920 MHz Band Magnetic Loop Antenna Buried in the Ground

A small magnetic loop antenna has been studied for underground operation in 920-MHz band considering the application of underground-to-aboveground communications. The antenna has two radiating loops and an excitation loop with the matching capacitors and is buried under the ground. A finite area of the ground is modeled as a lump of soil with a hole where the antenna is placed in the simulation. The reflection and radiation characteristics have been shown and compared with those of a half-wavelength dipole antenna. While the dipole antenna is heavily degraded in the hole of the soil, the magnetic loop antenna is less affected by the soil nearby and radiates towards aboveground.