RFID : Investigation of selectivity, comparison between active and passive transponders

This is a report where an approach to use a patch antenna as the transmit device when sending radio waves in a RFID system has been investigated. The project is successful in the sense that the antenna is working as imagined, the antenna parameters may however not be satisfactory. The antenna read range may be a little to insufficient when the RFID tags are worn by humans which is one of the underlying requirement for the system this antenna was design for. Tags which are rotated from a vertical alignment also reduce the effectiveness of the antenna even more to a point which is not acceptable. Suggestions for how to further improve the antenna are given and addresses the issues mentioned above. The report first contains a brief introduction to antennas in general and also information about patch antennas specifically as that was the antenna chosen to be constructed and tested for this system as it theoretically seemed very fitting. A working antenna was constructed and tested in a real environment together with simulations of the antenna to further examine it. The finished antenna is evaluated with possible advantages and drawbacks being discussed together with mentioning how then antenna could be improved for better performance