| Summary: | 碩士 === 亞東技術學院 === 資訊與通訊工程研究所 === 99 === In recent years, the mobile communication has developed vigorously；therefore, many different kinds of value-added applications are being put out constantly.
The paper designed the antennas simulated by GEMS software which adopted FDTD algorithm to provide for using in three different communication systems and discussed different conditions of the antennas applying to three different communication systems.
First of all, in DECT communication system, this research used two different types of dipole antennas which were designed on basis of 1900MHz bandwidth to compare each other , and the difference between them is the way of feed-in.
Additionally, in GSM communication system, this research used four types of multi-band dipole antennas which were designed on basis of different bandwidths, including 850MHz,900MHz,1800MHz and 1900MHz to discuss how the widths of antennas impacted on the radiation efficiency of antennas and how different shapes impacted on antennas. Meanwhile, this research compared the TIS and TRP of the testing result of above mentioned multi-band dipole antennas with that of general antennas in the market, and this experimental result showed the efficiency of the antennas this research designed is much better.
Furthermore, in CDMA2000 communication system, this research designed a PIFA antenna, and this PIFA antenna took advantage of different structure to increase its bandwidth. According to the measurement, in the operating frequency of CDMA2000, the efficiency of the radiation is between forty percent and seventy-five percent.
Finally, there are three parts in the fifth chapter and it mainly simulated how human body influenced on radiation of antennas and analyzed SAR. First part is to design a bow-tie antenna whose bandwidth is from 470MHz to 862MHz to apply to DVD-T. Moreover, this part simulated and analyzed the radiation conditions by putting the bow-tie antenna on single antennas, clothes and backpacks and measuring the respective distance between these objects and human body, and the experiment showed the result of putting the bow-tie antenna on backpacks is better than putting it on antennas and clothes.
Second part is to design a dipole antenna at 900MHz to simulate and analyze the radiation conditions by putting it on the waist of human body in vertical and horizontal way. According to the result, the contact area between the antenna and human body is smaller when putting the antenna on human body in vertical way; therefore, the effect on the efficiency of the antenna is smaller.
The last part is to design a dipole antenna at 850 MHz to simulate and analyze how human body influenced on the radiation conditions of antennas, practically measured SAR and temperature variation of objects. According to the result, when the antenna is closer to human body, the result had more influence on communication quality and SAR. In addition, when the distance is appropriate, human body is like a reflected surface and the gain and communication quality of the antenna increased.
Finally, the last chapter is to discuss and analyze the results. In addition, this research has achieved to improve communication quality and reduce influence from electromagnetic waves on human body.
|
|---|
