Antennas and Security

Antenna design is discussed for both short range (<1 m) and long range security applications (1-20 m). To image a person at short range the field of view is 90deg times 45deg and this is often satisfied by rapidly scanning one or more small antennas over this large angle. At stand-off ranges (~20 m) the field of view is decreased to 2deg times 5deg and in this case antennas with scanning systems are used. This scanning can be achieved with electro- optic techniques such as rotating mirrors, or electronic methods which utilise frequency scanning.