📡 Line of Sight

Radio horizon distance (miles). Formula: 1.23 × (√h₁ + √h₂), heights in feet.

📏 Antenna Wire Lengths

½-wave dipole ≈ 468/f ft · ¼-wave ≈ 234/f ft · Full-wave loop ≈ 1005/f ft.

Cut a little long and prune for best SWR.

〰️ Wavelength & Frequency

λ (m) = 300 / f (MHz)

📶 Coax / Feedline Loss

Approximate loss for common cables. Real cables vary — check manufacturer data for critical links.

📊 SWR → Return Loss

Convert SWR to reflected power percentage and return loss.

⚡ Power & dB

Watts ↔ dBm and gain/loss.

🔋 Battery Runtime

Estimate hours from capacity and average current draw.

🗺️ Maidenhead Grid

Lat/Lon → 6-character grid. Blackpool / Fylde ≈ IO83.

🔌 Ohm’s Law & Power

Enter any two of V, I, R, P.

··· — Morse Code

Text ↔ Morse. Space between letters, / between words.

📐 Length Units

Feet ↔ metres ↔ inches for wire and coax.