Scalar Calibration for Broadband Phaseless Antenna Measurements Based on Indirect Off-Axis Holography

A scalar calibration method for broadband off-axis holography phaseless antenna characterization and diagnostics is presented in this communication. With the proposed method, the need of vector calibration, inherent to off-axis holography setups, is bypassed by means of an intermediate step in which a well-known antenna, whose phase can be analytically modeled, is used to retrieve the phase of the reference antenna by applying the off-axis holography method twice. The method is especially suited for near-field characterization of high-gain millimeter- and submillimeter-wave antennas in which phase acquisition is a difficult task, requiring complex and expensive instrumentation and steady conditions. The phase of the field is retrieved at each point of the acquisition surface for a set of frequencies, and, consequently, the technique can be applied independently of the acquisition geometry. Validation examples are presented in the W-band.