, with notes by K1RF), if built carefully, will serve you for many years, and at up to 200 watts. The heart and engineering of its design is in its 49:1 impedance matching transformer, or unun (connects an unbalanced
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
Figure 2 shows the complete schematic view of a typical EFHW antenna system. Briefly, the 100pf/2kv cap across the primary of the impedance matching transformer is there to allow better tuning in the 10 meter band. The transformer is a step-up with an impedance ratio of 49:1, and wound on a type 43 toroid core.
4 sie 2020 · This is the page on the End-Fed Half-Wave antenna with a 49:1 transformer. This is a multiband antenna without the need for any tuner (which is the best type of antenna).
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.
• 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.
