Research On Leaky Wave Antenna And Array Antenna Based On Gap Waveguide Technology

Gap waveguide(GW)is a novel guided wave structure with mixed boundary conditions,by virtue of characteristics such as high-efficiency,wideband,easy-fabrication and global-mode suppression,it has a wide application prospect in the fields of antenna,filter,diplexer and so on.This paper mainly focuses on the researches of leaky wave antenna(LWA)and array antenna in gap waveguide technology.In view of the common gap waveguide antenna having high sidelobes,a new linear tapered structure of the antenna and one based on Taylor line source method are proposed to reduce the high sidelobes.Periodic loading of unit cell of the LWA leads to a high directivity,the impedance matching technique of the unit cell is employed to design a novel ridge gap waveguide LWA with the characteristic of seamless scanning,thus,the open-stopband(OSB)effect is eliminated.Since gain varies evidently when the main beam of antenna scans together with the OSB effect,combined methods referring to as loading magneto-electric antenna layer and impedance matching technique of the unit cell of the antenna are used to design a novel seamless scanning LWA.Due to the fact that the existing GW antennas are mostly linearly polarized,a novel aperture coupled circularly polarized array antenna in RGW technology is proposed.A novel high-efficiency wideband array antenna combining with GW technology,back cavity antenna technology and magneto-electric dipole antenna technology is proposed because of the hurdle associating with high-efficiency and wideband in the design of array antenna in the millimeter wave band.The details are as follows:1.A novel linear tapered groove gap waveguide LWA is proposed.The antenna operates in the X-band,by changing the heights of the pins locating on the non-radiating side,the attenuation constant will be optimized.Then,the proposed antenna is fabricated and measured.Measurements show that the sidelobes are reduced by 3d B compared with uniform structure.Next,based on Taylor line source method,a low sidelobe GGW LWA operating in the Ku-band is proposed.The radiation patterns of the antenna are improved by adding corrugated slots on the upper and lower plates of the waveguide and introducing cuts in the feed flanges.Eventually,the sidelobe of the radiation pattern at the center frequency is suppressed below-20 dB.2.A novel RGW LWA is proposed,the impedance matching technique of the unit cell is utilized to reduce the impact arising from the OSB effect.Then,the proposed antenna is fabricated and measured.Measurements demonstrate that the seamless scanning range is from-9 degree to +19 degree.Moreover,the proposed multi stepped impedance transform possesses wide applicable frequency band,which covers the whole Ku-band.The performance is better than those in the literature.3.A novel seamless scanning GGW LWA is proposed.Loading of a ME dipole layer improved the gain flatness effectively,the gain variation is less than 2.7d B in the wideband frequency;the impedance matching of the unit cell antenna is also utilized to support a seamless scanning across the operating band.The scanning range is 24 degree,and the average gain is 15.78 dB.4.A novel aperture coupled circularly polarized array antenna is proposed.By introducing L-shaped slot coupling to an oval shaped patch,circularly polarized radiation characteristic is achieved.The impedance bandwidth of the antenna is from 14.12 GHz to 15.37 GHz,and 1dB axial ratio bandwidth is between 14.73 GHz and 15.15 GHz.The proposed novel antenna will be a good guidance for circularly polarized gap waveguide array antenna.5.A novel high-efficiency wideband array antenna in the millimeter wave band is proposed.The proposed antenna makes use of GW technology,the back-cavity antenna and the ME dipole antenna technology to achieve the high-efficiency and wideband characteristics.The impedance bandwidth of the array antenna is 56.5GHz-65.5GHz,the relative bandwidth is 15%.The aperture efficiency of the antenna is more than 90% in the whole frequency band,the average gain is 26.4dB,and the gain variation is less than 1.6dB.Taking the aperture efficiency and the bandwidth into consideration,the proposed antenna has better performances than those in the literature.