Browsing by Author "Tarn, I-Young"

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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 new advance in circular polarization selective surface - A three layered CPSS without vertical conductive segments
(2007-02-01)
Tarn, I-Young
;
Chung, Shyh-Jong
;
電信工程研究所
;
Institute of Communications Engineering
Investigations into a surface that reflects one sense of circularly polarized electromagnetic wave but transmits the other, namely a circular-polarization selective surface (CPSS), were carried out. This paper presents CPSS using simple planar structure without any vertical conductive segments. Couplings, through the use of L-shaped traces, were produced to replace the vias. Operational principle and design procedure are developed, thus the optimal design parameters are found. Also presented are the results of numerical computations and measurements for "isolation" and "transmission loss". A 30 GHz example demonstrates the performances of the design and the attractiveness in millimeter-wave circular polarization selectivity applications.
A Novel Pattern Diversity Reflector Antenna Using Reconfigurable Frequency Selective Reflectors
(2009-10-01)
Tarn, I-Young
;
Chung, Shyh-Jong
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電信工程研究所
;
Institute of Communications Engineering
A radiation pattern diversity reflector antenna is investigated. Novel switchable frequency selective reflectors are designed and developed to construct a square corner reflector antenna. By controlling a switching device on the frequency selective reflector, one can make it opaque or transparent to a vertically polarized incident wave. This antenna is fed by a monopole. By configuring the switch states of the frequency selective reflectors, various beam shapes can be formed and steered. Measured results of the antenna show good agreement with the calculated ones.
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 a planar ultrawideband antenna with a new band-notch structure
(2007-12-01)
Hong, Chong-Yu
;
Ling, Ching-Wei
;
Tarn, I-Young
;
Chung, Shyh-Jong
;
電信工程研究所
A novel planar ultrawideband (UWB) antenna with band-notched function. The antenna consists of a radiation patch that has an arc-shaped edge and a partially modified ground plane. The antenna that makes it different from the traditional monopole antenna is the modification in the shape of ground plane, including two bevel slots on the upper edge and two semicircle slots on the bottom edge of the ground plane. These slots improve the input impedance bandwidth and the high frequency radiation performance. With this design, the return loss is lower than 10 dB in 3.1-10.6 GHz frequency range and the radiation pattern is highly similar to the monopole antenna. By embedding a pair of T-shaped stubs inside an elliptical slot cut in the radiation patch, a notch around 5.5 GHz WLAN band is obtained. The average gain is lower than -18 dBi in the stopband, while the patterns and the gains at frequencies other than in the stopband are similar to that of the antenna without the band-notched function.
Dual-mode millimeter-wave folded microstrip reflectarray antenna
(2008-06-01)
Tarn, I-Young
;
Wang, Yu-Shin
;
Chung, Shyh-Jong
;
電信工程研究所
;
Institute of Communications Engineering
A dual-mode folded microstrip reflectarray antenna was developed and demonstrated in this paper. The proposed folded reflectarray antenna contains three parts: a planar main reflector, a planar subreflector, and printed feed antennas. The main reflector is used to produce twisted reradiated fields and to provide phase compensation for focusing. The subreflector parallel with the main reflector is made of a substrate printed with high-density metal grid lines, which is transparent to perpendicularly polarized fields, but would reflect the parallel ones. Three fixed-position patch antennas with polarization parallel to the grid lines are created for the radar mode, so that the radiation beam is switchable. Another patch with perpendicular polarization is designed for communication. A simple approach was proposed for simulating and designing the folded reflectarray. Measured results show good agreement with the calculated ones.