| Narrow Band Internet of Things(NB-IoT)is one of the emerging technologies in the field of Internet of Things in recent years.It has been applied to many kinds of vertical industries,showing exponential growth due to its advantages of low power consumption,wide coverage,low cost,and large capacity.As the critical component of NB-IoT system communication,NB-IoT antenna directly affects the communication quality and efficiency of NB-IoT system.The NB-IoT system has the characteristic of dual-band communication and covers a wide frequency range.The NB-IoT antenna is required for dual-band and broadband operation.Therefore,the study on dual-band broadband technology of NB-IoT antenna has important practical application value.Combining with the study on dual-band broadband technology of NB-IoT antenna,this thesis has designed a dual-band NB-IoT antenna and a dual-band broadband NB-IoT antenna.The main work contents are summarized as follows:1.The basic performance parameters of the antenna and its calculation formula,the relevant theoretical basis of the microstrip antenna,including its definition,common types,feeding mode,and radiation mechanism have been studied.This provides a theoretical basis for the antenna design and paves the way for it.2.The related technologies to realize dual-band characteristic of microstrip antenna have been studied,and a monopole NB-IoT dual-band antenna has been designed.The designed antenna is a monopole antenna with a double-branch structure,and the bending line technology is adopted in the longer branch,achieving great dual-band characteristic.The antenna's measured-6dB return loss bandwidths are 760MHz~971MHz(211MHz)and 1512MHz~2050MHz(538MHz),covering the communication band of NB-IoT system(825MHz~960MHz and 1725MHz~1860MHz),and the antenna has the omnidirectional characteristic.The antenna also has the remarkable features of simple structure,small size,and convenient fabrication.3.The related technologies to realize the broadbandization of microstrip antennas have been studied,and a wide-slot NB-IoT dual-band broadband antenna has been designed.The designed antenna is selected as a wide slot antenna,which adopts a wide rectangular radiator structure to play the role of tuning;and a rectangular patch is added into the rectangular wide slot to make it a U-shaped slot,which changes the coupling relationship between them to ultimately achieve dual-band and broadband characteristics of the antenna.The antenna's measured-10 dB return loss bandwidths are 1.07GHz~2.55 GHz and 3.27GHz~6.44 GHz,and the return loss in the band of NB-IoT system(825MHz~960MHz and 1725MHz~1860MHz)are all below-7.5dB;-10 dB return loss bandwidths cover WLAN and Bluetooth bands,which realizes the dual-band characteristic of the antenna.In the dual bands with return loss below-10 dB,the relative bandwidths of the antenna are 92.5% and 61.9%,respectively,and the antenna realizes the broadband characteristic.Finally,communication function verifications for the designed NB-IoT dual-band broadband antennas are carried out in this thesis.The results indicate that the designed NB-IoT dual-band broadband antennas can be well applied to the communication bands of NB-IoT system,satisfying the communication needs of NB-IoT system. |
PDF Full Text Request