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Junyu Shen - One of the best experts on this subject based on the ideXlab platform.
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miniaturized arbitrary Phase Difference couplers for arbitrary coupling coefficients
IEEE Transactions on Microwave Theory and Techniques, 2013Co-Authors: Yongle Wu, Junyu Shen, S W LeungAbstract:In this paper, a planar miniaturized arbitrary Phase-Difference coupler with arbitrary coupling coefficients is proposed. The proposed coupler consists of three coupled-line sections which achieves a compact circuit layout in microstrip implementation. The circuit parameters of this novel coupler can be easily determined by the derived closed-form equations and the corresponding performance analysis in terms of the bandwidth and miniaturization requirement is provided. Two prototypes with this proposed structure, operating at 2 GHz, have been designed and implemented using microstrip technology. One has a 45° Phase Difference with - 3-dB coupling coefficient and the other demonstrates a 60° Phase Difference with - 4.77-dB coupling coefficient. In addition, over 20% fractional bandwidth, which is defined as 5° Phase error and 0.5-dB magnitude imbalance, is obtained in both of the two prototypes.
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Comments on “Quasi-Arbitrary Phase-Difference Hybrid Coupler”
IEEE Transactions on Microwave Theory and Techniques, 2013Co-Authors: Junyu Shen, Yuanan LiuAbstract:A novel hybrid coupler with nonstandard Phase Difference has been reported recently by Wong in 2012, which shows promising potentials in applications like the feeding networks for Phased array antenna. However, it is found that the design equations of Wong are incomplete because of the neglect of an interrelated constrain between the design parameters ( $Z_{{2}}$ and $\theta_{{2}}$ ) and a constant relationship between the parameters ( $Z_{2}$ and $Z_{3}$ ). This letter rectifies the design formulas for this Phase-Difference hybrid coupler and demonstrates that the analytical solution for electrical parameters can be uniquely obtained to a certain Phase-Difference value. The bandwidths of the different Phase variations for general Phase-Difference coupler are presented. In addition, the analysis for the arbitrary coupling level and arbitrary Phase-Difference hybrid coupler is proposed and closed-form design equations are given.
Youn-soo Kim - One of the best experts on this subject based on the ideXlab platform.
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Phase-Difference of urban area in polarimetric SAR images
Electronics Letters, 2012Co-Authors: Kyung-yup Lee, Youn-soo KimAbstract:Proposed is a new Phase-Difference parameter for classifying urban areas in a polarimetric SAR image. First, the Phase-Difference characteristics of urban areas was analysed for various orientation angles. Subsequently it was found that the co-polarised Phase-Difference (CPD) is adequate for an aligned urban area, while the cross-polarised Phase-Difference (XPD) is the best parameter for a 45°-oriented urban area. Based on these analyses, the CPD was used for a small orientation angle (|thetas|≤π/8) and the XPD for a large orientation angle (|thetas|>π/8) to improve the accuracy of the urban classification in a polarimetric SAR image. This new technique was verified using polarimetric SAR image data sets (PALSAR and RADARST-2 images).
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New Phase-Difference for polarimetric SAR images
2011Co-Authors: Kyung-yup Lee, Youn-soo KimAbstract:Classification of urban areas in SAR images has always been a difficult task [1]. For urban area, however, backscattered signals in general are from single-bounce, double-bounce and multiple-bounce returns of various parts of the structure, although they are not from the defused scattering of a random media such as vegetation [1]. The orientation angle of scattering media affects the polarimetric radar signatures [2]. So Lee et al. [2] and Yamaguchi et al. [3] consider transformation of coherency matrix T 3 to model rotations about the line-of-sight. In this paper, we will present the Phase Difference characteristics of urban areas in polarimetric SAR (PolSAR) images and an improved classification algorithm for urban areas using the co-polarized Phase Difference (CPD) and cross-polarized Phase Difference (XPD).
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IGARSS - Phase-Difference characteristics of urban areas in polarimetric SAR images
2011 IEEE International Geoscience and Remote Sensing Symposium, 2011Co-Authors: Kyung-yup Lee, Youn-soo KimAbstract:We will present the Phase Difference characteristics of urban areas in polarimetric SAR (PolSAR) images and an improved classification parameter for urban areas using the co-polarized Phase Difference (CPD) and cross-polarized Phase Difference (XPD). This synthesis CPD and XPD is the first step to obtain the effective Phase Difference of urban areas.
