Design and performance comparison of compact resonant cavity antennas using customized 3D printing techniques

The Far-field radiation performance of quintessen-tial compact resonant cavity antennas (CRCAs) is compromised because of even transmission through uniform superstrate resulting in non-uniform aperture phase distribution. Phase varying superstrate (PVS) can be used to improve uniformity in aperture phase distribution and hence attain wideband directional performance of CRCAs with small footprint. This paper demon-strates customization ability of additive manufacturing (AM) by designing three PVSs for CRCA using distinct fabrication approaches. The printing methodologies are based on height variation, infill variation, and perforation size variation in the RF graded acrylo-butadiene styrene (ABS) material. Each PVS comprises three dielectric regions with non-identical electrical propoerties to locally vary input phase of antenna. Uneven transmission through PVSs remarkably improves the aperture phase error of CRCAs, and achieves high-directivity (> 17 dB) and wide bandwidth (>50%) with a small footprint of approx 0.84lambda_{L} in diameter at the lowest operating frequency.