Amateur Radio Digital Communications (ARDC) is a nonprofit organization dedicated to advancing research, innovation, and education in amateur radio and digital communication technologies. ARDC manages the 44Net (AMPRNet) address space and provides funding for projects that enhance wireless communication, open-source networking, and STEM education.

Our project has been generously supported by ARDC, enabling us to explore and develop cutting-edge solutions in design and experimental evaluation of EBG-Based full-duplex antennas for 400 MHz amateur bands.

We proposes a full-duplex (FD) antenna design with passive self-interference (SI) suppression for the 425 MHz (70 cm) amateur band. The reduction in SI is achieved through using separate transmit (Tx) and receive (Rx) antennas and embedding Electromagnetic Band Gap structures (EBGs) in between the antennas. The antennas are composed of patches made of copper taped over dielectric material, which also contains EBGs. We present the design, optimization, and prototyping of unit antenna elements, EBGs, and integration of EBGs in between the antenna elements. We also evaluate the design through both HFSS (High Frequency Structure Simulator) and over-the-air (OTA) measurements in an anechoic chamber as well as an indoor environment.