A Wire-Metamaterial-Loaded Resonant Cavity Antenna Using 3-D Printing Technology

Homogeneous dielectric slabs (HDSs) are widely used as the superstrate of resonant cavity antennas (RCAs). For HDS-loaded RCAs, the achievable directivity increases with the relative permittivity (ε,.) of the HDS. Commercial printed circuit boards with removed copper cover are usually used as the HDS superstrate, but their ε,. and thickness are limited in the market. Three-dimensional (3-D) printed HDS has the advantage of fast prototyping, process simplicity, and rigidity and can alleviate the limitation of thickness. However, the low ε,. makes it unattractive in the application of RCA serving the superstrate. In this letter, the wire metamaterial (WMM) with 3-D-printed host dielectric is used as the superstrate of RCA. The effective relative permittivity and effective thickness of the WMM are investigated. It is found that the WMM slab can be equivalent to an HDS with higher ε,. and thinner thickness. To validate the equivalence, the WMM-loaded RCA operating at 14 GHz is simulated, fabricated, and measured. The gain of 12.9 dBi, sidelobe level of -18 dB, and cross polarization of -24 dB have been achieved.