Low-Probability-of-Intercept/Detect (LPI/LPD) Secure Communications Using Phased-Arrays Employing Side-Lobe Time Modulation

We present an approach for achieving low-probability-of-intercept (LPI) and low-probability-of-detect (LPD) secure communications. The proposed approach uses a phased-array antenna with rapid side-lobe time modulation (SLTM) capabilities. SLTM can be achieved using a conventional phased-array architecture that allows for extremely fast beam forming and shaping. We illustrate the concept using an O-slot patch antenna integrated with two high-speed RF switches for the element of the SLTM array. SLTM is achieved when switched reconfiguring within the phased-array is used to rapidly change the side-lobe shapes and directions with neglectable impact on the main lobe. By pseudorandomly and alternatively controlling the array elements at high speed, the signal radiated from SLTM array is unchanged in the main lobe direction but is covert and entirely distorted along the side-lobe directions.