An UWB Physical Optics Approach for Fresnel-Zone RCS Measurements on a Complex Target at Non-Normal Incidence.

Area of Science:

• Electromagnetics and Applied Physics
• Radar Systems Engineering
• Computational Electromagnetics

Background:

• Accurate radar cross section (RCS) measurement is crucial for target characterization.
• Traditional far-field RCS measurements require large distances, posing practical challenges.
• Near-field measurement techniques often require complex data processing and calibration.

Purpose of the Study:

• To develop a fast and simple method for measuring RCS of complex targets.
• To enable accurate RCS measurements at non-normal incidences and Fresnel region distances.
• To provide a practical solution for RCS measurement in perturbed environments.

Main Methods:

• Combines physical optics approach with field distribution averaging over antenna apertures.
• Introduces a field-zone extrapolation factor derived from far-field and Fresnel region analytical expressions.
• Applies distance averaging, coupling subtraction, or time gating for multipath environments.

Main Results:

• The proposed method effectively corrects RCS measurements made at Fresnel region distances.
• Experimental validation shows reasonable agreement between measured and simulated RCS at non-normal incidence.
• The technique simplifies the measurement configuration to two horn antennas and a vector network analyzer.

Conclusions:

• The developed method offers a fast and accurate approach for RCS measurement in the Fresnel region.
• It provides a viable alternative to traditional far-field RCS measurements, especially for complex targets.
• The technique's robustness in multipath environments enhances its practical applicability.