Abstract
The cell site in certain PCS systems polls the user terminals to determine their needs for system access. Reflections of the high power interrogation signal can mask the presence of the user terminal's response transmission. Circular polarization, which has been used in radar systems to reduce reflections from rain, is considered as a means of reducing the interference caused by reflections of the polling signal. The paper considers the mechanism of this reduction and establishes the requirements for amplitude and phase balance of the two components of linear polarization as a function of the required level of cancellation at the polling antenna. The mechanisms of depolarization of the reflected signal in both natural and man-made environments are considered. Man-made environments can have very large reflections, but generally these reflections have a low level of cross-polarization. Propagation in urban environments is considered to determine how rapidly the environmental reflections decrease as a function of the time delay between the arrival of the polling signal at the user and the transmission of the user's reply.
Published Version
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