Calculator Inputs
Example Data Table
| Scenario | Frequency | Gain | Efficiency | Effective Aperture | Physical Aperture |
|---|---|---|---|---|---|
| ISM dish link | 2.40 GHz | 24.0 dBi | 62% | 0.3119 m² | 0.5031 m² |
| X-band terminal | 10.00 GHz | 35.0 dBi | 58% | 0.2262 m² | 0.3899 m² |
| 5.8 GHz panel | 5.80 GHz | 18.0 dBi | 70% | 0.0134 m² | 0.0192 m² |
| 28 GHz backhaul | 28.00 GHz | 30.0 dBi | 55% | 0.0091 m² | 0.0166 m² |
Formula Used
Wavelength: λ = c / f
Effective aperture from gain: Ae = Gλ² / 4π
Physical aperture from efficiency: Ap = Ae / η
Gain from physical aperture: G = 4πηAp / λ²
Captured power: P = S × Ae
Net values with losses: divide gain and effective aperture by 10L/10
This page also provides approximate beamwidth estimates. Circular apertures use a dish-style relation, while rectangular apertures use separate width and height approximations.
How to Use This Calculator
- Select whether you want to size an antenna from gain or infer gain from physical aperture.
- Enter the operating frequency and the matching unit.
- Set aperture efficiency to reflect spillover, taper, blockage, and conductor losses.
- Choose the aperture shape that best matches your antenna geometry.
- Provide either target gain or the physical dimensions, depending on the selected mode.
- Optionally add power flux density to estimate received capture power.
- Include extra system loss if radome, feed, or implementation losses matter.
- Press the calculate button and review the result panel above the form.
Frequently Asked Questions
1. What is antenna aperture?
Antenna aperture describes how much electromagnetic power an antenna can intercept from an incoming wave. Effective aperture is the useful capture area, while physical aperture is the actual opening size.
2. Why are physical and effective aperture different?
They differ because no antenna converts every part of its opening perfectly. Illumination taper, spillover, blockage, mismatch, and manufacturing limits reduce the useful area below the physical area.
3. How does frequency affect aperture?
At higher frequency, wavelength becomes smaller. For the same gain, the required effective aperture becomes smaller. For the same physical size, gain usually rises as frequency increases.
4. What efficiency should I enter?
Use a realistic engineering estimate. Many practical apertures operate roughly between 50% and 75%, though the true value depends on feed design, taper, losses, and mechanical details.
5. Is the beamwidth result exact?
No. The beamwidth values are quick approximations for early design checks. Precise patterns depend on illumination, polarization, edge taper, shape details, and full-wave electromagnetic analysis.
6. What does captured power represent?
Captured power estimates how much incident power reaches the aperture from a known power flux density. It is useful for link studies, receiving analysis, and sensitivity tradeoffs.
7. When should I use gain-to-aperture mode?
Use it when your design starts from a required gain target. The calculator converts that performance goal into effective and physical aperture requirements for preliminary sizing.
8. When should I use physical-to-gain mode?
Use it when the antenna dimensions are already known. The calculator estimates achievable gain, effective aperture, and receive capability using frequency, efficiency, and optional loss assumptions.