An approximate method for analysis of azimuthally magnetized circular ferrite waveguide phase shifter

A theorem for the identity of purely imaginary zeros of a certain complex Kummer function Phi(a, c; x) in x and of the real ones of a specific real Kummer function in x is proved numerically provided the imaginary part k of the first parameter of the complex function and the first one of the real function get large negative. Employing this theorem and some known Tricomi formulae, an expression is derived for approximate evaluation of the numbers L(c,n) (the limits of the product of modulus of k and of the imaginary zeros mentioned under the condition stated) by the zeros of definite Bessel functions. Using the expression in question and the assumption for independence of the A, B, C numbers, appearing in the theory of azimuthally magnetized circular ferrite waveguide phase shifters, of given structure parameters, a simple method is developed for reckoning the differential phase shift produced which brings in an error less than one percent.