  Searches for dark matter axion involve the use of microwave resonant cavities
operating in a strong magnetic field. Detector sensitivity is directly related
to the cavity quality factor, which is limited, however, by the presence of the
external magnetic field. In this paper we present a cavity of novel design
whose quality factor is not affected by a magnetic field. It is based on a
photonic structure by the use of sapphire rods. The quality factor at cryogenic
temperature is in excess of $5 \times 10^5$ for a selected mode.
