For sonar imaging platforms with limited space, small-size arrays pose a challenge to high-resolution imaging application. To address this problem, by using bandwidth synthesis, a high-resolution imaging method is pro...
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ISBN:
(纸本)9781728154466
For sonar imaging platforms with limited space, small-size arrays pose a challenge to high-resolution imaging application. To address this problem, by using bandwidth synthesis, a high-resolution imaging method is proposed specially for small-aperture array in this paper. As wideband signals, especially ultra-wideband (UWB) signals are potentially capable of high-resolution with few elements, the proposed method is based on large-bandwidth signals. First, to overcome the limitation on instantaneous system bandwidth, large-bandwidth signals are obtained from a set of stepped-frequency chirp pluses with small-bandwidth. Second, paired-element-based imaging approach is proposed by using synthesized large-bandwidth signals. All pairs of array element signals are dechirped for pulse compression, and then delayed and summed for high-resolution image formation. Numerical simulations are carried out to test the performance of the proposed method. Simulation results show that the proposed method is capable of high-resolution image formation with small-aperture array.
Based on Taylor series expansion and strain components expressions of elastic mechanics, we derive formulae of strain and rotation tensor for small arrays in spherical coordinates system. By linearization process of t...
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Based on Taylor series expansion and strain components expressions of elastic mechanics, we derive formulae of strain and rotation tensor for small arrays in spherical coordinates system. By linearization process of the formulae, we also derive expressions of strain components and Euler vector uncertainties respectively for subnets using the law of error propagation. Taking GPS velocity field in Sichuan-Yunnan area as an example, we compute dilation rate and maximum shear strain rate field using the above procedure, and their characteristics are preliminarily car- ried on. Limits of the strain model for small array are also discussed. We make detailed explanations on small array method and the choice of small arrays. How to set weights of GPS observations are further discussed. Moreover relationship between strain and radius of GPS subnets is also analyzed.
This paper details the procedure for synthesis of arbitrary patterns from an irregular antenna array with few elements. The procedure involves determining the embedded radiation pattern for each antenna element and th...
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ISBN:
(纸本)9780996007870
This paper details the procedure for synthesis of arbitrary patterns from an irregular antenna array with few elements. The procedure involves determining the embedded radiation pattern for each antenna element and the mutual coupling matrix for calculating the active reflection coefficients. Patterns are synthesized through a least-squares method. The procedure is demonstrated with an array of UHF antennas to form linearly and circularly polarized radiation patterns.
It is a trend to replace the traditional discrete antenna with the array plane antenna, and the new electromagnetic interference problem produced by the array plane antenna is also the focus of the current research. T...
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ISBN:
(纸本)9781509047437
It is a trend to replace the traditional discrete antenna with the array plane antenna, and the new electromagnetic interference problem produced by the array plane antenna is also the focus of the current research. This paper uses both simulation and experiments to research the issue about suppression of electromagnetic interference under the condition of two array plane antenna be laid in same plane. By means of simulation, the inhibitory effect of electromagnetic coupling between two array planes and the radiation characteristics of array plane antenna are studied on condition of concave/non-concave layout. In the laboratory environment, the inhibitory effect of electromagnetic coupling between two array planes on condition of concave/non-concave layout is studied by using the small array plane. The results show that the radiation characteristics of the antenna can not be affected by the concave layout array plane antenna, and the isolation between two array planes can be promoted by 5 dB.
With the development of semiconductor technology, microwave technology, computer technology and considering the complex electromagnetic environment during RF operation of the phased array radar system, the microwave s...
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It is a trend to replace the traditional discrete antenna with the array plane antenna, and the new electromagnetic interference problem produced by the array plane antenna is also the focus of the current research. T...
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ISBN:
(纸本)9781509047444
It is a trend to replace the traditional discrete antenna with the array plane antenna, and the new electromagnetic interference problem produced by the array plane antenna is also the focus of the current research. This paper uses both simulation and experiments to research the issue about suppression of electromagnetic interference under the condition of two array plane antenna be laid in same plane. By means of simulation, the inhibitory effect of electromagnetic coupling between two array planes and the radiation characteristics of array plane antenna are studied on condition of concave/non-concave layout. In the laboratory environment, the inhibitory effect of electromagnetic coupling between two array planes on condition of concave/non-concave layout is studied by using the small array plane. The results show that the radiation characteristics of the antenna can not be affected by the concave layout array plane antenna, and the isolation between two array planes can be promoted by 5 dB.
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