Lowering Feedpoint, SWR Doesn’t Change on a 160/80 m Inverted-L EFHW

When adjusting an EFHW antenna, many operators expect that raising or lowering the feedpoint — for example, from 1 m to 2 m above ground — will influence the SWR. But what if it doesn’t?

That’s often a good sign. And it says something about your ground quality.

The Setup: 160/80 m Inverted-L EFHW

We’re focusing here on an inverted-L EFHW designed for the low bands:

  • Wire length: 78–82 m total
  • Bands:
    • 160 m: half-wave (1/2λ)
    • 80 m: full-wave (1λ)
  • Feedpoint height: ~1–2 m
  • Matching: 68:1 UNUN + choke

You raise or lower the feedpoint... and the SWR doesn’t really change. Why not?

It Means You Have Good Ground

A 160/80 m EFHW relies on a return current path — typically via the coax shield or a counterpoise — which couples capacitively into the earth. This return path's stability depends heavily on ground quality:

  • Good ground (moist clay, loam):
    • High dielectric constant
    • Low ground loss
    • Capacitive return remains stable
    • Feedpoint height has little effect on SWR
  • Poor ground (dry sand, rocky soil):
    • Low dielectric constant
    • High loss
    • Capacitive return becomes unstable
    • SWR is much more sensitive to feedpoint height, counterpoise layout, and coax effects

In short: your feedpoint doesn't need to be high when the ground is doing its job well.

The Myth: Low Feedpoint = Bad Performance

Many hams assume that a low feedpoint “hurts” radiation. That’s often true for verticals and low-Z antennas. But:

  • In a 160/80 m EFHW, the feedpoint is a voltage maximum and current minimum
  • The majority of radiation comes from higher-current regions further along the wire
  • So raising the feedpoint only slightly affects pattern or efficiency

If the SWR stays steady, you can safely place the matching unit just 1 m above ground — especially for Inverted-Ls on 160 and 80 m.

What You Might Observe

Observation Ground Quality Notes
SWR stable when moving feedpoint Good ground Capacitive return is consistent
SWR shifts when lowering feedpoint Poor ground Return path becomes lossy/unstable
SWR changes with moisture/rain Moderate ground Ground characteristics fluctuate

Practical Tip

For 160/80 m EFHW Inverted-L antennas: a 1 m high feedpoint is fine if you have reasonable ground. If the SWR fluctuates or looks odd with small changes, suspect poor soil and review your common-mode choke and counterpoise setup.

If your SWR doesn’t change much when adjusting the feedpoint height on a 160/80 m EFHW, it likely means your ground quality is decent — and your antenna system is behaving predictably.

Interested in more technical content like this? Subscribe to our notification list — we only send updates when new articles or blogs are published: https://listmonk.rf.guru/subscription/form

Questions or experiences to share? Feel free to contact RF.Guru or join our feedback group!

Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.