Calculator Inputs
Formula Used
1) Wavelength: λ = c / f
2) Half-Power Beamwidth: HPBW ≈ K × (λ / D)
3) First Null Beamwidth: FNBW ≈ 2 × HPBW
4) Beam Solid Angle: ΩA ≈ 1.133 × θE × θH
5) Directivity: D ≈ 4π / ΩA
6) Aperture Gain: G ≈ η × (πD / λ)²
7) Footprint Diameter: Width ≈ 2R × tan(HPBW / 2)
Here, K is the beam constant, D is the aperture or dish diameter, η is efficiency, R is range, and angles for solid-angle work are converted into radians.
How to Use This Calculator
- Enter the operating frequency and choose the correct unit.
- Provide the antenna aperture or dish diameter.
- Select a beam constant that matches your antenna style.
- Set aperture efficiency based on design quality or vendor guidance.
- Adjust the E/H ratio if the beam is not symmetrical.
- Enter range to estimate beam footprint at the target distance.
- Add extra loss if you want a more conservative effective gain.
- Press the calculate button to see results, chart, CSV, and PDF exports.
Example Data Table
| Antenna | Frequency | Aperture | Beam Constant | Efficiency | Approx. HPBW | Approx. Gain |
|---|---|---|---|---|---|---|
| Point-to-Point Dish | 5.8 GHz | 0.60 m | 70 | 65% | 6.03° | 29.04 dBi |
| Backhaul Dish | 11 GHz | 0.30 m | 70 | 60% | 6.36° | 28.08 dBi |
| Compact Horn | 24 GHz | 0.12 m | 58 | 58% | 6.04° | 29.59 dBi |
| Outdoor Panel | 2.4 GHz | 0.22 m | 75 | 55% | 42.58° | 15.18 dBi |
These values are practical approximations. Real antennas vary because of illumination taper, feed geometry, edge spillover, radome effects, and measurement method.
Frequently Asked Questions
1) What does antenna beamwidth mean?
Beamwidth describes how wide the main radiation lobe spreads. The half-power version measures the angle where signal strength drops by 3 dB from peak.
2) Why does a larger dish create a narrower beam?
A larger aperture focuses energy more tightly. When the wavelength stays fixed, increasing diameter reduces HPBW and usually increases directivity and gain.
3) Which beam constant should I choose?
Use a value that matches your antenna style or vendor data. Many dishes use around 70, while some horn estimates are closer to 58.
4) Is this calculator suitable for Wi-Fi and microwave links?
Yes. It works well for fast planning of Wi-Fi bridges, microwave backhaul, panel antennas, horns, and dish-based outdoor networking systems.
5) What is the difference between directivity and gain?
Directivity measures how concentrated the pattern is. Gain includes efficiency and practical losses, so it represents a more realistic system performance figure.
6) Why are E-plane and H-plane beamwidths separate?
Some antennas are not symmetrical. Their vertical and horizontal spreads differ, which changes beam shape, solid angle, and pattern-based directivity estimates.
7) Does beam footprint equal actual coverage quality?
Not exactly. Beam footprint shows geometric spread at range. Actual coverage quality also depends on power, interference, fading, alignment, obstacles, and receiver sensitivity.
8) Are these values exact enough for procurement decisions?
They are useful for planning and comparison. Final procurement should still consider measured manufacturer patterns, gain charts, mounting needs, and regulatory constraints.