Numerical analysis of microwave heat generation in disc-shaped Luneberg lenses

An analysis of the temperature field resulting from microwave absorption in an ideal surface-focus disc-shaped Luneberg lens of foamed glass has been performed. Temperature and spatial dependence of both thermal and electrical properties have been taken into account, and two types of convection boundary conditions have been utilised to describe the actual lens behaviour. Calculations indicate that the maximum lens temperature occurs at about 0.1R in from the focal point, and that about 10 kW can be handled by the 0.305 m-diameter 0.635 cm-thick lens without exceeding the thermal capability of the material. Less than 1% of incident power is absorbed by the lens.