Work out antenna gain and range instantly with clear inputs, formula shown and shareable results.
Range comes from the link budget: transmit power plus both antenna gains minus receiver sensitivity, set against free-space path loss. Antenna gain is free power in both directions, which is why a pair of 9 dBi antennas adds 18 dB — equivalent to a 63-fold increase in transmit power — and why directional links reach far further than omnidirectional ones.
Link budget and range
budget = Tx + Tx gain + Rx gain - sensitivity; FSPL(dB) = 20log10(d_km) + 20log10(f_MHz) + 32.45; solve for distance
Antennas are reciprocal, so a directional antenna concentrates energy on transmit and collects more of it on receive. Both ends contribute their gain to the same budget.
Rarely. It assumes clear line of sight with Fresnel zone clearance and no fade margin. Practical designs reserve 10 to 20 dB of margin for rain, multipath and obstruction.