An Integrated Microstrip Miniloop Antenna for Short Range Communications in Ubiquitous AVM

The principles of operation and equivalent circuit of a microstrip miniloop antenna are presented. Two possible uses hereof namely as a wake up and a communication antenna are discussed. An appraisal of performance parameters, the attainable effective height for the former and the path loss for the latter follows. To circumvent the difficulties involved in directly measuring these quantities, an alternative measurement procedure using a GTEM cell is elaborated. In a novel communication philosophy entitled wattless Wake Up, the open-circuit voltage of the structure is passed through a detector and a low-loss cascade of CMOS-FETs to switch on the system. Preliminary pattern and impedance measurements in good agreement with theory and simulation are also presented