Cost-Effective 3-D-Printable Polarization Reconfigurable Antenna for Millimeter-Wave Smart IoT Applications

Polarization reconfigurable antennas (PRAs) benefit Internet of Things (IoT) applications as they can adapt their polarization to enhance signal strength, minimize interference, and ensure efficient communication in diverse environments. However, most PRAs in existing literature utilize microstrip technology and PIN diodes for polarization reconfiguration, which perform well at lower frequencies. When adapting these designs for millimeter-wave (mm-wave) frequencies, several challenges arise. Therefore, a novel ferromagnetic-based PRA is introduced in the mm-wave spectrum for smart IoT applications for the first time. Circular polarization (CP) is achieved by creating two perpendicular electric fields (E^x₁₁ and E^y₁₁) by the incidence of the linear polarized fields rotated at an angle of 45° relative to the dual-image-dielectric-guide (DIDG). The antenna incorporates a DIDG supporting both E^x₁₁ and E^y₁₁ modes with identical cut-off frequencies, two ferrite pillboxes (FPs), a matching taper for impedance matching, and a tapered dielectric rod for radiation. The FPs facilitate the polarization control. Each FP interacts with the corresponding propagating mode along its axis, enabling the antenna to reconfigure itself between CP and linear polarization (horizontal or vertical polarization). The degree of interaction depends on the magnetic bias and the distance of the pillbox from the dielectric rod. The proposed technique combines the peculiar attributes of the DIDGs with the ferrite characteristics to develop a novel PRA. The PRA requires a small magnetic bias due to its dependency on the applied magnetic field direction. Moreover, the antenna can be manufactured using only a 3-D printer and copper tape, resulting in a cost-effective production process. Owing to its simple structure, lower cost, and control over polarization, the proposed PRA could be an attractive option for future smart mm-wave IoT systems.