Passive Radar Utilizing Space-Borne Digital Electromagnetic Illuminators

In a passive radar system including at least one space-borne transmitter broadcasting at least one wide-band digitally modulated signal over a region thereby illuminating said region, at least one receiver antenna oriented to receive radiation from at least one portion of said region, wherein said at least one portion is a viewed area viewed by said at least one receiver antenna, and at least one reference antenna oriented toward said at least one space-borne transmitter, wherein said at least one reference antenna receives at least one portion of said at least one wide-band digitally modulated signal, the method comprising the steps of

• (a) selecting a coherent processing time duration based on:
• (i) a radar cross-section of a target within said viewed area
• (ii) a bandwidth of said at least one wide-band digitally modulated signal, and
• (iii) at least one antenna viewing angle of said at least one receiver antenna, wherein said at least one antenna viewing angle is substantially equal to a dimension of said at least one receiver antenna divided by a range to said target;
• and
• (b) coherently processing at least one received signal from said at least one receiver antenna with at least one reference signal from said at least one reference antenna, over a time interval greater than said coherent processing time duration.