An imaging radar seeker (8) for producing two-dimensional images of a target (2) is mounted on a missile (6) or other moving body, such as an automobile. A computer (40) directs the seeker (8) to operate sequentially in searching, tracking, and imaging modes. In the searching mode, a combination of circumferential rotation of antenna (12) of seeker (8) and frequency scanning of electromagnetic energy fed to antenna (12) enables seeker (8) to search for its target (2) over a conical field-of- view (16) or a wider, peripheral belt field-of-view (16). In the imaging mode, circumferential rotation of antenna (12) is stopped, and the tilt angle (A) of the linear array (32) of antenna (12) is stepped or continuously moved to compensate for radial movement of the radiated beam (14) caused by frequency stepping imparted by a frequency synthesizer (20) . This keeps the beam (14) fixed in space and centered on target (2). Inverse synthetic aperture imaging is used to create a two-dimensional image (4) of target (2) wherein the first dimension (range) is obtained by performing inverse Fourier transforms on the echo signals, and the second orthogonal dimension (cross-range or doppler frequency) is obtained by performing Fourier transforms. Array (32) can be a linear array of E-plane stacked linear waveguide antenna elements (38) operating in either the traveling wave mode or the standing wave mode.
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