Wavefront distortion analysis of a microwave collimator system with complex horn feed

• Main Authors: V. V. Neyolov, E. L. Kapylov, A. A. Samorodov, B. A. Samorodov
• Format: Article
• Language: English
• Published: CRI «Electronics» 2019-12-01
• Series: Радиопромышленность
• Subjects: collimator; irradiators assembly; defocusing; curvature of the probe field wavefront
• Online Access: https://www.radioprom.org/jour/article/view/628
• ISSN: 2413-9599; 2541-870X

Phase structure distortion of the probe field that occurs when the collimator-type assemblies of irradiators used in measuring the polarization scattering matrices of location objects are used as part of the radar measuring complex was discussed. It is shown that, due to the specific design, the phase centers of the irradiators in the assembly are removed from the collimator focus, resulting in the appearance of longitudinal-transverse defocusing, which is expressed in the slope and curvature of the wavefront of the probe field. For a quantitative analysis of these distortions, a method for calculating the ray path in the «irradiator – collimator mirror – test zone» system is proposed. For the MAK-5 collimator, numerical estimates of the phase distribution and slope of the wavefront of the probe field, as well as variations in bistatic angles corresponding to the use of an irradiator assembly for radar measurements, were obtained. It is shown that, with the displacements of the phase centers of the irradiators in the assembly not exceeding the wavelength, the field formed by them has a quasi-plane character – the phase change in the plane perpendicular to the propagation direction does not exceed 8°. However, the slope of the wavefront of the probe field to the longitudinal axis of the collimator, as well as the fundamentally bistatic nature of the measurements, are sources of inextricable systematic errors in measuring the scattering characteristics of targets when using irradiator assemblies.