| This paper summarizes the development of the modern communication technology and the latest developments in mobile phone antenna, then it introduces the basic principle of radiation and the main electrical parameters of the antenna. The main study of this paper are designing two single antennas which cover the low bands and high bands, we integrate them into a multi-band antenna which band can cover both low and high bands.1. A rectangular slot antenna is designed. Firstly, we analysis the structure of rectangular microstrip antenna, study the influence of the bandwidth by change its structure size; Secondly, we change the structure of the rectangular microstrip into equivalent line and optimize its size, its bandwidth is 950-1350 MHz and resonant frequency is 1GHz; Finally, in order to reduce the resonant frequency of antenna,a rectangular slot is added. The bandwidth of the improved antenna is 810-1120 MHz by the return loss lower than-6dB covering GSM850 and GSM900.2. A UWB antenna with the combined slot is designed. Firstly, we analysis the structure of a UWB antenna with the rectangular microstrip and study the effect of the bandwidth by annlysising size and position of the slot; Secondly, we change the structure of the antenna by adding a rectangular patch into the circular patch, it can broadens the bandwidth of and reduces the area of the antenna on the circuit board; Finally, we optimize the size of the antenna, its bandwidth is 1.55-11 Ghz which can cover including GPS/DCS1800/PCS1900/UMTS2000/LTE2300/LTE2500/Bluetooth/WiMAX/UWB.3. A nine-bands multi-band antenna is designed. The antenna consists of two previous single-antenna which are printed in the upper and lower ends of the circuit board, they incentive respectively the low bands and high bands. In order to select the proper feeding location, we study the influence of feed location on bandwidth, then we optimize feed location and the size, its band is 0.81-1.12GHz/1.65-2.9Ghz/3.44-4.72 GHz covering GSM850/GSM900/DCS1800/PCS1900/UMTS/LTE2300/LTE2500/Bluetooth/WiMAX. |
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