Numerical four phase shifting microwave holography with phase step error analysis

Microwave holography utilizes an antenna to record the hologram. In a phase shifting microwave holographic method, the antenna has to perform the 2D scanning over an area corresponding to each phase shift in reference wave. Since this methodology requires phase shifting in each scan, this makes the process lengthy and laborious. In this work, a numerical 4-step phase shifting method is presented for generating the microwave hologram, in which a single (0 degrees phase) hologram is recorded experimentally and the other three holograms are generated numerically by shifting the phase in reference wave. The amplitude and phase information of object is extracted using angular spectrum diffraction method. An error introduced by various components in experiments is calculated and corrected to enhance the accuracy of reconstructed phase values. The calculated phase step error for the experiment is 0.0501 rad. The quantitative and qualitative results along with the experimental phase shifting phase results are shown to envision the applications of numerical phase shifting microwave holography in imaging of metallic objects and highly scattered biological phantom.