The driving quest for greater and greater bandwidth is the reason for migration of cellular communications from microwave to the millimeter wave frequency domain where wider frequency bandwidths are available.
At millimeter wave (frequencies between microwave and optical), quasioptical design techniques are applicable for antennas, radomes and other components. Radomes (specifically, covers over the antennas to protect them from the environment) require new design methodology. Simple A-sandwich or multilayer wall concepts used at microwave frequencies just do not provide the frequency bandwidths required for 5G low loss transmission. Another fact is that some of the common plastic materials used at the lower microwave frequencies are incredibly lossy in the millimeter wave. This occurs for two reasons: (1) millimeter wave radomes are thicker in terms of wavelengths than their microwave counterparts, and (2) variants of so called Debye relaxation (molecular resonances) cause peaks in the loss tangent for many materials. Transmission loss gets large at these resonant frequencies for material where this is a problem.
This presentation will provide a survey of old and recently developed radome materials applicable to 5G microcell radomes , their dielectric parameters (dielectric constant and loss tangent) and a discussion of dielectric measurement techniques for quantification of the dielectric parameters of new material candidates. It will also present an overview of best millimeter wave design procedures and examples of performance achievable.