A wideband circularly polarized dual-loop antenna based on zirconia ceramic

With the continuous increase of the working frequency of RF system, dielectric antenna has drawn much attention since it would not be affected by conductor loss. This paper proposes a wideband circularly polarized (CP) dualloop dielectric antenna, based on ceramic 3D printing technology and the leakywave radiation of highpermittivity dielectric waveguide operating at the cutoff region of highorder mode. Compared with the wideband CP metal loop antenna similarly working at travelingwave state, the proposed dielectric one generates leakywave radiation more easily. This paper investigates the radiation mechanism of dielectric waveguide and exhibits the design process of proposed dielectric antenna in detail, which is bending the straight dielectric waveguide with leakywave radiation into loop structure to realized circular polarization, and transforming single loop into dualloop structure for wider operational frequency band. It is found that the axial ratio bandwidth of the dualloop antenna is about three times than that of the singleloop one, and both antennas show good righthanded circular polarization in respective working bands. In order to verify the validity of proposed antenna design, an antenna prototype is fabricated by using ceramic vat photopolymerization, i.e., a kind of 3D printing technology. The measured axial ratio bandwidth covers from 3.94 to 5.1GHz, with the maximal radiation gain of 8.6dBic.