Dispersion Diagram of a Helical Antenna

A majority of textbooks on antennas neglect to show the use of the dispersion diagram in explaining the properties of a helical antenna. This short paper shows that the region of operation of an axial-mode helical antenna can be easily located on the dispersion diagram. The close relationship between the dispersion diagram as evaluated by Klock and the theory of operation of the helical antenna given earlier by Kraus is also demonstrated.