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It is natural to approach multi-channel SAR in terms of spatial diversity concepts developed for multiple-input-multiple-output (MIMO) communications and recent advances in MIMO radar. We introduce the MIMO SAR concept in this paper, and the goal here is to research the concept and potential design of a new SAR application based on MIMO theory and techniques. MIMO technology which were develop originally...
Uniform amplitude arrays on a periodic lattice usually have to be thinned if a low sidelobe level is required. The choice of a thinning configuration has to be performed using an optimization algorithm. If the number of deactivated elements is not kept under control, good array configurations in terms of sidelobe level could result in large losses of directivity. In order to satisfy a constraint on...
Airborne radar has evolved from early systems where almost all radar characteristics were fixed to todaypsilas highly flexible, software-driven systems. The most recent advance has been the widespread adoption of active electronically scanned array (AESA) antennas, which has given the system designer unprecedented control of antenna characteristics. However, in common with most conventional radars,...
This paper describes the COSMO-SkyMed SAR instrument and its active phased array, developed by Thales Alenia Space Italia under contract of Italian Space Agency and Italian Ministry of Defence. Major focus is given to the description of the antenna, the architectural solutions and the technological results.
Through-the-wall radar imaging attempts to image complex scenes within enclosed structures. While most of the high-resolution imaging techniques assume point targets, indoor imaging requires dealing with single or multiple walls which are extended targets in nature and violate the point-target assumption. In order to provide high quality imaging, we need to consider point targets and extended targets...
Based on nonuniform L-shaped array, the paper presents a new time-space processing method for joint estimation of the frequency and 2D arrival angles of coherent signals over a wide frequency band, which is called wide-band time-space smoothing (WTSS) algorithm. The algorithm can precisely estimate 3D parameters of coherent signals with same digital frequency. Getting rid of the costly multidimensional...
The main idea that motivates this study is to improve the resolution of a radar mounted on an airplane, looking in the forward direction: this can be obtained by forming a synthetic array along the airplane line of flight. We term this new concept as ldquoForward-Looking Synthetic Aperture Radarrdquo (FLoSAR). We present a feasibility study that analyses the system geometry, evaluates the achievable...
To check the capabilities of a dasiashared aperturepsila, at FGAN the PALES experimental system is built up. Especially array signal processing with a multibeam system is investigated. In this paper the basics of signal detection by square law detectors are discussed. The proposed signal detection method is based on a time frequency representation. Besides signal detection also the PRF of the received...
Australia has been developing and fielding phased array applications since the early 1950s. The application areas range from radio astronomy and atmospheric sciences, through over-the-horizon radar, surface wave, microwave ship and airborne systems. Given Australia's unique geographical size, position, single continent and national identity, it is not surprising that much of this effort has been focussed...
This paper describes work carried out at QinetiQ to demonstrate real-time operation of space-time adaptive processing (RTSTAP) for airborne phased array radar, in a laboratory environment. RTSTAP processing is performed using field programmable gate array (FPGA) hardware and controlled via a MATLABcopy graphical user interface. The FPGA hardware is connected to the PACER (phased array concepts evaluation...
A new method for wideband spatio-temporal processing in the context of clutter mitigation and target detection is addressed in this paper. The frequency dependent, spatio-temporal steering vectors, are separated using a series expansion that depends on a sequence of Bessel function terms, and this is used to focus data vectors corresponding to various frequency components to a single frequency component...
It is commonplace to use an unweighted transmit aperture and a weighted receive aperture in radars utilising active electronically steered array (AESA) antennas. The preferred receive weightings are usually Gaussian or Taylor as these are perceived to give the best compromise between loss of main-beam directivity, minimised main-beam dilation and excellent sidelobe control. However, this is only part...
In the frequency modulated continuous wave radar systems, when the transmitter uses periodic linear symmetric triangular wave modulation, the received signal after processed by the mixer will have many harmonics. In the single target detection, this effect can be ignored. However, in the multi-target detection, targets with different ranges and velocities lead to overlapping of the harmonics. Using...
This paper presents measurement results on wave polarization for multi source scenarios. It focuses on the RF hardware requirements at the receiver to achieve low-cost and high-resolution estimation. The proposed system has duplicated RF receiver chains in order to simultaneously sample the double polarized antennas outputs. Low-cost and high accuracy within a large bandwidth are achieved by using...
This paper deals with miniaturization techniques and radiating optimization on UWB antenna in order to make an antenna array. The hard point with size reduction of an antenna is the back radiation, the cross polarization and the antenna adaptation. Several methods to keep the antenna adapted to our bandwidth [300 MHz - 3 GHz] are studied. A detailed study of the travelling wave elementary antenna...
Millimeter-wave band is the general trend for new communication, tracking radar and automotive systems. The crowd of RF frequency bands, the compactness of higher frequency radiating systems and the commercial availability of MMW components drive even more communications, tracking radars and automotive systems toward millimeter-wave band. Moreover, the antenna technology evolves from mechanical to...
The utilization of diversity in radar systems has shown improvements over conventional beamforming phased array radars in many aspects of the system performance including target detection probability, the number of identifiable targets, and beam-pattern synthesis. When linearly independent signals are transmitted, the signals received from targets at different locations are also linearly independent...
This paper describes an active electronically scanned array (AESA) FMCW radar with eight transceivers. Each transceiver has its own direct digital synthesizer (DDS) for signal generation which enables digital beam forming on transmit as well as on receive. The coherent operation of the eight transceivers and the capability to perform digital beam forming on transmit and receive is demonstrated. Also...
This paper discusses two adaptive spatial processing approaches that have been recently proposed for mitigating spread-Doppler clutter in skywave over-the-horizon (OTH) radar. The first is slow-time MIMO (SLO-MO) STAP which uses conventional waveforms that are phase-coded so as to be orthogonal after Doppler processing at the receiver, i.e. in ldquoslow-time.rdquo SLO-MO STAP is proposed as a means...
Coherent synthesis sparse aperture array radar can provide a long baseline with narrower beamwidth at the cost of grating lobes. In this paper, we propose a method to suppress grating lobes based on frequency MIMO technique. By transmitting M orthogonal waveforms with diverse frequencies from subaperture-to-subaperture, M beams can be formed with the same mainlobe direction. However, grating lobes...
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