Browsing by Author "Lin, Ke-Wen"

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Receiving Performance Enhancement of Active GPS Antenna with Periodic Structure
(2011)
Lin, Han-Nien
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Lin, Ke-Wen
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Kuo, Chung-Wei
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Huang, Yu-Jie
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電信工程研究所
The purpose of this study is to design the high gain active GPS antenna module and analyze the performance improvement implemented with periodic structure. Since the utilization of high-impedance surface of periodic structures as reflector not only significantly reduces the antenna profile with phase enhancement, but it will also enhance its gain and directivity performance. We first investigated the electromagnetic radiation suppression characteristic of Electromagnetic Band-Gap (EBG) structure and utilized the microstrip measurement method to verify the simulation result for required stopband and performance. In this study, we design microstrip antenna and periodic structure with center frequency at 1.575 GHz for Global Positioning System (GPS) to investigate the effect with applications of EBG structure on antenna. Microstrip antenna has the industrial demanding characteristics of light weight, low profile, and easy integration with circuits on PCB. We investigated surface wave suppression and axial ratio improvement with the antenna surrounded by matching resonant EBG structure. Finally, we design the front-end low noise amplifier (LNA) with center frequency at 1.575 GHz to integrate with antenna to further improve GPS receiving sensitivity.
Use of Frequency Selective Surface to Prevent SAR and Improve Antenna Performance of Cellular Phones
(2011)
Lin, Han-Nien
;
Lin, Ke-Wen
;
Chen, Sheng-Chun
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The purpose of this study is to design the low-cost planar inverted-F antenna (PIFA) applicably built in cellular phones with finite integration technique (FIT) for simulation of surface current distribution, radiation efficiency, radiation pattern, and gain. The prototype antenna is constructed with aluminum foil and low-cost FR4 PCB substrate. The antenna is designed with quarter wavelength (lambda/4) of resonant frequencies and fed with 50 Omega matching microstrip. It owns the industrial demanding characteristics of light weight, compactness, low profile, and easy fabrication. The target frequency band is designed for the following cellular phone systems: GSM (Global system for mobile communication: 880-960 MHz), DCS (Digital communication system: 1.71-1.88 GHz, PCS (Personal communication system: 1.85-1.99 GHz), and IMT-2000 (3G: (1.92-2.17 GHz). However, since the bio-effect of specific absorption rate (SAR) by cellular phone gains popular concern, we also try to utilize the unique band-stop or band-pass features of frequency selective surface (FSS) to reduce the SAR. Finally, we design the finite size 2-dimensional periodic structure to integrate with antenna for SAR reduction by decreasing backward radiation. The result shows that the integrated PIFA-FSS module not only reduces the SAR but also improve the antenna gain and radiation efficiency of the cellular phone.