Research Of Wideband And High-Gain End-Fire Antenna Based On Electromagnetic Manipulation By Metasurface

Electromagnetic wave propagates along the direction of the antenna structure is called by end-fire antenna.The radiated electromagnetic wave of the end-fire antenna is consistent with the direction of the antenna structure,and has the advantages of high gain,small size and low profile,so the end-fire antenna is suitable for low wind resistance or high-speed mobile carrier,such as aircraft,unmanned aerial vehicle,missile,etc.At the same time,with the gradual improvement of the using frequency of modern communication system,the demand for miniaturization of end-fire antenna size is also gradually increasing.However,the miniaturization design of the antenna is often at the expense of the bandwidth and gain of the antenna.Therefore,with the process of miniaturization for end-fire antenna,it is very meaningful in how to maintain the working bandwidth and gain of the antenna.In this thesis,two types of end-fire antenna are designed based on the characteristics of metasurface about impedance modulation and effective refractive index:1.A low-profile end-fire antenna is designed based on the impedance modulation characteristics of the metasurface,placing in the extending direction of aperture surface of H-plane horn antenna as the source of surface wave.Because the surface impedance of the grounded dielectric can be modulated by the metasurface,the surface wave breaks away from the bondage of the grounded dielectric,in the metasurface coverage area,it can be converted into a space electromagnetic wave to achieve the radiation of the endfire antenna.The measured results show that the bandwidth of the antenna is 3.8-16.7GHz,and gain in the working frequency band is 8.6-16.67 d Bi.2.A high-gain printed log-period dipole antenna is designed based on the metasurface which is charactered by the effective refractive index.With the bandwidth of 3-10.6 GHz and the gain of 5.1-8.1 d Bi,The antenna is designed according to the design method of the microstrip log-period antenna.In order to improve the gain,the metasurface is placed in the near-field area of the antenna to control the amplitude and phase of the electromagnetic field,in which the uniform refractive index metasurface is loaded near microstrip log periodic antenna to increase the radiation electric field in the end-fire direction,and the gradient refractive index metasurface is loaded in the end-fire direction of the antenna to focus the electromagnetic wave.In this way,the gain of PLPDA is increased by 1.1-4.1 d Bi in its working bandwidth.Finally,multiple-input multiple-output(MIMO)antenna array is constructed by a high-gain printed log-period dipole antenna to improve communication system capacity and link quality.