Design Of Wideband Antenna For Modern Communication

With the development of communication technologies and the popularization of mobile communication terminals,the number of antennas in mobile terminals is increasing,which limits the miniaturization and upgrade of the terminal.With the construction and development of IOTs and smart cities,key devices such as sensors will be widely distributed,and such devices will face challenges such as battery life and battery replacement.RF energy harvesting technology can use an antenna to harvest RF energy in the environment to power low-power devices such as sensors,but the radio frequency spectrum in the environment is more dispersed.It is foreseeable that in order to adapt to modern communication environments and technologies,the working bandwidth of the antenna will become wider and wider,and it will eventually develop into an ultra-wideband antenna.The most representative Wideband antenna is the UWB antenna that has been greatly developed since the UWB band was opened to civilian use in 2002 by the Federal Communications Commission and the SWB antenna with impedance bandwidth ratio greater than 10:1.However,the FCC limits the radiated power of the UWB antenna strictly below-41.3 dBm/MHz.Such a low radiated power will cause the signal transmitted by the UWB antenna to have a relatively large attenuation in a multi-path environment.For the SWB antenna,it is necessary to make its bandwidth ratio greater than 10:1,which has a large design difficulty.Therefore,this paper presents two innovative Wideband antenna designs.The first is a compact UWB-MIMO antenna system.Multi-Input Multiple-Output(MIMO)technology considers multipath as a favorable factor to solve the problem of energy fading,which makes the UWB antenna more practical.what's more,we use polarization diversity technology and a pair of inverted L-shaped decoupling stubs and an inverted Z-shaped decoupling stubs to increase isolation between antenna elements.The second is a miniaturized SWB antenna.The elliptic function curve and the exponential function curve are applied to the antenna design to make the edge structure of the antenna smoother without mutation and feed it with the coplanar waveguide.Finally,the SWB antenna has a bandwidth ratio much larger than 50:1.This thesis mainly elaborates from the following aspects:First,it introduces the research background and significance of UWB antennas and the research status at home and abroad;secondly,it introduces the basic theory of the microstrip antenna and basic performance parameters of the antenna;thirdly,two UWB antenna systems were designed,produced,analyzed and discussed.Fourthly,we summarize and prospect the UWB.antenna system design.