Multiple targets localization using frequency domain data

Multiple frequency domain measurements can be used to localize multiple targets using only two non-directional antennas. In our problem, the target ranges (~30ft) are not much larger than the two antennas separation (~6ft), thus the far field assumption of (d sin θ^k) delay is not very accurate. In this work, we calculate the exact length of the round trip from the transmitter to every receiving antenna without far field approximation. Range estimation is the keyword for the solution of the DOA problem using only two antennas. Bilateration is useful if we have only two antennas, but ambiguity will appear in some cases. However, ambiguity can be eliminated using trilateration (three antennas instead of two). The results shown are just to check the validity of the idea. Accuracy, robustness and reliability of the proposed method still need to be studied in more details.