Phenomenology of Doppler forward scatter radar for surface targets observation

Forward Scatter Radar for Air Surveillance: Characterizing the Target-Receiver Transition from Far-Field to Near-Field Regions

“…In other words, the Fraunhofer approximation gives a field radiated by a target that can be derived from elementary surfaces radiating in a parallel fashion; as a result, the interference phenomenon does not generate a shadow region. Such observations are in full agreement with the results in [17], where it is shown that a model for the FSR in the far-field region can be obtained by modulating the signal re-irradiated by the target in the far zone with the Doppler signature produced by a moving point-like scatterer.…”

“…It is also noted that, in the frame of civil applications, the possibility to apply FSR systems as passive radar configurations with no power emission may result in being particularly effective [9][10][11][12][13][14][15]. Different types of FSRs, both wide-band and narrow-band, have been analyzed so far, and simple models assuming far-field (FF) conditions have recently been proposed [16][17][18]. Nevertheless, a wider diffusion of the FSR technique especially for short-range applications would largely benefit from the availability of a comprehensive EM model of the involved scattering phenomenon, also valid in near-field (NF) conditions.…”

“…Nevertheless, a wider diffusion of the FSR technique especially for short-range applications would largely benefit from the availability of a comprehensive EM model of the involved scattering phenomenon, also valid in near-field (NF) conditions. In this frame, a straightforward approach has been proposed in [17] and used in [19][20][21][22], where the received signal is decomposed into a chirp-like waveform, which is the Doppler signature related to the motion, and an envelope pattern, which is in turn a function of the target shape and size. In any case, a fundamental assumption involving FF conditions has been considered so far to evaluate the signal collected by the receiver: this requires that the distance between the transmitting (Tx) antenna and the target, as well as the distance between the target and the receiving (Rx) antenna are sufficiently large in terms of the involved wavelengths.…”

Simultaneous data collection of small maritime targets using multistatic radar and forward scatter radar

“…The FSR system is a multi-frequency continuous wave (CW) radar developed at the University of Birmingham and is used as part of an ongoing investigation into both target and clutter signatures in the maritime environment [5][6][7][8]. It consists of a single multi-frequency transmit node and a corresponding receive node.…”

“…It is very interesting to note that for many of the examples shown, the situation with no sphere target being towed produced higher SCR values in the two bistatic nodes (Nodes 1 and 2), whereas for the monostatic Node 3, this was only found to be true on one occasion. The formation is fundamentally due to the sweeping of the target forward scatter lobe pattern across the receive antenna [6]. In essence the target acts like a reradiating antenna creating a highly directive FSCS pattern dictated by the silhouette shape of the target itself, where the main lobe width and maximal FSCS are given by,…”