Establishment of Equivalent Circuit Model of Small Antennas and Application

• Main Authors: Shih-Hung Lee, 李世宏
• Other Authors: Dau-Chyrh Chang
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/65806175446659164831

碩士 === 大葉大學 === 電信工程學系碩士班 === 93 === The impedance matching of the small antennas and planar invert F antennas(PIFA) will be discussed in this paper. Use the theory of transmission line and RF circuit to build simple electric circuit model. It can save time during antenna development. These results can be applied to the body temperature sense system, the automobile tire pressure sense system, the three bands communication system, the IEEE802.11a/b/g WLAN (wireless LAN), and the combination of GPS (global position system) and the IEEE802.11b/g WLAN. For the body temperature sense system, the antenna size is 34 mm by 28 mm. The operating frequency of antenna module is from 424 MHz to 444 MHz. The bandwidth is 20 MHz. The pattern of antenna is near omni-direction. The measurement of antenna gain is -18 dBi. For the automobile tire pressure sense system, by using the characteristic of temperature insensitive LTCC (Low Temperature Core-fired Ceramic) antenna, this antenna can be applied to the automobile tire pressure sense system. The operating frequency is from 430.2 MHz to 436.9 MHz. The bandwidth is 6.9 MHz. The pattern is near omni-direction, and the measured gain is -29 dBi. For the three bands communication system (900 MHz for GSM, 1800 MHz for DCS, and 1900 MHz for PACS), the antenna size is 29 mm by 21 mm. The advantages of antenna are small size, light weight and low cost. The bandwidth for 900 MHz and 1800 MHz to 1900 MHz are 40 MHz and 250 MHz respectively. The antenna gains are between 0.41 dBi and 0.45 dBi. For dualband IEEE802.11a/b/g WLAN application, the antenna size is only 11 mm by 9 mm. The bandwidth of 6 dB return loss for 2.4 GHz is from 2.16 GHz to 2.58 GHz, and the bandwidth for 5.25 GHz is from 5 GHz to 5.48 GHz. The bandwidth for 2.4 GHz and 5.25 GHz are 420 MHz and 480 MHz. The antenna gain of 2.45 GHz and 5.35 GHz are 1.2 dBi and 3.97 dBi respectively. For GPS (1575 MHz) and IEEE802.11b/g WLAN system, the size is 25 mm by 25 mm. The frequency of GPS and WLAN are from 1.544 GHz to 1.588 GHz and 2.36 GHz to 2.52 GHz. The antenna gain of GPS and WLAN are -3.18 dBi and 3.32 dBi respectively.