A Variable Aspect Ratio Tapered Slot Antenna For Extended Low Frequency Response. The carbon-based diazeniumdiolated molecules release NO spontaneously under physiological conditions without subsequent nitrosamine formation. A second detector detects a positional signal received from the transponder that is decoupled from the first signal and contains precise positional information. Once the scrambler sequence andor encryption sequence is selected, the packet is transmitted using the selected scrambler and encryption sequences.