| Nowadays,the high-speed and large-capacity of information transfer and the multistandard and multi-functional communication requirements promotes the development of wireless communication systems towards the direction of high integration and high portability.Based on these new trends in current wireless communication systems,this thesis focuses on wide-band antennas,dual-band antennas,and antenna miniaturization technologies.The focus of the corresponding research is divided into the following two parts:(1)Research on the miniaturized loading antenna of wideband antenna.The focus of this research is a planar rectangular monopole antenna fed by a coplanar waveguide.First,a pair of symmetrical stubs are extended from the ground planes on both sides of the coplanar waveguide,and then the impedance of the antenna is adjusted by adjusting its length to achieve wide-band operating characteristics;then,the loaded stubs are bent inward to form L-shaped stubs,which surround the monopole radiation patch,and finally the length of the bends are adjusted to reduce the long side of the antenna size,to achieve the purpose of miniaturization.The comparison results show that the overall area of the antenna is reduced by 46.7%,and its operating frequency range is from 3.1 GHz to 11 GHz(absolute bandwidth is 7.9 GHz),which completely covers the UWB communication frequency band and has stable omnidirectional radiation characteristics in the frequency band.(2)Research on the dual-band miniaturized antenna based on left-handed materials.The study is based on a deformed printed T-shaped monopole antenna,and a pair of symmetrical left-handed material structures are loaded on both sides of the microstrip feeder,which are on the same layer as the antenna;the structure is composed of two pairs of interleaved bending lines connected by stubs,in addition to improving the radiation performance of the antenna,it can also be used as a parasitic unit to generate a new operating frequency band for the antenna,thereby achieving dual-band operating characteristics.The size of the left-hand material structure used here is only one tenth of its operating wavelength,and it does not occupy additional antenna space,which is conducive to miniaturization design.The test results show that the working frequency bands of the antenna satisfy the 2.43?2.47 GHz and 3.18?3.70 GHz bands of WLAN and Wi MAX communications,respectively,and have an omnidirectional radiation pattern in the frequency bands. |
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