Ham Radio School — Screwdriver Antenna SWR Analyzer HF Mobile Vertical  ·  80m – 10m  ·  Variable coil position · Quarter-wave over perfect ground
Resonant freq
2:1 SWR BW
Feedpoint Rr
SWR @ resonance
Inductance
Element length 2.00 m
0.5 – 3.0 m  ·  typical mobile: 1.5 – 2.5 m
Coil position 25%
0 = base · 0.5 = center  ·  drag ◀ on antenna
Wiper / turn count
T  (0–300)
Drag ▶ wiper on antenna or use above
Band presets
Sets element length, coil position, and turn count for band center. Tune wiper to fine-adjust resonance within the band.
Spoked disk at tip. Raises Rr by extending effective electrical length. Best on 30m and below.
Lossless L-network at feedpoint. Matches Rr→50 Ω at resonance. Shows transceiver-side SWR.
Zoom ±2.0 MHz Chart follows resonant frequency · all HF amateur bands shaded