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INFINITE SHEATH HELICAL ANTENNA.
HARVARD UNIV CAMBRIDGE MASS CRUFT LAB
The problem of an infinite sheath helical antenna driven by a ring delta generator is considered. The Fourier transform technique is used to solve this problem. It is found that if the radius of the helix is not too large, beta b 2.4048, where beta 2 pilambda and b is the radius of the helix, the current density far away from the driving point can be decomposed into two terms. The first term is constant in magnitude and its phase velocity is less than the speed of light. It is a slow wave term. The second term dies out as 1z2, where z is the axial distance from the driving point, and has a constant phase velocity of beta. This is the radiation term. Near to the driving point, the logarithmic singularity exists just as in the case of an infinite linear, perfectly conducting dipole antenna. Author
AF19 628 2406