Research And Design Of Ultra Wideband Low Profile Antenna

With the development of information technology,especially radio electr onics and electromagnetics,the demand for miniaturization,integration and functional diversification of wireless communication equipment is increasing.As an indispensable tool of electromagnetic transcei ver,UWB(Ultra-wideband)low profile antenna has been paid more and more attention by researchers of microwave engineering.In this paper,the research and design of UWB low profile antenna in frequency domain and time domain are carried out to solve the problem of high fidelity radiation of pulse signal waveform.The main work of this paper is as follows:1.A design method of microwave substrate with controllable permittivity is proposed.On this basis,a six octave ultra wideband planar antenna is desig ned.Aiming at the problem of narrow frequency band of microstrip patch antenna,starting from the idea of metamaterial electromagnetic manipulation,an ultra wideband antenna with return loss S11 less than-10 d B from 4.19GHz?24.90 GHz is realized by etching the snowflake like element structure to change the inductance and capacitance of rectangular radiation patch.Meanwhile,grooving the ground plate to introduce multi resonance technology.Next,aiming at the miniaturization design of the antenna,based on the periodic waveguide theory,the photonic crystal is creatively applied to the dielectric substrate design of the microstrip antenna,which changes the gain reduction problem caused by the appearance of high-order modes and the increase of dielectric loss when the traditional microstrip antenna is miniaturized by increasing the thickness of the dielectric substrate,and realizes the dielectric constant controllable design Substrate.Due to the electromagnetic band gap function of photonic crystal structure,the novel microstrip antenna loaded with two-dimensional photonic crystal dielectric substrate will not reduce the antenna gain while increasing the thickness of the substrate.The proposed two-dimensional photonic crystal special permittivity substrate has important application value for the miniaturization design of microstrip antenna.2.A low frequency ultra wideband low profile antenna with ridge and dielectric is designed based on the structure of TEM(Transverse electromagnetic mode)horn antenna.Inspired by fishtail structure and classical ridge structure,an exponential ridged and dielectric TEM horn broadband antenna with S11 less than-10 d B between65MHz?308MHz is designed through the unique bending structure design and combining with the dielectric loading technology.On the one hand,The low frequency of the antenna is expanded.On the other hand,the stronger directivity and wider frequency range are realized.3.A miniaturized ultra short wave band flat funnel antenna is designed based on the structure of biconical antenna.Because the radiation pattern of biconical antenna presents apple shape and has radiation zero,The funnel-shaped antenna can effectively solve the blind spot problem when the antenna equipment establishes communication with air equipment through the pattern shaping design.Furthermore,the reflection coefficient of the designed an tenna is reduced by the nonreflecting resistor loading technology.Designing a low profile directional radiation Very high frequency funnel antenna with VSWR less than 3 from 30 MHz to 300 MHz.The experimental results show that the antenna has a high fidelity for the radiation of time domain pulse signal.