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Different recent approaches have demonstrated the feasibility of applying millimetre-waves (MMW) for the imaging of objects at a person's body. The utilisation of MMW allows for the detection of both metallic and non-metallic objects. In order to reduce costs a low number of transmit-receive modules should be used. Furthermore, the person should also be illuminated from different angles in order to avoid shadowing effects as good as possible. A way to fulfil these two conditions is to place one sensor above and another one below the person and either rotate the person standing on a turntable (inverse synthetic aperture radar, ISAR) or move the sensors on a circular path around the person (synthetic aperture radar, SAR). The goal of the reconstruction is to obtain information about the shape of possible threats and their positions in all three dimensions. During processing as a first step, the reconstruction is done along range and azimuth, which span the principal surface given by the suggested sensor configuration. Afterwards, the third spatial dimension can be determined by combined evaluation of the resolution capabilities of the curved synthetic aperture and the interferometric phase of two coherent receiving channels of one sensor. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of non-cooperative target recognition. Specifically, the aim is the automatic recognition of ship targets from inverse synthetic aperture radar (ISAR) images. For this purpose a new two-step multi-feature based technique is proposed; this technique uses a number of features extracted from the ship radar image and matches these features with those extracted from the images obtained by properly projecting the target models of the classification library. Both cases of a priori known or unknown ship aspect angles are considered: the knowledge of the ship aspect (as available from tracking data) allows the selection of the candidate models on the basis of the matching between the ship and the model length, thus resulting in a performance improvement. Moreover, both single- and multi-frame-based processing techniques are proposed in order to assess the performance improvement achievable when an increasing number of ISAR images are involved in the decision; the fusion strategy adopted for the exploitation of the information from the multiple images is also described. The performance of the overall proposed technique is deeply investigated against simulated data. Results of its application to a set of live ISAR images of a ship target are also provided showing the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Progress in the study of space-surface synthetic aperture radar is presented. Global navigation satellite system is considered as the transmitter of opportunity. It highlights the various important issues to successfully obtain an image. The experimental testing of the imaging algorithm is presented and verified using a GLONASS satellite signal. [ABSTRACT FROM AUTHOR]

Target rotation is the desired motion to obtain descriptive inverse synthetic aperture radar images. However, it can generate blurring effects: the migration through resolution cells. This blurring is more severe when the rotation rate is non-uniform. A method to estimate the non-uniform rotation rate (second-order model) for non-cooperative targets is addressed here. The technique considers the possibility of existence of slant range migration induced by angular motion, unlike other approaches. It needs a previous estimation of the range and radial velocity of two prominent points at two instants and minimises a function in order to estimate the motion parameters, which are used to polar format the radar data. The method is compared with the moving target imaging algorithm of Werness et al. and a time – frequency based technique. Simulated data are used to verify the approach and make the comparisons. [ABSTRACT FROM AUTHOR]

Based on compressed sensing, an inverse synthetic aperture radar (ISAR) enhancement technology is proposed. The ISAR enhanced imaging system is constructed, and then utilising the sparsity of multi-radar signals, the optimum function for point enhancement and edge enhancement is established. Compared with spectral estimation methods, the new processing provides a higher quality ISAR image without the number estimation of scattering centres. Simulation results demonstrate the validity of the proposed processing. [ABSTRACT FROM AUTHOR]

The proposed quasi-analytical method undertakes the shaping of a desired footprint as a composition of several Ø-symmetric circular Taylor patterns exhibiting flat-topped beams. The final pattern is obtained after sampling the obtained circular aperture for circular grid planar arrays. A square and a rectangular footprint pattern, both radiated by a planar array with 1246 elements, demonstrate the performance of the technique. [ABSTRACT FROM AUTHOR]