Research And Design Of Low Profile Wideband Patch Antenna

Antennas are the basic components of wireless communication systems.With the development of communication technology and the increasingly scarce spectrum resources of wireless communication systems,the actual demand for antenna performance is also increasing.Patch antenna is widely used due to its light weight,low profile,low cost,easy manufacturing and easy conformation with the carrier.At the same time,the working environment faced by modern communication systems is becoming more and more complex.Compared with linearly polarized antennas,circular polarization antennas have the advantages of receiving/transmitting electromagnetic waves of different polarizations,strong anti-interference ability,little influence by Faraday effect,etc.,which can be applied in a wider range of scenarios and ensure the smooth flow of real-time communication.In this paper,aiming at the problem of narrow working frequency band of traditional microstrip patch antenna,we analyze the working modes of low profile broadband patch antenna based on multimode resonance theory,and design the multimode resonant broadband patch antenna under the condition of low profile;we also design a low profile broadband circularly polarized metasurface antenna.The main work of this paper is as follows:1.A low-profile dual-mode resonant wideband patch antenna operating in TM_1/2,0 and TM_1/2,2modes is designed.The designed antenna uses rectangular PIFA instead of the traditional microstrip patch antenna to suppress redundant modes;shorting pins are loaded under the radiation patch to significantly increase the resonance frequency of TM_1/2,0 mode(f_1/2,0)without affecting the resonant frequency of the TM_1/2,2 mode(f_1/2,2);secondly,a pair of parallel slots are etched on the patch to reduce f_1/2,2 without changing the lower frequency f_1/2,0,and finally the width of the patch is gradually increased to make f_1/2,2 drop faster,make f_1/2,2 closer to f_1/2,0,and finally the dual radiation resonance modes can merge with each other to achieve a bandwidth enhancement.The IBW of antenna is 1.57-1.74GHz(10.3%),and the thickness is only 4.5mm(0.025?₀).In addition,a cylindrical conformal patch antenna is designed based on the principle of dual-mode resonance.Similar operation excites the dual-resonance mode,and the bandwidth can be expanded to 9.1%when the thickness of the antenna is only 3.5mm(0.019?₀).2.A multimode resonant low profile broadband patch antenna with improved radiation performance is designed.By loading several shorting walls,the redundant mode is suppressed,the sidelobe of E-plane is reduced and the cross polarization of H-plane is reduced;loading shorting pins increases the resonant frequency of TM_1/2,0 mode;a rectangular slot is etched at the zero current position of the TM_3/2,0 mode to excite the resonant slot mode TM_RS,making the two modes gradually approach to the TM_3/2,0 modes,achieving three-mode resonance to increase the bandwidth,and the antenna thickness is only 3mm(0.029?₀).The impedance bandwidth of|S₁₁|<-10d B is increased to 18%(2.64–3.17 GHz);In addition,expanded research has been carried out on the basis of the tri-mode wideband antenna,further increasing the width of the patch,and reasonably adjust the parameters of the shorting pins and the resonant slot,and keep the original three mode frequencies unchanged,so that the higher frequency of TM_1/2,2 mode is reduced,and finally four-mode resonance is realized.The antenna height keeps 3mm unchanged,and the bandwidth further increases to 21.7%(2.67-3.32GHz).The radiation performance of both antennas is greatly improved,and the cross polarization of H-plane is reduced to less than-20d B.3.A low-profile broadband circularly polarized metasurface antenna is designed.On the basis of Wilkinson power divider,a quarter wavelength feed circuit path difference is added,and a 90°phase difference is provided for feeding the square patch to achieve circularly polarized radiation;The working bandwidth and gain of the circularly polarized patch are improved by loading a square ring metaurface,and the overall thickness of the low profile circularly polarized antenna is 6 mm(0.05?₀),the bandwidth of|S₁₁|<-10d B is 36.7%(2.0–2.9 GHz),and the 3-d B axial ratio bandwidth is 26.1%(2.0-2.6 GHz).