Parabolic Dish Antenna
A parabolic reflector focuses energy into a narrow pencil beam whose gain grows with the square of the diameter-to-wavelength ratio. Enter the dish diameter, frequency and aperture efficiency to get the boresight gain, the half-power and first-null beamwidths, and the effective aperture — the essentials for a point-to-point or satellite link.
Equations & Parameters ▸
\(G=\eta\left(\dfrac{\pi D}{\lambda}\right)^2 \qquad \theta_{HPBW}\approx\dfrac{70\lambda}{D}\ (^\circ) \qquad \theta_{FNBW}\approx\dfrac{140\lambda}{D}\ (^\circ)\)
\(A_e=\eta\,\dfrac{\pi D^2}{4} \qquad \lambda=\dfrac{c}{f_0}\)
\(A_e=\eta\,\dfrac{\pi D^2}{4} \qquad \lambda=\dfrac{c}{f_0}\)
| D | Reflector diameter (m). |
| f0 | Frequency (GHz). |
| η | Aperture efficiency (typ. 0.5–0.7). Accounts for illumination taper, spillover and losses. |
| HPBW | Half-power (−3 dB) beamwidth. The 70·λ/D coefficient is typical; it ranges ~58–70 with taper. |
Reference: C. A. Balanis, Antenna Theory: Analysis and Design, 4th ed., Wiley, 2016.
Inputs
m
Dish sizeGHz
Band0.5 – 0.7
Results
Gain
Gain—
Gain (linear)—
Effective aperture Ae—
Beam
Wavelength λ—
Half-power beamwidth—
First-null beamwidth—
Diagram