Study And Application Of Built-in Microstrip Antenna For Mobile Communication Terminal

The increasing demand for multiple mobile radio communication services makes the need for compact multiple and broad frequency band antenna more and more urgent. For the microstrip antenna has the advantage of low profile and easily conformity with carrier, the research of terminal antenna on traditional microstrip antenna become hotter and hotter.As known the terminal built-in antenna technologies mainly involve miniaturization technology, multiple band and wide band technology. This paper emphasizes on how to achieve the characteristics of multiple band and wide band on the basis of the compact antenna through the antenna structure which is easy to fabricate and feeding method is as simple as possible. Meanwhile, how to make the structure flexible and has some general value is also the focus of this paper.The antenna miniaturization technologies are summarized firstly then the microstrip antenna loaded with short circuit is studied by cavity model theory when the antenna is completely sealed at the bridge of the patch. The size formulas of traditional rectangular antenna are corrected on the basis of the analysis and large amounts of simulations. Then the new empirical formulas are promoted and some explorations on miniaturization technology are made in this part. Meanwhile a sandwich structure antenna applied to GPS handhold terminal is designed.The following chapter systematically introduces frequency generation and wide band technologies. Then two types of antennas applied to mobile radio terminal is designed on the basis of PIFA by slot loading technology. It is important to point out that the frequency generation and wide frequency band technologies on the basis of compact antenna are the focus of this chapter. The first design is a terminal antenna can simultaneously work on GSM900, DCS1800 and ISM WLAN 2.4GHz bands. The relative impedance bandwidth of the bands is 6.5%, 7.5%, 3.4% completely covering the demanded band and the antenna has the same radiation pattern at the three bands. All these characteristics are achieved through a simple symmetrical double S-shaped slot array and this type of structure is easy to get wider bandwidth in other higher band. The second type of antenna is a built-in antenna applied to all WLAN bands and WiMAX bands. The relative impedance bandwidth of the three bands is respectively 17.2%, 8.9%, 12.1% and the antenna has high gain and same radiation pattern at most of the bands. A flexible Lin-shaped slot array is designed and this array is very easy to adjust the parameters of the slots to get new antennas applied to other mobile radio communications systems.