Design of a Self-Quadruplexing Substrate Integrated Waveguide Antenna for IoT Applications

The expansion of IoT applications in smart grids, precision agriculture, intelligent homes, and transportation systems continues to fuel demand for wireless infrastructure. However, their implementation demands tailored solutions to address evolving user needs, component miniaturization, and system complexity. To address these challenges, this study proposes a four-port self-quadruplexing substrate integrated waveguide (SQ-SIW) antenna. The design was rigorously analyzed through comprehensive simulations and experimental validation, achieving reflection coefficients of -10.13 dB (Port 1), -12.1 dB (Port 2), -10.2 dB (Port 3), and -19.86 dB (Port 4). Notably, the orthogonal port configuration enables simultaneous resonance, enhancing both reconfigurability and operational flexibility. This work establishes a new paradigm for multifunctional IoT antennas, offering scalable solutions for spectrum-constrained wireless systems through its unique combination of spatial diversity and frequency-selective characteristics.