Radiator
–
Each radial
–
Check with NEC-2
models this ground plane at your height and groundFinds the resonant radiator length, the feed impedance, SWR bandwidth and take-off angle. Takes a few seconds.
Elevation pattern
Same in every directiondBi, rings every 5 dB
SWR on 50 Ω
At the resonant length
Radial field guidance
The classic Brown, Lewis and Epstein measurements, as tabulated in the ARRL Antenna Book: for each radial count, the length beyond which longer radials gain little, and the approximate loss compared with a perfect ground. Rule of thumb; real results depend on your soil.
NEC-2 cannot model radials lying on or buried in the soil, so this tab gives published guidance rather than a model. Expect a feed impedance between about 36 Ω (a very good radial field) and 50–60 Ω (few radials, more ground loss). An “easy” 50 Ω match on a ground-mounted vertical usually means ground loss.
3D view
drag to turn, pinch or scroll to zoom, double-tap to resetLoading the 3D view…
To scale: the antenna, mast and a 1.8 m person. Run the NEC model to add the radiation pattern.
Cut list
Trim to resonance
Measure resonance with an analyser, for example in the Sweep Analyser, then adjust only the radiator.
Quick reference, UK bands
Formula lengths with the current settings. Click a row to design for that band.