| With the advent of the age of big data,people have put forward higher requirements for the transmission speed and quality of communication data,and the application environment of wireless communication systems has become more and more complicated.At the same time,it also faces the problem that the communication subsystem of the same platform is getting denser,that is,the antenna is getting denser.If the antenna's frequency characteristics or radiation characteristics can be changed as needed according to the application scenario,then these problems will be alleviated to a large extent.Under this background,reconfigurable antennas came into being.Compared with traditional antennas,the basic structure of the antenna itself remains unchanged.The difference is that the reconfigurable antenna can change the radiation structure of the antenna through mechanical methods or load RF switching devices,thereby expanding the antenna's resonance and radiation characteristics,so that a single antenna can have the function of multiple antennas.Reconfigurable antennas can be divided into three categories: frequency reconfigurable,polarization reconfigurable,and pattern reconfigurable according to their functional classification.During the rapid development of wireless communication systems,they are also facing explosive growth in the number of users and increasingly scarce spectrum resources.Considering the reduction of spectrum congestion and the full use of spectrum resources,this requires the use of ultra-wideband(UWB)technology.With the FCC(Federal Communications Commission)in February 2002 stipulating a commercial range of 3.1-10.6GHz,UWB technology has been widely used.As the core of the wireless communication system,the UWB antenna is essential for the application of UWB technology.However,because the UWB communication system and other narrowband communication systems have overlapping operating frequency bands,such as the wireless local area network(WLAN)IEEE802.11 a frequency band(5.15-5.825GHz),Worldwide Interoperability for MicrowaveAccess(WiMAX)Frequency band(2.5-2.7GHz,3.3-3.7GHz),C-band(3.7-4.2GHz)for satellite communications,and the International Telecommunication Union frequency band ITU(7.9-8.45GHz),etc.,these narrowband communication systems will interfere with UWB communications.In order to reduce the mutual interference between frequency bands and improve the efficiency of spectrum utilization,the researches on UWB band-notched antennas are necessary.In this thesis,the characteristics of reconfigurable antennas,UWB antennas,and UWB band-notched antennas are synthesized,and the reconfigurable UWB band-notched antennas are studied.main tasks as follows:(1)In this thesis,the basic theory and implementation method of frequency reconfigurable technology is introduced firstly,and then the basic theory of UWB antenna is introduced in detail,Including the definition,classification,performance parameters of ultra-wideband antennas,and the implementation mesods of ultra-wideband bandwidth.In addition,several common methods for implementing notch-band are introduced.(2)A triple-band notch reconfigurable UWB antenna based on an ideal patch switch is simulated and designed.It has the advantages of good impedance matching,stable radiation,compact structure,and low manufacturing cost.In the antenna design,the ideal patch is used instead of the RF PIN diode switch.The antenna successfully avoids the interference of three narrowband signals on the ultra-wideband frequency band.(3)On the basis of a triple-band notch reconfigurable UWB antenna based on an ideal patch switch,the antenna structure was slightly adjusted.RF PIN diodes and bias circuits controlling the diode switch were placed on the antenna,To achieve discrete adjustment of the two notch bands WiMAX and WLAN.(4)A triple-band notch reconfigurable miniaturized UWB antenna based on PIN diode is proposed.In order to reduce the size of the antenna,three L-shaped slots are carved on the antenna radiation patch to realize the triple-band notch characteristics.In addition,RF PIN diode switch is placed on each slot and bias circuit which controls the diode switch is designed,thereby achieving reconfigurability between multiple modes of the antenna.All the antennas have been simulated in this thesis,and the last two antennas have alsobeen manufactured and measured.The simulated and measured results include S-parameter curves,patterns,and gains.It can be seen from the obtained results that the antenna designed in this thesis has good performance and is suitable for wireless communication systems. |
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