Electromagnetic radiators in a dielectric cylindrical shell

A simple approximate method is used to calculate the losses and efficiency of simple radiators - vibrators and loops - located inside a cylindrical shell composed of dielectric material with electric properties approximating those of glass. It is assumed that the shell is small in comparison with wavelength, and particular attention is given to the cases of a loop antenna with axes of loop and cylinder coinciding, and of a loop antenna with the axis of the loop perpendicular to that of the cylinder.