| The modern war is fundamentally an electromagnetic war.All kinds of land mobile platforms,ships and fighters need all kinds of frequency band antennas to meet the requirements of different communication,perception,tracking and guidance.In space limited carriers,multi-type and broadband electromagnetic signal conversion devices,such as antennas,coupling between them and other interactions lead to serious electromagnetic compatibility issues.On the other hand,in modern times,it will be destroyed as long as it is found,the stealth and anti-stealth capabilities of the equipment become more and more important.P-band radios located in the UHF band were commonly used in anti-stealth radar,but antennas in this band have large size,its own radar cross section（RCS）value is large while detecting the stealthy target.To improve the survivability of the equipment,it is urgent to solve the stealthy problem of the antenna in the UHF band and even longer in the VHF band.Reasonable regulation of the time-sharing concentration of plasma and fusion a variety of VHF-UHF band antenna through the reconstruction technology,to enhance the electromagnetic compatibility of the integrated system and reduce the synthetic antenna RCS,which is the focus of current research on military powers.In this thesis,the low RCS stealth theory of plasma antenna is studied,and the principle solution of the above problem is given.In the lower frequency range,the geometric size of the antenna is large,but the corresponding plasma concentration needs to be low.When the electromagnetic wave frequency of the detection radar is higher than the current plasma frequency,the plasma antenna shows a good stealth performance;In the higher frequency,the plasma concentration is larger,but the antenna size is smaller.whether it is metal antenna or plasma antenna,the RCS value of the antenna will be greatly reduced compared with the associated low frequency antenna.The simulation results show that the reconfigurable plasma VHF-UHF antenna based on this principle can achieve the goal of backward RCS lower 10dBsm than metal antenna in the210GHz monitoring radar band,which can meet the demand from stealth combat.Technically,this thesis analyzes in different frequency bands,first analyzes the monostatic RCS of monopole antennas when they are made of metal and different thickness of quartz tube.The evolution of low RCS stealth performance of plasma antenna is given,and the direction is pointed out for the development of the follow-up technology and the engineering practice.Considering the requirements of users for the antenna index,taking into account the electromagnetic compatibility of the radar antenna in a limited carrier space,two miniaturized broadband antennas are designed through the reconfigurable way and not changing the physical structure basically.The first is a plasma antenna based on a monopole antenna with parasitic elements,which operates in the 40100MHz and 100300MHz of the VHF band.In the operating band,satisfied the S11<-10dB and other antenna indicators,through top capacitance loaded technology to achieve the miniaturization of the antenna.Second,a"3T"structure antenna is proposed based on the impedance step-by-step and tandem branch theory.Analysis results show that the designed VHF-UHF reconfigurable plasma antenna satisfies the S11<-6dB in the frequency of 40120MHz and120500MHz,and antenna radiation pattern is omnidirectional in the H plane,gain is greater than 1dB.After optimizing the floor,the working frequency of the full plasma antenna is 30100MHz and 100512MHz,and satisfied the requirement of backward RCS is 10dBsm lower than the same metal antenna in the 210GHz radar band and other requirements.A 1:4 ratio plasma antenna based on monopole with parasitic elements in frequency of 40100MHz was fabricated.In addition,a 1:10"3T"shrink-ratio metal antenna was fabricated and processed.The test results were in good agreement with the simulation results.In summary,through the research and application of plasma and based on the design and analysis of two VHF-UHF broadband plasmas antenna,the potential solutions to the technical problem of multi-antenna fusion and stealth are given in this thesis.Believe that the relevant theory and engineering practice in-depth development,will certainly promote the development and application of high-performance antenna technology in the limited space. |
