The experimental determination of equivalent networks for a coaxial line to helix junction

Equivalent networks were determined for a right angle transition between a coaxial line and a shielded helix. By employing a movable mercury short on the helix it was possible to determine these equivalent circuits through the use of well-known microwave measurement techniques. Utilizing the possible physical connection which might exist between the junction and its equivalent circuit, an attempt was made to measure quantitatively the effect of varying various parameters in the junction. For the limited number of cases studied, no simple connection between the elements of the equivalent circuit and the physical parameters of the junction was discovered. Although the results for the equivalent networks were very sensitive to small experimental errors, by using these networks it was possible to calculate reasonably accurate values of input impedence in the coaxial line for known impedance terminations on the helix.