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101 results on '"Lee, Ching-Her"'

6. A dual-band branch-line coupler using quasi-composite right/left-handed transmission lines

Author

Jhuang, He-Kai, Lee, Ching-Her, Hu, Po-Min, and Hsu, Chung-I G.

Subjects
Telecommunications services industry -- Production processes, Communications industry -- Production processes, Circuit components -- Usage, Telecommunications services industry, Semiconductor device, Business, Electronics and electrical industries, Engineering and manufacturing industries, Telecommunications industry
Abstract

Advantages of using a quasi-right hand-left-hand duel band branch-line coupler in microstrip form, for circuit integration in course of dual-band operation are discussed.

Published
2006

8. Differentially fed dual‐band circularly polarized printed slot antenna with high common‐mode rejection.

Author

Lee, Ching‐Her, Huang, Jun‐Wei, and Hsu, Chung‐I G.

Subjects
*SLOT antennas, *ANTENNA radiation patterns, *WIRELESS LANs, *INTERFERENCE suppression
Abstract

This letter proposes a newly designed differentially fed dual‐band circularly polarized (CP) printed slot antenna (PSA). The antenna consists of two oppositely fed halberd‐shaped strips and an S‐shaped slot. By configuring the antenna structure in rotationally symmetric fashion, the fields radiated by any two rotationally symmetric parts of the CP PSA will be constructive when excited differentially and destructive when in common‐mode (CM) operation. Thus, good differential‐mode (DM) performance and high CM rejection can be achieved. In particular, in both CP bands the radiation patterns of the proposed antenna are of the same CP sense, and the CP beams are wide and stable. Measurement shows the proposed differentially fed dual‐band CP PSA has a lower (higher) 10‐dB DM impedance band of 2.09 to 2.85 (5.06‐5.89) GHz and a 3‐dB DM axial‐ratio band of 2.32 to 2.59 (5.13‐5.86) GHz, corresponding to a CP fractional bandwidth of 10.9% (13.3%). Besides, in the displayed frequency region of 2‐6 GHz, the CM signals can be effectively suppressed, with the measured CM return loss smaller than 2.96 dB. The conversion of DM input signals into CM reflected signals is even smaller, with the measured DM‐to‐CM conversion less than −32 dB. [ABSTRACT FROM AUTHOR]

Published
2021
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18. Differentially fed CP antenna with quasi‐self‐complementary semicircular‐ring structure.

Author

Lee, Ching‐Her, Hong, Wan‐Chu, Chen, Wen‐Jie, and Hsu, Chung‐I G.

Subjects
*BROADBAND antennas, *MULTIFREQUENCY antennas, *ANTENNA design, *ANTENNA radiation patterns, *IMPEDANCE matching, *RADIO frequency, *REFLECTANCE
Abstract

This article presents a new design of a common‐mode suppressed differentially fed circularly polarized (CP) antenna using a quasi‐self‐complementary (QSC) structure. The antenna radiating element consists of a semicircular‐ring radiating patch and its complementary radiating slot counterpart. The design idea for producing CP radiation is based on field orthogonality of the QSC structure. For better impedance matching, a fan‐shaped notch (stub) around the feeding position was cut from (implemented in) the semicircular radiating patch (slot). In addition, to improve the axial ratio, a QSC semielliptical structure is embedded in the central area of the antenna. For the designed differentially fed CP antenna, measurement shows that the differential‐mode (DM) operating band with return loss >10 dB covers 4.76‐6.38 GHz. The measured DM 3‐dB axial‐ratio band is 4.95‐5.43 GHz. Also, very good common‐mode (CM) suppression is observed with the measured CM reflection coefficient >−1.21 dB in 4.50‐6.5 GHz. [ABSTRACT FROM AUTHOR]

Published
2019
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22. Design of balanced power divider with wide common-mode suppression band.

Author

Lee, Ching‐Her, Hsu, Chung‐I G., and Chen, Wen‐Xuan

Subjects
*POWER dividers, *MICROSTRIP transmission lines, *BANDWIDTHS, *DIVIDING circuits, *STRIP transmission lines
Abstract

In this paper, a balanced power divider (PD) is designed and implemented in a three-layer configuration. It consists of two tightly stacked microstrip Wilkinson PDs with a shared ground plane in the middle layer. With both dumbbell-shaped and partially interdigital open-ended slots embedded in the common ground, the designed balanced PD can yield a high common-mode (CM) suppression level over a very wide frequency band without degrading the differential-mode (DM) performance. A close examination of this design reveals that good CM suppression mainly comes from the blocking of the ground-plane current path by the open-ended slots in the ground plane. In addition, the proposed balanced PD also exhibits a very wide CM isolation band. A prototype of the proposed balanced PD is realized. The measured fractional frequency bandwidth for CM suppression is 68% and for CM isolation is 93%. [ABSTRACT FROM AUTHOR]

Published
2018
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