The radar cross-section (RCS) measurements for cylinders with different surface roughness have performed in the terahertz bands. The terahertz radar system has 220 and 440 GHz carrier frequencies. It is a solid-state system whose base band signal is generated by a phasor network analyser. The original recorded data are calibrated by the results of the smooth surface cylinder. These calibrated RCS results are compared with calculated results. The experiments suggested that targets with the rough surface will provide complicated scattering in terahertz. The results of this experiment can prove that the surface roughness of the target has a certain impact on RCS measurement results in the terahertz band.

One of the major concerns in radar cross-section (RCS) measurements is the isolation of the target echo from unwanted spurious signals. Generally, the method of software range gate is applied to extract useful data. However, this method may not work to expectations, especially for targets with a large length-width ratio. This is because the effective target zone is dependent on the aspect angle. The implementation of conventional fixed range gates will introduce an uneven clutter signal that leads to a decline in signal-to-noise ratio. The influence of this uneven clutter signal becomes increasingly severe in the terahertz band, where the wavelength is short and the illumination power is weak. In this work, the concept of adaptive range gates was adopted to extract a target echo of higher accuracy. The dimension of the range gate was determined by the angle-dependent radial projection of the target. In order to evaluate the performance of the proposed method, both experimental measurements and numerical simulations were conducted. Noticeable improvements in the signal-to-noise ratio at certain angles were observed.

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In the terahertz band, the dispersive characteristic of dielectric material is one of the major problems in the scaled radar cross section (RCS) measurement, which is inconsistent with the electrodynamics similitude deducted according to the Maxwell’s equations. Based on the high-frequency estimation method of physical optics (PO), a scaled RCS measurement method for lossy objects is proposed through dynamically matching the reflection coefficients according to the distribution of the object’s facets. Simulations on the model of SLICY were conducted, the inversed RCS of the lossy prototype was obtained using the proposed method. Via comparing the inversed RCS with the calculated results, the validity of the proposed method is demonstrated. The proposed method provides an effective solution to the scaled RCS measurement for lossy objects in the THz band.