| 摘要 |
The present invention relates to a slot antenna concealed in a vehicle for communicating the vehicle location to a base tracking station. There is a risk that criminals may evade the security measures by finding and removing the antenna. Therefore the slot antenna 9 is concealed inside a lamp unit enclosure 16. In the main embodiment the slot antenna 9 is behind an optical reflector 14 of the lamp unit and the optical reflector comprises portions of electrically conducted material which are electrically isolated from each other so as to limit conduction of electric currents in the optical reflector. This may be by way of a metallic paint with an electrically insulating binding medium or a plurality of separate conducting panels mounted on an insulating substrate. The use of a tuned resonator 17 to reflect the back-directed signal from the slot antenna 9 is also disclosed. Another embodiment relates to a plurality of LEDs 21 aligned with the slot a 19 of a slot antenna 20. As the slot antenna is positioned in the lamp unit, it cannot be screened without conspicuously covering the lamp and making night driving impossible. <IMAGE> |
