  Yttrium Vanadate (YVO4) is a birefringent crystal material used in optical
isolators and circulators with potentials for application in cryogenic
microwave devices. As microwave properties of the YVO4 are not known, we
measured the complex permittivity at the frequency of 25 GHz, using the
Hakki-Coleman dielectric resonator technique in the temperature range from 13 K
to 80 K. The real part of relative permittivity of YVO4 turned out to be
similar to that of Sapphire - one of popular dielectric materials, used at
microwave frequencies. The measured loss tangent tang {\delta} of the YVO4 was
of the order of 10^(-6) at cryogenic temperatures. As Yttrium Vanadate (YVO4)
is easy to synthesis and machine, it may replace the expensive Sapphire in some
microwave applications.
