Propagation considerations on L-band handheld communication service offerings via satellite

The authors discuss a series of experiments attempting to more clearly define the propagation characteristics of L-band signals in various kinds of environments under way at COMSAT Laboratories in Clarksburg, Maryland, USA. The experiments involve taking signal strength measurements of a 1.5 GHz pilot tone aboard an INMARSAT II satellite at 40 degrees elevation relative to Clarksburg. It has been found that wooded areas can produce from 5 to as much as 20 dB of signal attenuation. The human body can also produce up to 10 dB attenuation when blocking the signal path in close proximity to the receive antenna. Studies were also made from inside a building. The average received signal level for a clear direct path through an office window was found to be up to 6 dB less than the equivalent measurement in an outside open area. The window glass seemed to be the main attenuator, with probable interference from scatterers within the office