The performance of an ultra-high-frequency RF identification (ID) system operating at 869 MHz, intended for the ID of persons in both indoor and open areas, has been validated using the propagation models, as well as the series of practical measurements. A two-ray propagation model and the 3-D ray-tracing model were used for calculations of all important system parameters in open and indoor areas, respectively. For the application mentioned above, a novel (electrically small and, at the same time, low-profile) wearable TAG antenna was designed.
It was used in order to carry out the necessary tests as well. The antenna in question is based on an artificial-like surface. The latter provides an important screening effect and avoids detuning. Another virtue of the surface used is represented by the fact that it ensures the minimum loss of the antenna efficiency (resulting from the presence of a nearby human body). The simulations and measurements show that the optimized system can guarantee a reliable ID at distances up to 9 m in open areas and up to 16 m in corridors.Index Terms-Artificial surface, electrically small antenna, identification (ID) of people, loop antenna, RF identification (RFID) system, TAG antenna.
A novel monitoring system for the detection and localization of mobile (cellular) phones in large buildings based on a matrix of microwave sensors has been designed and practically employed. The system enables detection of all active mobile services and ensures very high immunity against all other radio signals. The designed antennas, system structure, and signal processing provide high probability of correct localization of the transmitting mobile phone. Thus far, microwave detection systems with several thousands of sensors have been installed and successfully operated in several prisons in the Czech Republic. The system has been found to be an efficient tool for improving security in highly guarded areas.
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