October 1969 | NTIA Technical Memo ERL TM ITS 206

UHF Buried Antenna Path Loss Measurements

Larry G. Hause; F. George Kimmett

Abstract: Ground-to-ground path loss measurements are tabulated and discussed for paths terminated in surface and buried antennas, with and without security fences. Both horizontally and vertically polarized antennas at 415.9 MHz were used. Path lengths varied from 15 m to 17 km, and depths ranged from 0 to -2.25 m. Conical pits 3 m deep were dug into the earth and filled with fuel oil, which served as a homogeneous dielectric surrounding the antennas and formed a smooth, level boundary layer at the surface. For low antennas, off-path terrain reflections can be the dominant mechanism in rough terrain. The probability of this increases as antenna height above ground decreases. Only antennas having mainly upward-directed patterns should be used in the buried antenna configura­tion in the 230-400 MHz band. Annular slot antennas 1 m below the surface have transmission loss about 20 dB greater than monopoles 0.75 m above ground. Transmission loss between annular slot antennas increases by 6 dB for each meter increase in depth.

Keywords: buried antennas; path loss measurements; boundary layer; security fences

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Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

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