Mirror-Integrated Dielectric Resonator Antenna

A mirror-integrated dielectric resonator antenna (MIDRA) is proposed. The mirror consists of a glass layer with a very thin light-reflective film coated at its back. It is overlaid on top of a dielectric resonator antenna (DRA), forming a two-layer DRA when the thin light-reflective film is neglected. To allow the wave to penetrate from the DRA to the glass layer, the film is made of nonconducting alternate layers of titanium dioxide (TiO₂) and silicon dioxide (SiO₂) instead of the traditional conducting silver (Ag) or aluminum (Al) coating. To demonstrate the idea, two cylindrical MIDRAs were designed and fabricated. The first one is excited in its TM_01δ mode by axially feeding it with a coaxial probe, giving an omnidirectional radiation pattern. For the second design, the broadside HEM_11δ mode is excited by using a slot-coupled source fed by a microstrip line. Experimental results show that these two MIDRAs radiate effectively as conventional DRAs. Since the proposed antenna appears to be a mirror, it can be an excellent hidden antenna that provides practical mirror functions.