An experimental two element array configured for directional antenna modulation

A two element array configured for direction dependent modulation is investigated. Theoretical models are used to show how the system can be configured to transmit various levels of QAM modulated signals in different directions. In particular we present results to show that the system can transmit 16 level QAM in a given direction while simultaneously transmitting 8 level QAM in another direction. Examples of direction dependent data transmission error rates are examined for specific configurations. Details of a prototype experimental system operating at X-band and implemented using 4-bit digital phase shifters are presented. Measured data are presented to verify the operation of the experimental system.