The interest for indoor real time localization systems is growing. There is large potential for new reliable and high resolution systems based on passive, small-size and maintenance free identifiers (tags). This paper presents a new passive tag antenna for a possible hybrid system operating simultaneously in two distinct bands, UHF-RFID and UWB. Such systems can benefit both from the typical range of UHF RFID systems and from the high position accuracy associated with UWB impulse radio. The tag antenna is based on a simple and compact double layer printed configuration.