Antenna height calculator
How high does the antenna have to be? Two ways to answer it: Okumura-Hata for macro coverage above 30 m, and ITU-R P.526 clearance for a low antenna that has to clear an obstruction. First-pass numbers for planning, not a substitute for a drive test.
Model and limits
Okumura-Hata: L(d) = 69.55 + 26.16 log f − 13.82 log h_b − 4.92 log d + (1 − 9.2 log d)², with d in km, h_b in m and f in MHz — valid for base-station heights of 30–200 m and distances of 1–10 km. P.526: the first Fresnel radius is r1 = 17.32·√(d1·d2 / (f_GHz·(d1+d2))) with d in km and f in GHz, giving r1 in metres (for a mid-path obstacle the shortcut r1 = 8.657·√(D/f) applies); the antenna must clear the obstruction by v × r1. Both are first-pass estimates — a drive test decides.
Common questions
How do I calculate the height of an antenna for a given coverage distance?
Work backwards from the link budget. The allowed path loss is the transmit EIRP plus both antenna gains, minus the edge level you are designing for, minus your shadow fading margin. Okumura-Hata turns that allowed loss into a base-station height directly. This tool shows the required height and the coverage distance for the height you have actually mounted.
How much does one extra metre of antenna height buy?
In the Okumura-Hata model the path loss falls by 13.82/(h x ln 10) dB per metre, so the gain shrinks as the antenna gets higher: about 0.6 dB per metre at 10 m, 0.2 dB at 30 m and 0.12 dB at 50 m. Above about 50 m, climbing the mast stops being the efficient way to add coverage.
What if my antenna is below 30 metres?
Then the Okumura-Hata height factor is outside its validity range and the numbers become an extrapolation. Below 30 m the obstacle usually decides the link, not the height factor: use the ITU-R P.526 mode in this tool instead, which asks how much Fresnel clearance the antenna needs to clear an obstruction.
Is there a height that will always work?
No. The height that works depends on frequency, transmit power, the edge level you need and the environment. If the required height comes out above 200 m, or the tool reports that the target distance is not reachable at your current height, the answer is more power, a lower band, a sector antenna with more gain, or a repeater site - not a taller mast.
Can this replace a drive test?
No. Both models are planning-grade estimates with stated validity ranges, and the tool tells you when you have left them. Use it to decide between options and to sanity-check a design, then confirm on site with a drive test or a spectrum survey before you commit hardware.
How do I calculate the antenna coverage distance?
Two models, answering different questions. Okumura-Hata turns a link budget into a coverage distance for a mast of 30 m or more, valid out to 10 km. Below 30 m the height usually matters less than the obstruction in the way, and ITU-R P.526 asks how much Fresnel clearance the path needs instead. Use the first for macro coverage, the second for a low antenna behind a building or a ridge.
How is the required antenna mounting height calculated?
Clear the obstruction by v times the first Fresnel radius at the obstacle. Place the obstacle at its real distance d1 from the transmitter, compute F1 there, and require the direct ray to sit v·F1 above it. Measured from the same ground reference at both ends, the transmitting height follows: h_t = (h_obstacle + v·F1 − h_r·d1/d) / (1 − d1/d). The nearer the obstruction sits to the transmitter, the steeper this climbs.