Vertical Section and Feedpoint Height in Inverted L EFHW Antennas
A common misconception is that the physical height of the feedpoint defines where radiation starts. Many assume raising the feedpoint raises the footprint, reducing low-angle DX. This intuition is misleading.
Here we clarify the role of feedpoint height vs. radiation height in inverted L EFHW antennas — and why performance is dominated by current distribution, not just the location of the feedpoint.
Radiation Comes From Current, Not Feedpoint Location
Radiation in verticals and inverted Ls originates from current maxima, typically in the lower quarter of a resonant radiator. Moving the feedpoint up or down by 0.5–1 m doesn’t shift the entire pattern — the current distribution along the wire sets the takeoff angle.
Feedpoint Height Affects Impedance, Not Radiation Pattern
Raising or lowering the feedpoint mostly changes impedance and match behaviour, not radiation footprint. The elevation pattern is defined by radiator geometry and ground coupling. If the horizontal section is 15 m up, it hardly matters if the feedpoint is 1 m or 2 m above ground — the current along the radiator dominates.
Ground Loss Is the Real Enemy
Efficiency loss comes from poor ground coupling, not feedpoint height. If the vertical leg is too close to lossy soil without radials or isolation, significant power is burned in the ground. Optimising grounding or raising just enough to fit a choke/counterpoise is far more important.
Inverted L EFHWs Specifically
In EFHW Inverted Ls, the vertical section drives low-angle DX radiation. The horizontal section largely sets feedpoint impedance via capacitive coupling. With a 15 m mast, whether the transformer is at 1 m or 2 m AGL makes little DX difference. What matters is transformer quality, choke placement, and horizontal height.
Conclusion
Feedpoint height affects impedance matching more than radiation footprint. For inverted L EFHWs:
- DX angle comes from vertical current, not base height
- Raising feedpoint can improve match or reduce CMC pickup
- Ground loss dominates efficiency far more than feedpoint location
A higher feedpoint won’t kill your low-angle radiation — but poor grounding will.
Mini-FAQ
- Does feedpoint height affect DX performance? — No. The vertical section’s current sets takeoff angle. Feedpoint height mainly shifts impedance.
- Why raise feedpoint at all? — To ease choke/counterpoise install, reduce CMC, or fine-tune matching — not to change the pattern.
- What most reduces efficiency? — Ground loss. Poor soil coupling wastes more RF than any 1 m difference in feedpoint height.
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