Proceedings with Extended Abstracts (single PDF file) - Radio ...

• All the costs of transmitter procurement and operation are eliminated.• A passive system requires no license.• A passive system is inherently much safer than an active radar.• A passive system requires little electric power.• A passive system may require a large antenna, but the antenna neednot bear high power, and needs no T/R switch.• A passive system naturally accomodates unattended operation.1.3 Aerospace DevelopmentPassive radars are naturally stealthy, and their relatively long wavelengthoffers potential utility in detection of low-observable targets. Thus, aerospacefirms and military agencies have been investigating passive radar for manyyears; it is only in recent years that these efforts have begun to appear inopen literature. See Howland [1995] and Griffiths et al. [1992] for priorart in aerospace applications of passive radar, and Port [2003] and Leavitt[1999] for aerospace applications of passive radars in news reports. In thecommercial aerospace arena, commercial products are nearing the marketfrom Lockheed Martin Mission Systems (Silent Sentry TM ) and Roke ManorResearch Ltd. (CELLDAR TM ).2 Manastash Ridge Radar OperationsThe Manastash Ridge Radar consists of two identical receiver systems whichare separated by 150 km and the Cascade Mountains (∼ 2000 m). One receiverat the UW gathers the direct broadcast from transmitters illuminatingthe Seattle area; the second but otherwise identical receiver is significantlyshielded from the transmitter by the mountains, and is exposed to signalsscattered back from the upper atmosphere.A matched filter-based signal processor yields range-Doppler profiles likethose in Fig. 1. The scatter receiver can collect signals on several antennas.When the 16 λ baseline antennas are interferometrically analyzed, thescattering region can be distributed in azimuth as well as range, as in Fig. 2.473