| Summary: | 碩士 === 明新科技大學 === 電機工程研究所 === 102 === In this thesis, we study and fabricate three kinds of the dipole antenna which are rectangular planar dipole antenna, rectangular planar dipole antenna with meander line, and tubular dipole antenna.
We developed the rectangular planar dipole antenna which can be applied to 1800 MHz and 2400 MHz by adjusting the antenna width W and middle gap of the dipole antenna. When the ratio length/width of antenna equals 2 and the middle gap of the dipole antenna equals 1.5 mm, higher bandwidth of designed antenna can be obtained. The RO4003C substrate is also used in this study to enhance the bandwidth and reduce the return loss of rectangular planar dipole antenna.
The rectangular planar dipole antenna with meander line is also designed. The available frequency ranges include 793.80~1001.98MHz which can be applied to GSM900 system, 1567.30~2162.20MHz which can be applied to GSM1800 system, and 2207.58~2553.85MHz which can be applied to RFID and Bluetooth system.
The tubular dipole antenna is also implemented. This wideband tubular dipole antenna can be used in GSM and GPS frequency bands. Changing the tubular dipole antenna parameters of length, outside diameter, inside diameter and tubular materials are studied to observe the variations of bandwidth and gain of the tubular dipole antenna. Six different industrial plastics such as PMMA, PE, POM, PVC, ABS, and Bakelite are used to change the tubular material. It can be observed that the smaller dielectric constant of tubular material will increase the impedance bandwidth of the tubular dipole antenna. The fabricated PVC tubular dipole antenna with length L = 60 mm and outside diameter of tubular material 18 mm can obtain the wide bandwidth about 1117 MHz. The return loss and peak gain of the fabricated tubular dipole antenna are -16.89dB and 5.19dBi at 900MHz, -36.14dB and 4.13dBi at 1575MHz, -11.74dB and 4.43dBi at 1800MHz . This antenna can be used in GSM and GPS communication systems.
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