July 2007 | NTIA Technical Report TR-07-449
Abstract: An investigation of different propagation modeling methods to meet the special requirements of a short-range propagation model with low antenna heights was performed, and has resulted in the development of approaches to be taken to accurately model radio-wave propagation loss for these types of scenarios. The basic requirements for the Short-Range Mobile-to-Mobile Propagation Model include: separation distances between the transmitter and receiver from one meter to two kilometers, a frequency range of 150 MHz to 3000 MHz, and antenna heights of one to three meters for both transmitter and receiver sites. It is necessary to develop alternative methods for accurate predictions of propagation loss to provide a propagation model that will simultaneously meet all of these requirements. This will require special considerations that currently available models do not include in their methods of analysis. Several analytical approaches were investigated to develop propagation loss prediction methods that take all of these considerations into account. Analysis efforts have determined that the development of this model will require the use of mutual-coupling predictions and should also include the effects of the surface wave. Conventional far-field antenna patterns and gain of the antennas may also not be valid at close separation distances, since one antenna may not be in the far field of the other antenna. Analysis efforts have also determined that these issues and effects become more significant for the lower frequencies (900 MHz and below). For low antenna heights the effects of the close proximity between the Earth and the antenna produce a strong interaction between the antenna and the ground. The antenna pattern performance is vastly different than if the antenna were in free space.
Keywords: propagation modeling; mobile communications; antennas; radio-wave propagation; mutual coupling; low antenna heights
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