| With the rapid development of mobile communication systems,antenna,as the forefront of the mobile terminal equipment,plays an important role in it.Thus,people have gradually put forward higher requirements for mobile terminal antennas.Due to the emergence of the various new communication system standards,terminal antennas that work in multiple frequency bands have important research value.This thesis focuses on the research of omnidirectional high-gain antennas operating at the 2.4/5 GHz WLAN band and multi-band metal-frame MIMO smartphone antennas.In order to further verify the feasibility and accuracy of the designs,the above antennas were processed and measured.The research contents mainly include the following aspects:1.Two omnidirectional high-gain dipole array antennas operating at the 2.4/5 GHz WLAN frequency band are proposed.In this design,the microstrip feed line is used to connect the three dipoles in the form of the series-parallel feed.The double branches on the dipole unit are used to realize the dual-band design of the antenna.The currents on the different antenna units are in phase by adjusting the spacing between the units and adding additional U-shaped branch,which can achieve the high gain characteristic.The size of the un-miniaturized antenna is large,so a miniaturized dipole array antenna is designed by using the half-cutting technique,which reduces the size of the antenna by about 46%.The measured results of the two antennas are in good agreement with the simulated results,and the antennas can cover the required bands.Besides,the design has the advantages of simple structure,small size,easy processing,and low cost.Thus,the proposed antenna is very suitable for engineering applications.2.An omnidirectional high gain dipole antenna with parasitic patches is proposed.The highorder mode of the dipole ensures that the antenna can operate in the 2.4/5 GHz WLAN band.By adding three types of parasitic patches with different sizes at appropriate positions on both sides of the dipole,the coupling between them will be produced,which can make the parasitic patches have the radiation characteristic.Meanwhile,the parasitic patches can generate opposite current to the adjacent part of dipole,so as to make the overall current of the antenna consistent and improve the gain of the antenna.The measured peak gains in the lower and higher bands are greater than 3.81 d Bi and 7.88 d Bi,respectively.In addition,the antenna has good omnidirectional radiation characteristics.3.A MIMO mobile phone antenna with metal frame working in the 4G/5G frequency band is proposed.The design consists of six antenna elements,the two of which loaded on the long sides are half-loop mode and work in the GSM850/900(824-960 MHz)band.The other four antennas loaded on the corner can work in two states by using reconfigurable technology: 1)When switch 1 turns on and switch 2 turns off,the antennas work in state 1 as IFA antennas.The four antennas all work in DCS/PCS /UMTS2100 and LTE2300/2500 frequency bands(1710-2690 MHz);When switch 1 turns on and switch 2 turns off,they work in state 2 as 1? loop antennas.All four antennas work in the Sub-6G 5G frequency band(LTE 42/43,3400-3800 MHz).The measured isolations between the six antenna elements are greater than 12.8 d B,which meet the design requirements.In addition,the other measured performances are good.It is worth emphasizing that the clearance of the antenna is only 2 mm.Thus,it has good potential in high screen proportion mobile phones. |
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