Research On Compact Size Antenna For Mobile Terminal Application

Nowadays, the trends on small mobile terminal devices are intelligent, ultra-thin, large screen and multiple communication systems. The features of intelligent devices bring convenience and fashion to users, which, however also bring unprecedented challenges to antenna design. The electrical performances of small mobile terminal device are largely depends on the quality of its antenna’s performance. Therefore the research and design of high-performance antenna have important practical significance.The article focuses on small-size, multi-frequency and printed mobile antenna. We mainly use couple-feeding and double-sided structure to achieve small-size, wideband and multiband. And we utilize etching slots on the ground to improve the isolation between the MIMO antenna elements, which solves the high correlation problem caused by the small size in MIMO mobile antenna. The main works as follows:Firstly, an overview of the development of single antenna and MIMO antennas for mobile application is introduced, and a brief introduction and analysis to the several excellent techniques proposed in other article is given.Secondly, we analyze the basic theory of micro-strip antenna, the main parameters and radiation theory, which will provide a theoretical basis for future research work. Then we design two small size multiband antennas and a MIMO antenna for mobile application. The main technical as follows:1. Couple-feeding is used to generate one-eighth wavelength resonant frequency. And double-sided structure is used to improve the bandwidth of the antenna. Then the small antenna covering seven bands for mobile application is obtained. The size of the antenna is only 15×25mm2, and the working bands are 824MHz-960 MHz and 1710MHz-2690 MHz, which cover LTE2300/2500/GSM850/900 /DCS1800/PCS1900/UMTS2100. Further, the frequency can be controlled independently.2. Several branches are used together to generate six resonance points. Three resonance points are in the band of 698MHz-960 MHz, the other three resonance points are in the band of 1710MHz-2690 MHz. A folded strip is added at one branch to improve impedance matching at high frequency band. And a notch is cut from the printed circuit board to improve impedance matching at low frequency band. Then working bands cover LTE700/2300/2500 /GSM850/ 900/DCS1800/PCS1900/UMTS2100.3. Couple-feeding technique is used to design an antenna that covers 1710MHz-2690 MHz, which serves as an element of MIMO antenna. On the basis, decoupled network is designed at the feeding line. Slots and neutralization lines between the two antenna elements are used together to reduce the relevance. Each method achieves decoupling at different frequency bands, thus a MIMO antenna for mobile application is obtained.4. The antenna structure(above 1) and the decoupling method(above 3) are utilized with other decoupling methods to design a MIMO antenna that covers 824MHz-960 MHz and 1710MHz-2690 MHz for mobile phone application.