Compact Circularly Polarized Patch Antennas Using 3-D Printed Nonuniform Metal/Dielectric Structure

This letter proposes a kind of 3-D printed patch antenna with compact size and circularly polarized (CP) radiation by using the non-uniform metal or dielectric structure. The conductive filament with low melting point, i.e., Electrifi, and the dual-extruder fused filament fabrication (FFF) process are here utilized to implement the desired metal-dielectric composite structure with high design freedom. Firstly, for reducing the size of the patch structure, metal blind vias are introduced to provide the extra capacitance. Then, based on the compact patch prototype, two different strategies for generating CP waves are proposed where non-uniform metal and dielectric structures are utilized to support the desired perturbation respectively. The non-uniform metal structure is formed by adjusting the initially introduced blind vias with different depths, while the dielectric one is achieved by bringing in air blocks for the asymmetrical dielectric distribution. Compared with those previously reported 3-D printed patch antennas, the proposed one fully utilizes the design freedom offered by 3-D printing. The side length of the proposed 3-D printed CP patch antenna is less than 0.4 λ0, where λ0 is the free-space wavelength of the center operating frequency.