GENERATION OF PLANE-WAVES

A method of finding the parameters of spherical horn waveguide capable of generation of plane wave at its open end, is presented. The field functions in this case are expressed in terms of associated Legendre a nd Spherical Hankel function of non-integer parameter. The order of Sp herical Hankel function for a particular combination of flare angles o f horn, is determined from the solution of transcendental equation exp ressed in terms of associated Legendre function of non-integral parame ters. The radial dimension, for which the wave impedance approaches th at of free space, thereby satisfying plane wave condition at the mouth of horn, is then determined. The generation of numerical data involve s the computation of Spherical Hankel and Legendre, since these are no t available in standard tables.