Secure communications based on directly modulated antenna arrays combined with multi-path

An antenna system configured to provide direction dependent modulation is shown to increase the security of data transmission especially against eavesdropping at directions which are very close to the desired recipient. Such a transmitter system is based on a directly modulated array which can simultaneously send independent signals to multiple spatially separated recipients. In this contribution the performance of an array antenna configured for direction dependent antenna modulation is examined for the case of multi-path transmission. The modulation properties of the directly modulated array system with multipath are compared to those transmitted by an equivalent array with a purely LOS communication link.