Predicting Propagation Loss from Leaky Coaxial Cable Terminated with an Indoor Antenna

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Abstract

This paper addresses the propagation characteristics of an indoor antenna system consisting of one or more lengths of leaky coaxial cable, each terminated with a 0 dB-gain antenna.

A straight length of coaxial cable with regularly-spaced holes cut in the shielding (aka leaky coax) is treated as a Uniform Line Source antenna. First, a deterministic relation for the path-loss through the air from the nearest point ofthe leaky cable to a half-wave dipole antenna (the coupling loss) is derived Manufacturer’ s data are used to add empirical corrections and “calibrate ” a near field model. A far field modelfor the lossfrom a short, vertically mounted section of leaky coax is also derived. Lossfrom the terminating antenna is modeled using a log-slope equation. A simple way to estimate losses from various wall configurations is suggested. A design methodology for indoor distributed antenna systems is outlined.

Measurements from an indoor antenna system designed using this new model are compared with predictions. After accounting for fading and environmental losses, the mean error was less than 2 dB. The standard deviation of errors was less than 3 dB. Results indicate the model is accurate enoughfor indoor microcell design work.