Parabolic Reflector Antenna Gain Calculator
Introduction
Microwave systems engineers who need a first-pass dish gain figure for a link budget — before committing to a full path calculation or an EM simulation — get dBi from diameter and frequency in one screen. This calculator estimates antenna directivity using the standard parabolic gain equation G = 10 * log10(efficiency * (pi * D / lambda)^2) with a typical 55% aperture efficiency.
This tool provides a rapid, practical way to evaluate the performance of a parabolic reflector antenna based on its physical dimensions and operating frequency, alongside its aperture efficiency.
How-to
- Type the reflector diameter in meters into the diameter field.
- Type the operating frequency in GHz.
- Leave the aperture efficiency at the pre-filled 55% or enter the efficiency specified for your feed.
- Read the wavelength in meters and the antenna gain in dBi, which update as you type.
FAQ
Q: What is the formula for parabolic reflector antenna gain?
A: G = 10 · log10(η · (πD/λ)²), where D is the reflector diameter, λ = 3×10⁸ / (f in Hz) and η is the aperture efficiency — this calculator evaluates it with a typical 55% efficiency.
Q: What aperture efficiency should I assume for a parabolic dish?
A: This tool pre-fills 55%, a typical aperture efficiency for a parabolic reflector; because gain is linear in η, a dish specified at a different efficiency scales the result proportionally.
Q: Does doubling the dish diameter double the gain?
A: No — gain goes as (πD/λ)², so doubling D adds 20 · log10(2) ≈ 6 dB, not 3 dB.
Q: Can I use this dish gain figure as the final value in a link budget?
A: Only as a preliminary estimate; it is not a substitute for review by a qualified or licensed engineer.