This tool provides a rough estimate of the maximum potential range for either **tropospheric propagation** (VHF/UHF) or **ionospheric skip** (HF), based on band, time, and solar conditions.

Tropospheric propagation typically occurs during temperature inversions or high-pressure systems and affects VHF/UHF bands. Ducting can enable contacts of 300–1200 km or more.

Ionospheric skip is common on HF bands, where signals are reflected off the ionosphere. Skip distance depends on time of day, band, and solar activity. For example:

• 80m/40m: better at night, regional coverage
• 20m/15m/10m: long-distance DX possible, best during high solar activity

This calculator provides a **best-case propagation distance** — real-world conditions like terrain, noise, antenna height, and polarization can reduce effective range.