Research And Design Of Ultrawideband Antenna For Smart Skin

As an advanced technology,smart skin can bend the device into various shapes or even be embedded into the surface of the carrier as skin,which is conducive to the aerodynamic integration and stealth design of aircraft.Smart skin has extremely high requirements on the RF antenna level,which requires the antenna to be miniaturized,low profile and easy to conform.With the continuous development of ultra-wideband(UWB)technology,smart skin has put forward the requirement of UWB.Therefore,it is of great significance to research the UWB smart skin antenna system,which has gradually become a trend in the future.However,at present,the research on UWB smart skin antenna is relatively few,with few substantive contents and references.To research the UWB smart skin,the primary solution is to seek the UWB antenna configuration suitable for the skin structure.In this paper,three kinds of available UWB antennas with low profile are studied,which are designed from five aspects: antenna miniaturization,notch characteristics,circular polarization characteristics,conformal characteristics and multiple input multiple output(MIMO).The antennas were fabricated and their performances were tested.The correctness of the design were verified.Finally,the array characteristics were studied.The main content and innovations are as follows:1.Miniaturization,notch,conformal and MIMO studies of new planar UWB antennas.Aiming at the large size of planar UWB antenna,a miniaturized UWB monopole antenna with fractal structure is designed.The antenna still has a very wide impedance bandwidth in the case of small size,reaching dozens of GHz,and the bandwidth can remain stable under cylindrical conformal condition.In order to solve the narrowband interference problem in UWB working band,a quintuple band-notched UWB antenna is designed,and all the notched peeks of voltage standing wave ratio(VSWR)exceed 9.Aiming at the complex design of MIMO antenna decoupling structure,a simple dual-port polarization diversity MIMO slot UWB antenna is studied.It can achieve low mutual coupling without decoupling structure and has certain innovation.The first attempt was made to combine the Vivaldi antenna and UWB slot antenna,and a miniaturized angle diversity UWB MIMO antenna was proposed by taking advantage of the radiation pattern difference between different antennas.It has lower mutual coupling and the working frequency can be extended to the lower end.2.Study on circular polarization characteristics of planar UWB antennas.Aiming at the narrow axial ratio(AR)bandwidth of traditional microstrip antenna,a design method of broadband circularly polarized antenna based on UWB planar antenna is studied.A C-shaped UWB monopole antenna with broadband AR is proposed.The AR bandwidth of the antenna exceeds 7 GHz,which is not only superiorto other circular polarization schemes,but also adjusting the C-shaped structure,the impedance bandwidth and AR bandwidth are relatively stable with high redundancy in design.A coplanar waveguide(CPW)-fed UWB circularly polarized slot antenna is designed,which has the advantages of small size,simple structure and broad AR bandwidth ranging from 3.1 to 7.3GHz.It has certain reference significance for the research of broadband circularly polarized slot antenna.The traditional circularly polarized antenna can only work in one mode,using two-port MIMO design scheme,a broadband dual circularly polarized MIMO antenna which can work in two different circularly polarized modes is proposed.It not only has 1.9?5.9 GHz AR bandwidth and1.9?14.3 GHz impedance bandwidth,but also has relatively small mutual coupling.3.Miniaturization,notch,and conformal studies of log-periodic dipole array(LPDA)antennas.Aiming at the problem that the array size is large when the LPDA antenna works at low frequency,a scheme is studied and realized that the array terminal is loaded with T-shaped structure to reduce the antenna size,working frequency and obtain miniaturization.Aiming at the narrowband interference problem of LPDA antenna in the UWB working frequency band,a planar and conformal dual band-notched LPDA antenna with remarkable effect was made by opening slot in the parallel double-line.Aiming at the narrow impedance bandwidth of the antenna,the structure of parallel double-line is improved and the impedance bandwidth was greatly expanded.On the basis of the above,the characteristics of the LPDA antenna under different cylindrical conformal conditions are studied.The results show that the corresponding indicators are good and stable,and are less affected by conformal change.4.Miniaturization,notch,conformal and MIMO studies of tapered slot UWB antennas.Aiming at the large size of the traditional tapered slot antenna,this paper uses the impedance transformation principle of the microstrip feeder to design and implement a miniaturized Vivaldi antenna with microstrip side feeding is designed and realized by using the impedance transformation principle of the microstrip line,and its dual notched characteristics is studied.The measured results show that the radiating and notched characteristics of the antenna have reached the design expectation,and the design method is novel.A compact CPW-fed dual band-notched tapered slot antenna with E-shaped and L-shaped slits is studied,and a triple band-notched UWB Vivaldi antenna is designed.The combination design method of miniaturized dual port MIMO Vivaldi antenna is proposed,and the feasibility of achieving dual notch and low mutual coupling is studied.Similarly,a conformal dual band-notched MIMO stepped slot antenna is realized,and the measured results show that it has wider working bandwidth in a smaller size,and can still maintain broadband,notch and radiation characteristics under conformal conditions.5.Based on the UWB single antenna,the characteristics of planar and conformal UWB array antennas are studied.Firstly,the planar UWB array antenna is studied by using the quintuple band-notched antenna element structure.The gain of the array antenna meets the expectation and has certain beam scanning characteristics.Secondly,the planar and conformal LPDA antenna are studied.The working bandwidth of the antenna is less affected by the mutual coupling.In the UWB working frequency band,both planar and conformal conditions,the array antennas are prone to generate grating lobes at high frequencies,but they have strong end-fire characteristics at low frequencies.This paper focuses on the research of Vivaldi antenna array.Based on the extremely narrow longitudinal size of Vivaldi antenna that has been successfully realized as the array element,the array antenna not only has broad bandwidth and wide Angle scanning characteristics,but also has a very low profile.Accordingly,the method of loading reflection surface to reduce the back lobe is studied,which is worthy of further study.Finally,the cylindrical conformal UWB MIMO array antenna is studied by using the MIMO stepped slot antenna as the array antenna unit.The conformal array has very wide working bandwidth and can achieve strong end-fire characteristics in the broadband range.At the same time,the array antenna also has very good filtering characteristics.By changing the working state of the MIMO antenna ports,the forward and backward switching of the end-fire direction can be achieved,which has great application value.In this dissertation,some new design ideas and concepts are applied to the research of UWB antenna,and some good research results have been achieved,which has a certain reference value for the future engineering realization of UWB smart skin.