Browsing by Author "Lee, Yun-Jui"

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A Compact Design of Antenna Feed for 6 M S/X-Bands Mono-Pulse Auto-Tracking Ground Station
(2015)
Lee, Yun-Jui
;
Huang, Vincent
;
Yang, Ru-Muh
;
Hsu, Ti-Hsiang
;
Chen, Ming-Hui
A compact S-band auto-tracking antenna feed for 6 m mono-pulse auto-tracking ground station is presented. It is designed to reduce the effect of blockage of the antenna systems and modify the orientation angle of the main reflector to align antenna boresight with a satellite. A circular waveguide is designed to connect to the septum polarizer for communication between the earth and LEO satellite. Based on the circular waveguide as an inner metal, a cylindrical metal is added as an outer metal to form a coaxial line for tracking LEO satellite. The uplink band of the antenna feed is from 2.025 to 2.12 GHz and the downlink band is from 2.2 to 2.3 CHz. The results show that the antenna gain of 6 m reflector is about 39.7 dBic and the 1-dBbeamw idth is 1 degree. The polarization isolation between sum and difference patterns is larger than 30 dB, and the axial ratio is lower than 1.1 dB within +/- 0.5 degree range.
A Compact Dual-Band Filtering Microstrip Antenna with the Same Polarization Planes
(2012-01-01)
Lee, Yun-Jui
;
Cao, Gang-Wei
;
Chung, Shyh-Jong
;
電信工程研究所
;
Institute of Communications Engineering
A novel compact dual-band filtering antenna operated in WLAN bands is presented. The proposed design is composed of a slot-loaded patch and a half-wavelength steppedimpedance resonator with the same apertured ground. Fullwave simulator HFSS is used to extract the coupling coefficients in order to determine the physical dimension of the apertures. The antenna provides good selectivity and the same polarization planes in 2.4 GHz and 5.2 GHz bands. The measurement results agree with the simulated ones.
A Compact Dual-Band Filtering Microstrip Antenna with the Same Polarization Planes
(2012-01-01)
Lee, Yun-Jui
;
Cao, Gang-Wei
;
Chung, Shyh-Jong
;
傳播研究所
;
Institute of Communication Studies
A novel compact dual-band filtering antenna operated in WLAN bands is presented. The proposed design is composed of a slot-loaded patch and a half-wavelength steppedimpedance resonator with the same apertured ground. Fullwave simulator HFSS is used to extract the coupling coefficients in order to determine the physical dimension of the apertures. The antenna provides good selectivity and the same polarization planes in 2.4 GHz and 5.2 GHz bands. The measurement results agree with the simulated ones.
A Filtering Diplexing Antenna for Dual-Band Operation With Similar Radiation Patterns and Low Cross-Polarization Levels
(2017-01-01)
Lee, Yun-Jui
;
Tarng, Jenn-Hwan
;
Chung, Shyh-Jong
;
電信工程研究所
;
Institute of Communications Engineering
A novel filtering diplexing antenna for dual-band operation is presented. The antenna is composed of a slot-loaded patch and two resonators with a commonly used ground. Dog-bone-shaped slots are used on the ground for achieving broadside magnetic coupling and increasing the isolation between operating bands. The antenna design is based on a second-order Chebyshev bandpass filter synthesis. The proposed antenna exhibits high band-edge selectivity performance, low cross-polarization levels with half-power beamwidths greater than 86 degrees for 2.4- and 5.2-GHz WLAN communication bands. The measured and simulated results are highly consistent.
A Low Cost C-band SAR Small Satellite Definition for Disasters Management
(2014)
Yaung, James Yu-Chen
;
Chung, Shyh-Jong
;
Lee, Yun-Jui
;
Tarn, I-Young
;
Wu, Bor-Han
Monsoons and typhoons bring along heavy precipitation and they can cause significant disasters in Taiwan in addition to earthquakes. Ever since a small satellite SAR mission was defined and published in APSAR2011 [1], the mission has been analyzed for seeking a feasible development solution with little critical technolgoy item. This work revealed a C-band small satellite payload definition solution and it was published in APSAR2013 [2]. Now, a skilful power combining technique using GaN SSPA products is identified as the enabling technology to substantiate the C-band system defined. Consequently, a satellite definition work has been initated in NSPO.
A Small Satellite C-band SAR Mission Payload Definition for Disasters Management
(2013)
Yaung, James Yu-Chen
;
Chen, Kun-Shan
;
Chung, Shyh-Jong
;
Yu, Shiann-Jeng
;
Hung, Hao-Lun
Taiwan is an island with various high mountains created by tectonic plate collision where continent building is still active with numerous earthquake activities. Taiwan is also in one of the most prevalent monsoon and typhoon areas and they can bring along heavy precipitation that produce great threat of mud slide and land slide in the mountains. Remote mountain areas can only rely on satellite monitoring before, during, and after heavy rains where the optical monitoring satellites won\'t be able to provide the timely data or information. SAR satellites, with their advantages of all-weather capability, repeat pass, fine spatial resolution and wide swath, can provide coverage at disaster locations in the island, disaster assessment and resource survey provided the operating frequency to be lower enough as indicated in the low cost C-band SAR satellite payload defined in this paper. Based on the payload technology tradeoff analysis, the C-band system with GaN SSPA power amplifier was selected by comparing it with the X-band system with the TWTA technology which was described in our early stage of mission definition and analysis.
An X-Band Circularly Polarized Antenna for Satellite Applications
(2014)
Lee, Yun-Jui
;
Lu, Joul-Hung
;
Tarn, I-Young
;
Chen, Shiou-Li
;
Chung, Shyh-Jong
An X-band right-hand circularly polarized antenna for satellite communication is presented. The antenna is composed of four conductive arms which wrap around each other in a helical manner. A feeding network adopted for this design consists of one T-shaped power divider and two branch line couplers. The measured 3-dR AR-bandwidth is 5.4%. The antenna gain of circularly polarized pattern is 8.76 dRic and 3 dB beamwidth is larger than 60 degree.
Design of Antenna Feed for Mono-pulse Auto-Tracking Ground Station
(2014)
Lee, Yun-Jui
;
Chen, Wei-Lin
;
Yaung, Shan-Kuo
;
Yang, Ru-Muh
;
Chen, Ming-Hui
An S-band auto-tracking antenna feed for mono-pulse ground station is presented. The uplink band is from 2.025 to 2.12 GHz and the downlink band is from 2.2 to 2.3 GHz. The feed is utilized to modify the orientation angle of the antenna to align antenna boresight with a satellite. According to the mono-pulse radar theory, the system structure can be divided into two parts, sum and difference channels. Sum channel is used for data transmission and the key component is a septum polarizer which generates circularly polarized electric fields. Difference channel is used to modify the antenna angle and the key component is a TE21 tracking coupler with signal combining circuits. The results show that the polarization isolation is larger than 40 dB, and the axial ratio is smaller than 1.4 dB.