SAR Experiments Using a Conformal Antenna Array Radar Demonstrator (original) (raw)
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Antenna Design and Beamforming for a Conformal Antenna Array Demonstrator
2006 IEEE Aerospace Conference, 2000
The present paper 1,2 gives an overview over a radar demonstrator currently under development and the design of the system's conformal antenna array front-end. Important system parameters and overall performance of the planned system are described and experimental results for reflection coefficients, mutual coupling and embedded antenna element far field patterns will be included as well as simulated pattern synthesis results for different operational modes. In addition, a circularly polarized antenna sub-array suitable for integration in double curved apertures has been developed. The structure combines multiple cavity-backed patch antennas on a circular substrate and is connected to the feed network via a single coaxial line. A conformal antenna array of spherical shape based on this technology is currently being built for beam forming experiments.
PAMIR – a wideband phased array SAR∕MTI system
IEE Proceedings - Radar, Sonar and Navigation, 2003
Air-and spacebome imaging radar systems in forthcoming surveillance and reconnaissance tasks have to meet increasingly severe demands. The next generation of top-level synthetic aperture radar (SAR) systems will comprise, among others, high resolution and longrange imaging capabilities, highly sensitive ground moving target indication and a multitude of sophisticated operational modes. The variety of tasks can be fulfilled only by the use of a reconfigurable phased array antenna together with a comprehensive wideband system design and a multichannel capability. At FGAN a new experimental X-band radar has been conceived, which will possess in its final upgrade an electronically steerable phased array consisting of 16 autonomous and reconfigurable subapertures, five independent receive channels, and a total signal bandwidth of about 1.8 GHz. The sensor is called PAMIR (Phased Array Multifunctional Imaging Radar). It is envisaged to demonstrate SAR imaging at a very high resolution and for a long range. The fine resolution will also be achieved with inverse SAR (ISAR) imaging of ground moving objects. Furthermore, the number of receive channels will allow ground-moving target indication (GMTI) by space-time adaptive processing and single-pass interferometric SAR (IRAR) with a very high 3-D resolution. In its current stage of extension PAMIR is operable with one receive channel and a mechanically steerable antenna array. The system design and the intended capabilities of PAMIR are described. Ground-based and airborne experimental results concerning high-resolution SAR and ISAR imaging are also presented.
Beamspace Space-Time Adaptive Processing for Conformal Array Radars
2006 IEEE Conference on Radar, 2006
This paper presents a beamspace space-time adaptive processing (STAP) approach to conformal array radar applications. The spatial channels in beamspace STAP are designed to have the same phase center, but different beam orientations and/or shapes. The joint-domain localized (JDL) algorithm and Σ∆-STAP (employing sum and difference beams) are two special cases of beamspace-STAP. This paper develops a theory for a generalized beamspace STAP and applies it to conformal arrays. The desired beam pattern characteristics for beamspace STAP are identified with supportive examples. In practice, the beam pattern sidelobe structure is not controllable because of near-field effects, mutual coupling, and various other errors. A practically feasible design that employs a low sidelobe mainbeam combined with a few non-tapered beams (sum and/or difference beams) is developed in this paper. An iterative method is used to synthesize the desired conformal array patterns for beamspace-STAP. Several beamspace-STAP examples for a cylindrical array and a domeshaped array, as representatives of conformal arrays, perform very well and the results are consistent with the theory.
Advanced spaceborne SAR systems with array-fed reflector antennas
2015 IEEE Radar Conference (RadarCon), 2015
Since its invention 60 years ago the synthetic aperture radar (SAR) principle has been continuously pushed further in terms of information density. Future SAR systems are required to collect data in different frequency bands and polarizations with finer spatio-temporal resolution and higher quality. These requirements drive technology developments with a trend towards digital radars. This type of radar is highly flexible and configurable compared to its analogous counterpart and allows a relatively easy implementation of digital beamforming (DBF) as well as multiple input multiple output (MIMO) techniques. The demand of highly sensitive SAR sensors enforces antenna concepts with large aperture. A promising candidate are large deployable mesh reflector antennas fed by an array of feed elements. Each feed element, or a subset of feed elements, defines a digital channel to be further processed on board the spacecraft or on ground. These innovative class of high-information content SAR sensors are the result of a carefully optimized design in both, the hardware and the signal processing domain. Here, an advanced SAR sensor concept based on array-fed reflector antennas shall be presented. Space, time and frequency adaptive beamforming techniques which complement the antenna design are introduced and demonstrated by means of numerical simulations.
