Spiral antenna
A spiral antenna is a planar logarithmic antenna and consists of one or more conductors wound in a spiral shape in one plane , the radius of curvature and effective cross-section increasing from the inside out. Spiral antennas are very broadband, bandwidths from 1 GHz to 20 GHz are common and they generate a circularly polarized electromagnetic wave .
A two-armed spiral antenna consists of two such conductors, which are usually designed as strip conductors . The feed point is formed by the inner ends of the strip conductors. In contrast to helical antennas, helical antennas radiate in both directions perpendicular to the spiral plane.
Mixed forms of spiral and helical antennas are conical or spherical dome-shaped bodies covered with wound strip conductors. Like spiral antennas, these are very broadband, but radiate in only one direction. Spiral antennas are used in avionics , military technology , space probes and in telemetry .
literature
- John D. Kraus: Antennas . 2nd (6th reprint) edition. Tata McGraw-Hill, 1997, ISBN 0-07-463219-1 , Chapter 15 - Broadband and Frequency-Independent Antennas.
- Communication technology part 1 Basics of radio frequency. 1st edition. Institute for the Development of Modern Teaching Methods e. V., Bremen 1980.