Helical Antenna Calculator

About this calculator

An axial-mode helical antenna — a wire wound into a helix, radiating along its own axis rather than perpendicular to it — is prized for producing circularly polarized radiation, which resists signal loss from polarization mismatch and is largely immune to Faraday rotation in the ionosphere. It's the classic antenna choice for satellite communication, GPS ground stations, and deep-space tracking (famously used on NASA's early spacecraft antennas).

Kraus's design equations, used here, size the helix from the operating frequency and number of turns, with the standard turn spacing fixed at 0.25 wavelengths for optimal axial-mode operation: they give the one-wavelength circumference the helix diameter must produce, the total axial length, and the resulting gain, which scales with both the number of turns and the helix circumference.