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Helical Antenna Calculator

This calculator helps determine the key design parameters of a helical antenna, including its total length, number of turns, spacing, and gain based on frequency and diameter. It’s commonly used in satellite communication, aerospace, and radio telemetry.

Helix Antenna Dimension and Gain Estimator

Input Fields
f
MHz
Operating frequency of the antenna
N
Number of turns in the helix
If enabled, the result will update automatically when you change any value.

Helical Antenna Design Formulas

Formula
$$C = \pi \cdot D$$ $$S = \text{spacing between turns (typically 0.25} \cdot \lambda\text{)}$$ $$L = N \cdot S$$ $$\lambda = \frac{c}{f}$$ $$G = 10 \cdot \log_{10} \left(15 \cdot \left( \frac{C^2 \cdot N}{\lambda^3} \right)\right)$$

Where:

  • $$D$$ = diameter of the helix (m)
  • $$C$$ = circumference (m)
  • $$S$$ = spacing between turns (m)
  • $$N$$ = number of turns
  • $$L$$ = total length of helix (m)
  • $$λ$$ = wavelength (m)
  • $$f$$ = frequency (Hz)
  • $$c$$ = speed of light ≈ $$3 × 10^8 m/s$$
  • $$G$$ = gain (dBi)

These formulas are valid for axial-mode operation (when $$C \approx \lambda$$ and $$S \approx 0.25 \lambda$$).


Helical Antenna – Calculation Example

Given:

  • $$f$$ = 2.4 GHz
  • $$D$$ = 0.05 m
  • $$N$$ = 10

Calculation:

  1. $$\lambda = \frac{3 \cdot 10^8}{2.4 \cdot 10^9} = 0.125~m$$
  2. $$C = \pi \cdot 0.05 ≈ 0.157~m$$
  3. $$S = 0.25 \cdot 0.125 = 0.03125~m$$
  4. $$L = 10 \cdot 0.03125 = 0.3125~m$$
  5. $$G = 10 \cdot \log_{10} \left(15 \cdot \frac{(0.157)^2 \cdot 10}{(0.125)^3} \right)$$
  6. $$= 10 \cdot \log_{10} (15 \cdot \frac{0.0246 \cdot 10}{0.00195})$$
  7. $$= 10 \cdot \log_{10} (1891.5) ≈ 10 \cdot 3.276 = 32.76~\text{dBi}$$


The helical (helix) antenna is ideal for circularly polarized radiation and long-range directional communication. This calculator is used in designing antennas for satellite systems, aerospace telemetry, and UHF/VHF radio. By specifying operating frequency, helix diameter, and number of turns, users can obtain total length, spacing, and estimated gain. It supports fast prototyping and simulation before fabrication.

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