Study On Antenna For Multi-function Portable Electronic Taminals

Multi-function portable electronic terminal is a combination of communication terminaland information processing unit. With the rapid development of microelectronics and wirelesscommunication technology, multi-function portable electronic terminal has continued movingtoward the directions of miniaturization and multi-functional. In the future, it can be expectedthat everyone only needs such an intelligent and portable terminal for convenient working orrelaxing at any locations. As the "eyes" of multi-function portable electronic terminal, theantenna sits on the top layer of the system design, and has the most direct impact on thequality of wireless communication. Therefore, antenna for multi-function portable electronicterminals should have the characteristics of small size, multiband, and broadband.In this thesis, the characteristics of antenna for multi-function portable electronicterminals are analyzed first. Technical methods to realize miniaturized and multiband antennaare introduced. By considering the working band requirement of multi-function portableelectronic terminals, two novel antenna structures are proposed by theoretical analysis andnumerical simulation, which are suitable for low-frequency and high frequency combinationsof multi-function portable electronic terminals, respectively.Starting with the fundamentals of microstrip antennas and considering the characteristicsof low-frequency combinations for portable electronic terminal, the microstrip antenna whichcan work at900MHz,1800MHz,1900MHz and2.4GHz is designed. According to thedesign steps of the rectangular microstrip antenna, the antenna bandwidth at each band(VSWR <2or RL <-10) is7.7%,48.1%and29.0%, respectively, and a pass band ispresented in the middle. The human body model provided by SEMCAD is used to simulatethe specific absorption rate (SAR) of the designed antenna, and the simulation results indicatethat the SAR is much lower than the international standards.Fractal antennas have the characteristics of self-similarity, their resonant frequencychanges at a geometric ratio of the fractal structure, and their bands can be well controlled. Aquad-band antenna suitable for portable electronic terminals working at multibands of highfrequency is designed, which has the resonant frequency of2.4GHz,3.5GHz,5.2GHz and5.8GHz, respectively. The designed antenna has a nested structure with semi-elliptical rings.The bandwidth is17.9%,29.5%and45.6%, respectively, and a pass band is presented in thelast. These antenna bands have characteristics of large capacity and high data transmissionspeed.