Measurement of complex permittivity of liquid at V band

It is well known that a dielectric constant is essential and has frequency dispersion. So, great numbers of dielectric constant measurement methods have been studied at many frequency bands. Recently, commercial frequency bands have shifted to higher frequency regions. There have been strong demands for a dielectric constant measurement method of a liquid in the millimeters wave region. For that purpose, we gave attention to a free space method, using a lens antenna and measured dielectric constants of ethanol at V band as an example. These results were in good agreement with values measured by a probe method. It was confirmed that the method is effective in permittivity measurement of a liquid in the millimeter wave band.