| 1. |
- Aldhubaib, Faisal, et al.
(författare)
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A Radar Target Signature based on Resonance and dual Polarization Features
- 2008
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Ingår i: 2008 Asia Pacific Microwave Conference, APMC 2008; Hong Kong; China; 16 December 2008 through 20 December 2008. - 9781424426423 ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- A physically based radar target scattering signature is derived from observable data using a frequency domain scattering model that incorporates the backscattered radar target polarization response at the target natural resonance frequencies (NRF). Two rotationally symmetric targets of simple but similar characteristic geometry are used to demonstrate the theoretical feasibility and the ability to distinguish the two similar targets by this proposed signature.
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| 2. |
- Aldhubaib, F., et al.
(författare)
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Aspect segmentation and feature selection of radar targets based on average probability of error
- 2010
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Ingår i: IET Microwaves, Antennas and Propagation. - : Institution of Engineering and Technology (IET). - 1751-8725 .- 1751-8733. ; 4:10, s. 1654-1664
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Tidskriftsartikel (refereegranskat)abstract
- Through statistical estimation by a non-parametric model, a fused polarimetric and resonant return from the radar target is modelled as a function of the target aspect angle. The outcome of this type of modelling is a set of non-parametric density estimates, which are then used to represent this target in a multi-dimensional probability space. These densities within this probability space can be well separated and therefore utilised to make decision rules to identify targets of interest. The return set to be modelled is the average power set associated with spectral bands centred on the target natural resonant frequencies. This return set is mapped into density set using a Gaussian kernel function; subsequently, the density set will be considered as the target radar feature set of interest. To decrease density overlapping between respective densities of different targets, a criterion based on the Bayesian error is employed; first, to bisect the aspect global range into smaller sectors, and second, to select discriminative features that can minimise the average probability of error between the targets respective features. The results show that two targets with similar resonant frequencies can be separated by the Bayesian error criterion based on the proposed features. A simple likelihood ratio test had more than 80% success down to 20 dB of signal-to-noise ratio.
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| 3. |
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| 4. |
- Dobsicek Trefna, Hana, 1979, et al.
(författare)
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Evolution of an UWB antenna for hyperthermia array applicator
- 2012
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Ingår i: Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012. Prague, 26-30 March 2012.. - 9781457709180 ; , s. 1046 - 1048
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Konferensbidrag (refereegranskat)abstract
- Designs of three UWB antennas and their suitability to be used as a basis antenna element in the hyperthermia applicator for the treatment of tumors in head and neck region are considered. The antennas with reflection coefficient less than -10 dB at frequency range 350 MHz to 1 GHz are immersed in water bolus. The evaluation of the SAR distributions was carried out by comparing the different cross-sections of muscle equivalent phantom. Numerical simulations were performed in CST Microwave studio and verified experimentally via measurements of S-parameters and SAR distributions in phantoms.
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| 5. |
- Fayazi, Seyedeh Shaghayegh, et al.
(författare)
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Microwave imaging of near-field object using ultra-wideband synthetic aperture radar algorithm
- 2012
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Ingår i: 2012 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM (APSURSI). - 1522-3965. - 9781467304627
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Konferensbidrag (refereegranskat)abstract
- A simple procedure that suppresses artefact from ultra-wideband (UWB) synthetic aperture radar (SAR) images is proposed and verified using experimental data. The proposed imaging solution is useful for imaging small objects located in the near-field region with less ambiguity.
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| 6. |
- Fayazi, Seyedeh Shaghayegh, et al.
(författare)
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UWB SAR Imaging of Near-Field Object for Industrial Process Applications
- 2013
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Ingår i: 7th European Conference on Antennas and Propagation, EuCAP 2013, Gothenburg, Sweden, 8-12 April 2013. - 2164-3342. - 9781467321877 ; , s. 2245-2248
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Konferensbidrag (refereegranskat)abstract
- Ultra wideband technology becomes more widely used for near-field object detection. We present an aperture synthetic radar (SAR) system using ultra-wideband (UWB) signals for such applications. One of the problems with UWB time-domain SAR imaging algorithm is the artefact originated from scattered field of adjacent objects. In this paper an algorithm based on the Range Point Migration (RPM) method is used to alleviate this problem. This method estimates a possibility distribution of the optimal Direction of Arrival (DOA) of the scattered field from objects. A weighting factor based on this possibility is used to suppress the effect of artifact scattered fields. The results in the paper show that the UWB SAR accompanied with RPM can produce an image of an object with a significant suppression of undesired artifact from scattered field of adjacent objects.
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| 7. |
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| 8. |
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| 9. |
- Johansson, Markus, 1978, et al.
(författare)
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Comparison between Two Phase Retrieval Methods for Electromagnetic Source Modeling
- 2011
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Ingår i: Progress in Electromagnetics Research B. - 1937-6472. ; 30, s. 239-253
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Tidskriftsartikel (refereegranskat)abstract
- Phase-retrieval from measured phaseless field data is of interest for various applications including electromagnetic dosimetry, electromagnetic compatibility investigations, near-field to far-field transformations and antenna diagnostics. In this study two phaseretrieval methods are compared. The first method, the adjoint field method, employs a gradient-based optimization algorithm based on the adjoint fields. The second method, the phase angle gradient method, uses an optimization algorithm based on the phase angle gradients of a functional. The methods are tested with numerical test cases and the phase angle gradient method is found to retrieve the phase with the best accuracy. Moreover it gives results that agree well with correct phase.
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| 10. |
- Johansson, Markus, 1978, et al.
(författare)
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Electromagnetic Source Modeling using Phase Retrieval Methods
- 2011
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Ingår i: 30th URSI General Assembly and Scientific Symposium, URSIGASS 2011, Istanbul, 13-20 August 2011. - 9781424451173 ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- Modeling of the field distributions from electromagnetic sources is of interest for various applications for example electromagnetic compatibility investigations, near-field to far-field transformations, antenna diagnostics and electromagnetic dosimetry. In order to determine whether exposure safety guidelines, such as the EU directive 2004/40/EC, are complied with, source modeling methods are important. Two methods for determining the total field, including phase information, when only field amplitudes have been measured on a set of planes in front of an electromagnetic source have been developed. The first method, the adjoint field method, is a gradient based optimization algorithm based on the adjoint fields. The second method, the phase angle gradient method, employs an optimization algorithm based on the phase angle gradients of a functional. Promising results have been obtained both for numerical test cases and for measured field.
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