Research Square (Research Square), 2022
One of the most demanding requirement of RADAR system is estimation of Direction of arrival (DoA) estimation when two or more objects are very close to each other. It is quite difficult for any ranging and detection system to distinguish between them. Multiple antenna receiver technologies such as array antenna technology have advanced to the point, where they can achieve high angular resolution. Multiple antenna arrays are Planar array and Conformal array.Radiating elements are equally spread over surfaces in planar(URA) and conformal antennas apertures are of curved surface. Main problem with planar arrays is scan angles, are about +/-60 • from broadside.In conformal array, scan angle is about 360 • .This extended scan is very much useful for missiles and high speed air crafts radar, compare to planar array. So this paper checks how conformal array is better for high speed air craft's radar system for achieving improved angular resolution. To achieve higher resolution in DoA estimation, subspace-based algorithms Multiple Signal Classification (MUSIC) is used with conformal array. This work focuses on comparing Conformal arrays and Uniform Rectangular arrays for DoA estimation. This paper examines the effect of using the MUSIC algorithm along with two different kinds of receivers to check for noise level and improved DoA resolution. Conformal array receivers shows two closely spaced objects are resolvable with 25 perecent improvement in azimuth angle and 68 perecent in elevation angle over the Uniform Rectangular Array(URA).As the number of array elements increased in conformal array,more accuracy in DOA estimation with reduced grating lobes achieved.The performance of these systems is assessed using computer simulation studies using Matlab. The findings shows conformal multi-array receiver outperforms URA receiver.
Performance analysis of high gain beamforming conformal array for avionic applications
International Journal of Systems, Control and Communications, 2018
In modern wireless avionic systems like aircraft, radar, missile and satellite communication, demand wideband or multiband antennas to improves the data rate transmission. In this paper, two slotted patches are asymmetrically assembled on a cylindrical thick foam substrate to obtain high gain, wide bandwidth and wide angular coverage for avionic applications. The reported antenna is operating in 3.8 GHz band with a bandwidth of 421 MHz, E-plane-3 dB HPBW of 150° and H-plane HPBW of 62°. The measured realised gain of the antenna is above 6 dBi throughout the operational band. The prototype of the proposed configuration is fabricated and showing good agreement with simulated results.
Conformal phased array with beam forming for airborne satellite communication
2008 International ITG Workshop on Smart Antennas, 2008
For enhanced communication on board of aircraft novel antenna systems with broadband satellite-based capabilities are required. The installation of such systems on board of aircraft requires the development of a very low-profile aircraft antenna, which can point to satellites anywhere in the upper hemisphere. To this end, phased array antennas which are conformal to the aircraft fuselage are attractive. In this paper two key aspects of conformal phased array antenna arrays are addressed: the development of a broadband Ku-band antenna and the beam synthesis for conformal array antennas. The antenna elements of the conformal array are stacked patch antennas with dual linear polarization which have sufficient bandwidth. For beam forming synthesis a method based on a truncated Singular Value Decomposition is proposed.
IET Radar, Sonar & Navigation, 2017
The synthetic aperture radar (SAR) system equipped on the hypersonic platform in the near space presents many advantages compared with the conventional airborne SAR. However, due to the complex aerodynamic configuration and flight characteristics of the hypersonic platform, the radar design is facing some new challenges. Taking into account the new features of the platform, in this study the authors analyse the conformal design requirements of the array antenna, as well as the prominent contradiction between the high resolution and wide swath of SAR. After establishing the model of the conformal array antenna and the space coordinate system of the far-field radiation, a specific process of synthesising the antenna pattern is given. Furthermore, the antenna mask templates of optimising the antenna pattern are generated based on the main performance measures of the SAR system, and the modified meta particle swarm optimisation algorithm is exploited to obtain the optimal excitation phase of each array element in synthesising the ultimate antenna pattern. Finally, simulation results verify the effectiveness of the method, where the performance of the optimised antenna pattern is evaluated numerically.
Antenna technology requirements for next-generation spaceborne SAR systems
Antennas and Propagation Society International Symposium, 1983
A measurement technique i s i n use which permits the rapid measurement o f d i e l e c t r i c p r o p e r t i e s of material over the frequency readily adaptable to continuous on-line process control, dielectric range o f 100 MHz t o 18 GHz. This non-destructive measurement i s thickness measurement, and low and high temperature measurements.