Interaction driven artificial magnetic conductor and defected ground structure integrated microstrip antenna for subsurface communication.

Designing compact, high-gain antennas at 400 MHz is challenging due to large size, narrow bandwidth, and low efficiency. This work proposes an interaction-driven Artificial Magnetic Conductor-Defected Ground Structure (AMC-DGS) microstrip antenna for subsurface communication. The design exploits electromagnetic interaction between the slot-type DGS, radiating patch, and AMC surface with spacer layer for performance enhancement. The DGS functions not only for impedance tuning or to attain polarization purity but also as an active radiator, enabling current redistribution and higher order mode perturbation. This interaction, combined with composite superposed mode (CSM) excitation and orthogonal slot radiation, achieves a 400 MHz band (379-419 MHz) with 10.2% bandwidth and 6.5 dBi peak gain. Additionally, a higher-order mode generates a second band at 700 MHz (700-714 MHz) with 2% bandwidth and 6.1 dBi gain. The antenna maintains stable broadside radiation with efficiencies of 98% and 70% at 400 MHz and 700 MHz, respectively. The proposed AMC-DGS antenna provides a compact, dual-band solution for subsurface sensing, Wireless Underground Sensor Networks (WUSN), Internet of Underground Things (IoUT), Ground Penetrating Radar (GPR), and other low-frequency communication systems.