Enter Antenna Values
Formulas
G = ηD G(dBi) = D(dBi) + 10 log10(η)
D ≈ 4πA / λ² for an aperture estimate
Worked Example
An antenna with 12 dBi directivity and 70% efficiency has approximately 10.45 dBi gain. Loss reduces gain below directivity.
Assumptions and Limits
Efficiency includes conductor, dielectric, and mismatch losses only if your entered value includes them. The aperture mode assumes a uniformly useful physical aperture.
Aperture-based gain is an estimate. Real illumination, blockage, spillover, feed loss, radome loss, and pattern shape can materially reduce gain.