Endfed halfwaves (EFHW)

Some years ago I began to experiment with endfed halfwave antennas. My friend Eric WL7CMT suggested many years ago that I experiment with those. As this is an antenna which is a bit off the beaten track, I did not trust it. Then I built one for 20m and was surprised!

The one shown in the video is matched with a low pass, now I built one using a broadband ferrite transformer using two stacked Würth Ferrite cores (2 primary windings, 15 secondary windings, primary compensated with 110pF). The core material is a bit like Material 43

The results are not in yet but I am under the faint impression that the low pass is more efficient than the transformer. Certainly, using a single core drives the same into saturation.  FT140-43 would be the traditional building material.

Another insight was that two primary windings are more suitable for high frequencies than one. It is difficult anyway to get the cap to compensate for the primary inductance. I might add some screenshots of the VNA plots.

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