Radiation Resistance of a Helical Antenna in a Compressible Electron Plasma

Abstract

Earlier work on the radiation fields of a travelling-wave helical antenna in a compressible electron plasma has been extended to evolve expressions for the electromagnetic mode component R. and the electroacoustic or plasma mode component Rp of its radiation resistance. These expressions, - which are general in nature but involve complicated integrals, cover the special cases of multiturn loops, circular arcs and linear antennas. Analytical expressions for R. are then derived for the particular example of a helical antenna of small pitch angle with a fractional or integral number of turns. It is found that R. increases with pitch angle for some values of plasma frequency.