Advanced Dish Gain Calculator

Dish and System Inputs

Use basic fields first, then refine losses and system performance.

Main calculation

Calculation mode

Aperture shape

Electromagnetic input

Primary dimension

Diameter for a circular dish.

Secondary dimension

Minor diameter or aperture height.

Aperture efficiency

Operating frequency

Operating wavelength

Target gain

dBi

Used by reverse-solving modes.

HPBW coefficient

Common values are approximately 58 to 72.

First-null coefficient

Beam spot distance

Gain mode accepts circular, elliptical, or rectangular apertures. Reverse diameter mode returns an equivalent circular dish.

Surface accuracy and antenna losses

RMS surface error

Illumination loss

Spillover loss

Blockage loss

Ohmic loss

Dielectric loss

Radome loss

Polarization mismatch

Impedance mismatch

Receive cable loss

Connector loss

Atmospheric loss

Rain attenuation

Ice, snow, or water loss

Pointing-loss model

Pointing calculation

Manual pointing loss

Azimuth error

Elevation error

Mount accuracy

Wind deflection

Tracking error

Reflector geometry and feed

Geometry calculation

Dish depth

Focal length

Feed configuration

Offset angle

Paraboloid geometry uses f = D²/(16d). Non-circular apertures use the equivalent circular diameter for this estimate.

Transmitter, EIRP, and field calculations

Transmitter power

Additional amplifier gain

Duty cycle

Transmit feedline loss

Transmit connector loss

Evaluation distance

Power density and field strength use a far-field free-space approximation. Verify local exposure and licensing rules separately.

Receiver and G/T

Antenna noise temperature

LNA noise temperature

LNA noise figure

A value above zero overrides LNA temperature.

LNA gain

Receiver noise temperature

Feed loss before LNA

Noise bandwidth

Received signal power

Required C/N or SNR

Comparison dish

Comparison mode

Comparison diameter

Comparison frequency

Comparison efficiency

Comparison surface error

Frequency sweep

Minimum frequency

Maximum frequency

Sweep unit

Sweep points

Inputs are processed on this page. No database is required.

Recent calculations

No saved calculations yet.

Formula guide and assumptions

Core gain equation

G = η(4πA/λ²), and GdBi = 10log10(G)

For a circular reflector, A = πD²/4. The calculator uses actual aperture area for elliptical and rectangular entries.

Surface accuracy

ηRuze = exp[−(4πσ/λ)²]

Ruze loss is an estimate for random RMS surface errors. Structured distortion may behave differently.

Beamwidth

HPBW ≈ Kλ/D degrees

The selected coefficient represents feed taper and illumination. Equivalent diameter is used for non-circular apertures.

Pointing loss

Lp ≈ 12(θerror/HPBW)² dB

This near-boresight approximation is useful for planning. Measured antenna patterns provide better results.

System figures

EIRP = Pantenna + G
G/T = Greceive − 10log10(Tsystem)

Noise calculations use Boltzmann’s constant and the entered equivalent system temperatures.

How to use this calculator

Select gain, diameter, frequency, or efficiency calculation mode.
Enter the aperture shape, dimensions, frequency, and efficiency.
Add surface accuracy, blockage, pointing, and environmental losses.
Enter geometry, transmitter, and receiver values when required.
Enable dish comparison or a frequency sweep for design analysis.
Press the calculation button. Results appear above the form.