E. D. Tereshchenko - One of the best experts on this subject based on the ideXlab platform.
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Phase and Phase-Difference ionospheric radio tomography
International Journal of Imaging Systems and Technology, 1994Co-Authors: V. E. Kunitsyn, Elena S. Andreeva, O.g. Razinkov, E. D. TereshchenkoAbstract:Variants of ray ionospheric radiotomography (RT) are considered: the Phase RT based on measuring the absolute Phase or the total electron content and the Phase-Difference RT based on measuring the Phase-Difference RT based on measuring the Phase Difference or Doppler frequency. The Phase technique is shown to give poor results with typical errors in determining the absolute Phase. The previously developed technique of the Phase-Difference RT is presented.©1994 John Wiley & Sons Inc
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Phase and Phase‐Difference ionospheric radio tomography
International Journal of Imaging Systems and Technology, 1994Co-Authors: V. E. Kunitsyn, O.g. Razinkov, Elena Andreeva, E. D. TereshchenkoAbstract:Variants of ray ionospheric radiotomography (RT) are considered: the Phase RT based on measuring the absolute Phase or the total electron content and the Phase-Difference RT based on measuring the Phase-Difference RT based on measuring the Phase Difference or Doppler frequency. The Phase technique is shown to give poor results with typical errors in determining the absolute Phase. The previously developed technique of the Phase-Difference RT is presented.©1994 John Wiley & Sons Inc
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Phase-Difference radiotomography of the ionosphere
Annales Geophysicae, 1992Co-Authors: Elena Andreeva, V. E. Kunitsyn, E. D. TereshchenkoAbstract:The radiotomography problem is considered to reconstruct global ionospheric structures using the signal of the Earth's orbital satellites. It is shown that the direct transition from methods derived in non-ionospheric fields of geophysics to ionospheric studies is rather difficult and the authors suggest a different approach to the reconstruction of the electron density with respect to the Difference between linear integrals of Phase-Difference radiotomography. A comparison of this method with the classical scheme with respect to Phase integrals has been made. An advantage of the suggested method is shown. Some results are presented as applied to the experimental data recorded in the auroral region and in the southern part of the subauroral region. The reconstruction results of the ionospheric structures in these regions are demonstrated. The results show that as applied to ionospheric studies the Phase-Difference radiotomography seems to be promising
Shao Yong Zheng - One of the best experts on this subject based on the ideXlab platform.
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An Arbitrary Phase-Difference Hybrid Coupler with Enhanced Bandwidth
2018 International Applied Computational Electromagnetics Society Symposium - China (ACES), 2018Co-Authors: Jia Min Wen, Shui Hong Wang, Shao Yong ZhengAbstract:The existing arbitrary Phase Difference hybrid couplers usually have limited bandwidths due to the much more complex requirements for implementing non-standard Phase Difference. To effectively extend the bandwidth of a two section branch line coupler with arbitrary Phase Difference, a coupled line section is utilized to replace the middle branch. For validation, two 3 dB couplers which provide 45° and 135° Phase Differences were designed and fabricated. They were measured to achieve wide bandwidths of 33.7% and 25% respectively.
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Quasi-Arbitrary Phase-Difference Hybrid Coupler
IEEE Transactions on Microwave Theory and Techniques, 2012Co-Authors: Yuk Shing Wong, Shao Yong Zheng, Shing ChanAbstract:Previous hybrid couplers have output Phase Difference that have either been 0°, 90°, or 180°. Other Phase Differences could only be realized using additional Phase-shift elements. This increased circuit size and cost, and also degraded overall performance due to interconnecting mismatch losses. The proposed uniplanar arbitrary Phase-Difference coupler eliminates these additional components, thereby maintaining small size and good performance. Theoretical analysis is presented here together with measured results for two microstrip couplers for verification.
Kyung-yup Lee - One of the best experts on this subject based on the ideXlab platform.
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Phase-Difference of urban area in polarimetric SAR images
Electronics Letters, 2012Co-Authors: Kyung-yup Lee, Youn-soo KimAbstract:Proposed is a new Phase-Difference parameter for classifying urban areas in a polarimetric SAR image. First, the Phase-Difference characteristics of urban areas was analysed for various orientation angles. Subsequently it was found that the co-polarised Phase-Difference (CPD) is adequate for an aligned urban area, while the cross-polarised Phase-Difference (XPD) is the best parameter for a 45°-oriented urban area. Based on these analyses, the CPD was used for a small orientation angle (|thetas|≤π/8) and the XPD for a large orientation angle (|thetas|>π/8) to improve the accuracy of the urban classification in a polarimetric SAR image. This new technique was verified using polarimetric SAR image data sets (PALSAR and RADARST-2 images).
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New Phase-Difference for polarimetric SAR images
2011Co-Authors: Kyung-yup Lee, Youn-soo KimAbstract:Classification of urban areas in SAR images has always been a difficult task [1]. For urban area, however, backscattered signals in general are from single-bounce, double-bounce and multiple-bounce returns of various parts of the structure, although they are not from the defused scattering of a random media such as vegetation [1]. The orientation angle of scattering media affects the polarimetric radar signatures [2]. So Lee et al. [2] and Yamaguchi et al. [3] consider transformation of coherency matrix T 3 to model rotations about the line-of-sight. In this paper, we will present the Phase Difference characteristics of urban areas in polarimetric SAR (PolSAR) images and an improved classification algorithm for urban areas using the co-polarized Phase Difference (CPD) and cross-polarized Phase Difference (XPD).
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IGARSS - Phase-Difference characteristics of urban areas in polarimetric SAR images
2011 IEEE International Geoscience and Remote Sensing Symposium, 2011Co-Authors: Kyung-yup Lee, Youn-soo KimAbstract:We will present the Phase Difference characteristics of urban areas in polarimetric SAR (PolSAR) images and an improved classification parameter for urban areas using the co-polarized Phase Difference (CPD) and cross-polarized Phase Difference (XPD). This synthesis CPD and XPD is the first step to obtain the effective Phase Difference of urban areas.
