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1. chinaXiv:201703.00250 [pdf]

A Novel Single-Layer Unit Structure for Broadband Reflectarray Antenna

Chunhui Han; Yunhua Zhang; Qingshan Yang
Subjects: Geosciences >> Space Physics

A novel X-band single-layer unit cell structure with enhanced bandwidth for linearly polarized microstrip reflectarray antenna is proposed. The unit-cell structure is composed of two circular rings, each with a pair of gaps which are orthogonally placed, and two identical phase-delay lines attached to the outer circular ring. With this novel structure, a linear phase response ranging about 550° is achieved by varying the length of the phase delay line. An offset-fed reflectarray antenna composed of 277 elements forming an octagon-shape aperture is designed, fabricated, and measured to verify the broadband characteristic of the proposed unit cell. Measurement results show that 20% 1-dB gain bandwidth is realized. Besides, the maximum gain at 10 GHz is about 26.38 dBi, which means about 51.3 % efficiency is achieved. At the same time, the side lobe level and cross polarization for E-plane are also measured which are below ?17.5 dB and ?26 dB, respectively.

submitted time 2017-03-10 Hits464Downloads296 Comment 0

2. chinaXiv:201701.00030 [pdf]

Characterization of Mixed Target Scattering Using Random Similarity

Dong, Li; Yunhua, Zhang; Yueying, Tang
Subjects: Geosciences >> Space Physics

A random similarity parameter is proposed which can measure not only the scattering similarity of any two scatterers but also the scattering randomness. The parameter covers both the similarity parameters developed by Yang et al. and Chen et al., and provides a fast and competent alternative to the scattering entropy H parameter. The excellence of the parameter on target discrimination is demonstrated by simply applying it to the terrain classification.

submitted time 2017-01-04 Hits970Downloads413 Comment 0

3. chinaXiv:201701.00029 [pdf]

Unified Phenomenological Decomposition of Radar Targets

Dong, Li; Yunhua, Zhang
Subjects: Geosciences >> Space Physics

Huynen phenomenological decomposition as the first for-malized target decomposition has not been widely accepted. Huynen’s preference for scattering symmetry and regularity restricts not only the application of this decomposition but also its unification with other target dichotomies such as the Barnes-Holm decomposition and Yang decomposition. The non-uniqueness issue then arises because we may have dif-ferent dichotomies of radar targets, but we have no idea on how to select them. Recently, a unified Huynen dichotomy was developed by Li and Zhang to extend Huynen decom-position for a full preference for symmetry and regularity, non-symmetry, irregularity, as well as their couplings. The dichotomy covers all the existing dichotomies and provides an excellent discrimination of radar targets. This paper gives a concise review of the Huynen-type target dichotomies to investigate the existing concerns influencing the application of such decompositions and the corresponding coping me-thods. We hope this review will help to promote the wide acceptation of Huynen-type target dichotomies in the future.

submitted time 2017-01-04 Hits756Downloads358 Comment 0

4. chinaXiv:201701.00020 [pdf]

Scattering preference pyramid classification of PolSAR data based on canonical huynen dichotomy

Dong, Li; Yunhua, Zhang
Subjects: Geosciences >> Space Physics

Huynen decomposition prefers the world of basic symmetry and regularity (SR) in which we live. However, it is just this preference prevents Huynen decomposition from analyzing the non-symmetric (NS) and irregular (IR) targets. The canonical Huynen dichotomy is proposed to provide two competent supplements to Huynen decomposition by developing two other target dichotomies with the scattering preferences for IR and NS. In virtue of an adaptive combination and permutation of the scattering preferences of the canonical dichotomy, a scattering preference pyramid description of the mixed scattering is developed in this paper. The pyramid is composed of three layers to reflect three different degrees of scattering randomness. Each layer is further composed of several blocks to totally indicate ten different scattering mechanisms. The excellent performance of this scheme is demonstrated by comparing it with the widely-used entropy/alpha classification, and a better discrimination of radar targets is obtained. ?VDE VERLAG GMBH ?Berlin ?Offenbach.

submitted time 2017-01-04 Hits787Downloads333 Comment 0

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