Calculator Inputs
Enter dish size, frequency, aperture efficiency, losses, power, and target gain.
Example Data Table
These sample values show how dish size, frequency, and efficiency affect antenna gain.
| Diameter | Frequency | Efficiency | Loss | Approx Net Gain |
|---|---|---|---|---|
| 0.6 m | 6 GHz | 60% | 0.8 dB | 35.7 dBi |
| 1.2 m | 10 GHz | 65% | 0.8 dB | 42.2 dBi |
| 2.4 m | 14 GHz | 68% | 1.0 dB | 51.0 dBi |
Formula Used
The calculator uses the standard parabolic dish antenna gain equation:
G = η × (πD / λ)²
Gain dBi = 10 × log10(G)
λ = c / f
Net gain dBi = Gross gain dBi - Total losses
Effective aperture = η × πD² / 4
3 dB beamwidth ≈ 70 × λ / D degrees
Here, η is aperture efficiency, D is dish diameter, λ is wavelength, c is light speed, and f is frequency.
How to Use This Calculator
- Enter the parabolic dish diameter and select its unit.
- Enter operating frequency and select the matching frequency unit.
- Add aperture efficiency as a percentage.
- Enter feed, pointing, and polarization losses in decibels.
- Add transmit power if EIRP is needed.
- Enter a target gain to compare the design margin.
- Press the calculate button to show results above the form.
- Use the CSV or PDF button to save the calculated report.
Parabolic Antenna Gain Guide
Why Dish Gain Matters
Parabolic antennas are used when a radio link needs high directivity. The curved reflector focuses energy toward one direction. This creates stronger signal strength than an omnidirectional antenna. Gain is usually shown in dBi. A higher dBi value means the antenna concentrates power more tightly.
Main Design Inputs
The most important inputs are diameter, frequency, and efficiency. A larger dish gives more aperture area. A higher frequency gives a shorter wavelength. Both changes usually increase gain. Efficiency reduces ideal gain because real reflectors have surface errors, blockage, feed mismatch, and spillover.
Losses and Real Performance
Real systems also include feed loss, pointing loss, and polarization loss. These losses reduce usable gain. A perfect calculation may look strong on paper. Field performance may be weaker when cables, connectors, alignment, and weather are considered. This calculator separates gross gain from net gain, so the design is easier to review.
Beamwidth and Alignment
Beamwidth is important for installation. A narrow beam can increase link range. It also makes alignment more sensitive. Small pointing errors can reduce signal strength. The 3 dB beamwidth estimate helps installers understand how accurately the antenna must be aimed.
Using Results in Link Planning
The EIRP output combines transmit power with net antenna gain. It helps estimate radiated strength from the antenna system. The effective aperture value shows how much useful collecting area the antenna provides. The target gain margin helps compare the current design against a required gain. When the margin is negative, a larger dish, higher efficiency, lower loss, or higher frequency may be needed.
FAQs
1. What is parabolic antenna gain?
It is the signal concentration produced by a dish reflector. It compares the focused antenna radiation to an ideal isotropic radiator.
2. Why does frequency affect dish gain?
Higher frequency means shorter wavelength. For the same dish diameter, shorter wavelength increases the ratio between dish size and wavelength.
3. What efficiency value should I use?
Many practical dishes use 55% to 70%. High quality systems may be higher. Poor feed design or blockage can lower efficiency.
4. What is net gain?
Net gain is gross calculated gain after subtracting practical losses. It better reflects the gain available in a working system.
5. What is 3 dB beamwidth?
It is the approximate angular width where antenna power falls to half of the peak value. It helps estimate pointing accuracy.
6. What is effective aperture?
Effective aperture is the useful collecting area of the antenna. It depends on physical area and aperture efficiency.
7. What does EIRP mean?
EIRP means effective isotropic radiated power. It combines transmitter power and net antenna gain into one radiated power value.
8. Can this calculator replace field testing?
No. It gives engineering estimates. Final performance should be checked with real alignment, cable measurements, and link testing.