Abstract: A microwave and millimeter wave imaging system. In either a far-field or a near-field detection mode, a radially-polarized probe transmits an imaging signal along a predetermined scan path to detect a target in a sample. The imaging signal's orientation is independent of the target's orientation and changes at each target as the probe transmits the signal during scanning. A measurement system receives scattered waves reflected from the sample via a single channel and images the sample and the target based on the reflected waves independent of the orientation of the target.