📶 Parabolic Antenna Gain & Beamwidth Calculator

Gain (dBi) · half-power beamwidth · effective aperture · far-field distance

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Inputs

Results

Antenna gain
– dBi
Half-power beamwidth
– deg
Wavelength
– cm
Effective aperture
– m²
Far-field distance
– m
First-null beamwidth
– deg
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📖 How to use

  1. Pick a preset or enter the dish diameter, frequency and aperture efficiency (0.55–0.65 typical).选预设,或输入口径、频率和口面效率(常取 0.55–0.65)。
  2. Read the gain (dBi), half-power beamwidth, effective aperture and far-field distance.读取增益(dBi)、半功率波束宽度、有效口径和远场距离。
  3. Use the gain value as the Rx/Tx antenna gain in the link budget or G/T tool.把增益值作为链路预算或 G/T 工具里的收/发天线增益。
  4. Arrived via a ↗ link from the Link Budget? Click the return bar at the top to carry the gain straight back into the field you came from (the bar only appears on that round trip, never on a direct visit).如果是点链路预算里的 ↗ 链接跳转而来,点顶部的返回条即可把增益直接带回原字段(返回条只在该往返中出现,直接访问不会显示)。
  5. Mind the pointing note: keep pointing error below ~1/10 of the beamwidth to limit pointing loss.注意指向提示:对准误差应小于约 1/10 波束宽度,以限制指向损耗。

Parabolic antenna equations

Gain: G = η · (π·D / λ)²  →  G(dBi) = 10·log₁₀(G)

Half-power beamwidth: HPBW ≈ 70 · λ / D degrees (uniform-ish illumination)

First-null beamwidth: FNBW ≈ 2.44 · 70 · λ / D ≈ 1.22·... (≈ 2.34 × HPBW for a circular aperture)

Effective aperture: A_eff = η · π·(D/2)²

Far-field (Fraunhofer) distance: R = 2·D² / λ — measure or point beyond this range

where λ = c/f is the wavelength. The narrower the beam, the higher the gain — but also the tighter your pointing accuracy must be. A good rule of thumb is to keep pointing error below ~1/10 of the HPBW to avoid significant pointing loss.

All computation runs locally in your browser.

抛物面天线公式

增益: G = η · (π·D / λ)²  →  G(dBi) = 10·log₁₀(G)

半功率波束宽度: HPBW ≈ 70 · λ / D 度(近似均匀照射)

第一零点波束宽度: FNBW ≈ 2.34 × HPBW(圆口面近似)

有效口径: A_eff = η · π·(D/2)²

远场(夫琅禾费)距离: R = 2·D² / λ —— 测量或对准应在此距离之外

其中 λ = c/f 为波长。波束越窄、增益越高,但对指向精度的要求也越严。一个经验法则是把指向误差控制在约 HPBW 的 1/10 以内,以避免明显的指向损耗。

全部计算在你的浏览器本地完成。