HB3YAQLucerne
Locator, distance & bearing
Compare Maidenhead grid centres on a map.
HB3YAQ · Ajdin HadzicLearning to take awayhttps://hb3yaq.ch/en/tools/locator
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Formula & context
a = sin²(Δφ/2) + cosφ₁ cosφ₂ sin²(Δλ/2); d = 2R asin√a
Four- or six-character Maidenhead grids describe areas. The calculation uses their centres and a mean Earth radius of 6371.0088 km.
A worked example
JN47db and IO91wm are approximately 790 km apart. Plotted points are grid centres, not home addresses.
Assumptions & limits
Great circle on a sphere; bearing is initial. It describes neither terrain nor an actual radio path. Direction is undefined for identical or antipodal points.
Maidenhead locator, distance and directionUnderstand the reasoning →From reading to experimenting
Locator, distance & bearing
JN47db and IO91wm are approximately 790 km apart. Plotted points are grid centres, not home addresses.
Open example with starting values →JN47db → IO91wmBack to the learning article →Then change exactly one value. Compare the result and use the formula to explain why it changes. The model limits below the calculator also apply here.