Millimeter wave imaging systems and methods using direct conversion receivers and/or modulation techniques

An imaging system comprising:

• an illumination system comprising:
• a carrier wave source configured to generate a radio frequency signal;
• at least one modulator, coupled to the carrier wave source and configured to modulate the radio frequency signal using digital symbols to provide illumination signals;
• and
• a plurality of antennas coupled to respective ones of the at least one modulator and configured to illuminate a scene with the illumination signals;
• a direct conversion receiver configured to receive energy from a scattered illumination signal resulting in part from scattering of the illumination signals from the scene;
• and
• an imaging processor coupled to the direct conversion receiver and configured to provide image data associated with the scene based on the energy from the scattered illumination signal.