Helical Antenna

Computes the key parameters of an axial-mode helical antenna including gain, impedance, diameter, coil spacing, wire length, half-power beam width, beam width at first nulls, and effective aperture. Enter either wavelength or frequency — the other is derived automatically.

Inputs

Wavelength(m)

Operating wavelength in metres. If provided, frequency is derived automatically

Frequency(MHz)

Operating frequency in MHz. If provided, wavelength is derived automatically. One of wavelength or frequency must be greater than zero

Number of Turns

Number of turns in the helix

Space Between Coils(wavelength)

Axial spacing between turns as a fraction of wavelength (typically 0.2–0.35 for axial mode)

Results

⚠Enter either wavelength or frequency — one must be greater than zero

Antenna Gain—dBiAntenna gain in dBi

Impedance—ΩInput impedance of the helical antenna in ohms

Diameter—cmHelix diameter in centimetres

Space Between Coils—cmPhysical spacing between turns in centimetres

Length of Wire—cmTotal wire length of the helix in centimetres

Half Power Beam Width—°Half power beam width in degrees

Beam Width First Nulls—°Beam width between first nulls in degrees

Aperture—m²Effective aperture of the antenna in square metres