| Summary: | 博士 === 逢甲大學 === 電機與通訊工程博士學位學程 === 107 === This thesis is mainly composed of two topics. The first topic is an an-emometer and a wind direction meter that uses a pair of fiber Bragg grat-ings to simultaneously monitor wind speed and wind direction. Fiber an-emometers have the advantages of lightweight and simple design. Its components include plastic balls, stainless steel rods and two Bragg fiber gratings. The two gratings are spaced 90° apart and stick to the surface of the stainless steel rod. The wind force causes the stainless steel rod to bend and strain the Bragg fiber grating to produce a shift in grating wave-length. The wind speed and angle of wind direction according to the shift of the two grating wavelengths can be calculated by using the analytical model. The experimental results were obtained by a fiber anemometer with an actual wind speed in measuring resolution of 0.49 m/s. Wind an-gle error is approximately 0.69%. The error of wind speed is less than 2.38%, and the sensitivity is 0.02 nm / (m/s).
The second topic is a sensor for simultaneously measuring the tempera-ture and relative humidity. Using a polished fiber Bragg grating with a tilted angle of 3°, a polymer film of sodium acrylate polymer is applied on top of the polished fiber grating to simultaneously sense temperature and relative humidity. The experimental results have an approximately linear relationship with the wavelength shift of fiber grating core and cladding modes, and it shows the relationship between temperature and relative humidity.
Due to the need to integrate wired and wireless communications, addi-tional third topic of GPS and WLAN antennas have been studied and proposed in the appendix A. It is a circular slot antenna embedded in an open loop, which has a C-shaped feed band for dual band in CP and GPS / WLAN operating bands. The antenna is designed with a circular slot and includes of two C-shaped feed strips embedded in the ring and CPW to achieve 1.575 GHz (GPS) and 2.4 GHz (WLAN). The measurement of return loss impedance bandwidth under -10 dB, one is 392 MHz (26.5%) from 1.285 to 1.677 GHz, and the other is 347 MHz (13.8%) from 2.338 to 2.685 GHz. The antenna gain measured is 3.88 dBic at 1.575 GHz in the GPS band and 2.82 dBic at 2.4 GHz in the WLAN band. The 3 dB axis ratio bandwidth with two bands is measured, one is 105 MHz (6.6%) from 1.545 GHz to 1.65 GHz in the GPS band, and the other is 670 MHz (25.6%) from 2.28 GHz to 2.95 GHz in the WLAN band. The polariza-tion of the radiation pattern is RHCP.
In the future, a telecommunications room is a meteorological observa-tory and an environmental observatory. The telecommunications room is also the data integration center for fiber sensors. We expect to expand the last mile of fiber to the home (FTTH) in the telecommunications room, and set up an optical measurement system to measure the relevant data in the host room. By detecting the temperature and relative humidity, the air conditioner and the exhaust fan are controlled to be turned on or off to achieve energy saving and carbon reduction. It is a good idea and solution to put together the Bragg fiber grating anemometer/wind direction meter and GPS/WLAN antenna. The purpose is to assist in monitoring the qual-ity status of commercial antennas. Because most of the remote areas are unmanned base stations, the network management system actively and instantly detect the radio frequency status of the antenna. When the radia-tion pattern of the antenna is not good or the antenna is faulty, the per-sonnel can quickly reach the site processing and repair.
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