Range, velocity, and geometric shape are primary features of a moving target. Obtaining these features usually needs high‐cost system and complicated signal processing. Here, a single‐frequency mechanism to detect these features simultaneously with digital programmable metasurface (DPM) in transmission type is proposed. For range‐velocity detection, the DPM can produce sum beams whose radiation phases are modulated by sequentially changing aperture codes of the metasurface to generate biphase coded signals, in which the Range‐Doppler algorithm is used to estimate the range and velocity information of a moving target. Then difference beams are generated by the metasurface, and the sum‐difference ratios of echo signals are used to locate the target. For two‐dimensional imaging, random radiation patterns are produced by the DPM, and the matched filtering algorithm is used to image the target. Since the proposed mechanism implements all detections based on a single programmable metasurface, the complexity and cost of detection systems are greatly reduced, showing promising potentials of DPMs in intelligent and universal electromagnetic sensing.

A Single Metasurface Can Perform Range‐Velocity Detection and Target Imaging Simultaneously at Single Frequency

In this article we consider a problem of reliable modeling of echo signals and angle noise of distributed objects using twodimensional geometric models with random statistically unrelated signals. The conditions that ensure the invariance of distribution parameters of the angle noise generated by an arbitrary N-point configuration of a two-dimensional geometric model are obtained. In the particular case of a model whose emitters are supplied with signals of equal power, the conditions of invariance are reduced to the location of the model points on the plane in the form of a regular polygon. These results can be used to synthesize mathematical models used for simulating reflections from distributed objects and for developing a hardware-software complex for the simulation of electromagnetic fields reflected from the Earth surface, atmospheric inhomogeneities, the sea surface, etc.

https://vre.instel.ru/jour/article/download/828/818

Об инвариантности параметров распределения углового шума произвольной n-точечной геометрической модели к углу визирования

Angle glint can is the distortion in the radar echo signal phase front and is observed as deviation of the direction of power flow from the radial direction and give rise to radar pointing errors. The mechanism that gives rise to these errors is also responsible for angular errors observed in radar multipath conditions. The effect can be either natural or intentional and is due to the destructive interference between the reflections from different scattering centers on the target. The apparent direction from where a scattered field originates is perpendicular to the phase front of the wave, and in regions where there is destructive interference between the fields there can be significant distortion of the front. For various glint angles using different frequencies the received echo power is calculated and the result is simulated using MATLAB. The range glint is also calculated using different carrier frequency. In obtaining the received echo power, the polarization aspect is considered and the received echo power for different glint angle is simulated for different polarization. Thus the different simulation has been carried out to find the glint error for different scatterers. The radar will move in such a direction so as to nullify the glint angle error produced by the scattering surface of the target.

S. Rajalakshmi

Papers

Estimation of angle glint for different radar targets

Estimation of angle glint for different radar targets