Research On Array Antennas For Vehicle Satellite Communication And Radar

With the rapid development of the vehicle industry,vehicles put forward higher requirements for wireless systems such as satellite communication,navigation and positioning,collision avoidance,etc.As a device for receiving and transmitting wireless signals,antenna plays an extremely important role in ensuring good performance of vehicle wireless systems.In this thesis,three kinds of array antennas for vehicle applications are designed to achieve low profile,high gain,broadband and wide beam width.The antennas consist of a circularly polarized array based on SIW cavity-backed dual-slot antenna elements,a planar conical beam array based on diverse ring elements,and a 77 GHz composite ridged waveguide slot array for vehicle millimeter-wave radar.In this thesis,the main research contents of these three kinds of arrays are summarized as follows:1)Research has made on array antennas based on SIW cavity-backed dual-slot antenna with dual-mode resonance.Firstly,a low-profile SIW cavity-backed dual-slot antenna with good performance of high gain and wide bandwidth is proposed and designed.By introducing dual-mode resonance,the antenna achieves a wide impedance bandwidth.Moreover,due to the dual-slot radiation excited in the same amplitude and phase,the antenna obtains high aperture efficiency and gain.The antenna has simple structure and low profile,and its overall size is0.76?₀×0.76?₀×0.037?₀.Measured results shows that the antenna achieves wide impedance bandwidth of 13.3%(5.2-5.94 GHz),high maximum gain of 8.3 d Bi,and high radiation efficiency,which prevails better overall performance among SIW cavity-backed slot antennas.4×4 linearly polarized and circular polarized arrays are designed and measured respectively,both of which are based on the identical array element of the SIW back-cavity double-slot antenna.Simulated and measured results show that both array antennas have good performance.The 4×4 circular polarized array achieves 3-d B axis ratio(AR)of 9.4%,and high gain of 17.1d Bi and gain fluctuation is about 0.2 d B in the 3-d B AR band,which is suitable for the application of vehicle satellite communication.2)A research has been made on a planar conical beam array antenna with diverse ring elements.Firstly,a basic annular plane inverted F antenna(APIFA)is proposed,which is a multi-feed annular structure formed by plane inverted F antenna rotating along the central axis.Conical beam pattern is produced by feeding the feeding points with the same amplitude and phase.Secondly,in order to reduce the number of feeding points of the APIFA and simplify the feeding network structure,the basic APIFA is improved to be a modified one with fewer feeding points.Then,three modified APIFAs with different radii are used as diverse array elements to form a coplanar concentric array,whose radiation pattern can be effectively controlled by adjusting the phase and amplitude of each diverse array element.Finally,a feeding network that can provide appropriate amplitudes and phases is designed and assembled to the bottom of the array radiator to form a complete planar conical beam array antenna,whose overall profile is only 0.11?₀.The measured results of the protype for the array antenna show that the its-10-d B impedance bandwidth of the antenna is 11.2%(4.71-5.27 GHz),the gain ranges 11.3-12.7d Bi within the impedance band,and the radiation patterns in the operating band are stable.The proposed planar conical beam array antenna can be used in vehicle satellite navigation and positioning system.3)In order to meet the application requirements of vehicle millimeter-wave radar,two kinds of composite ridge waveguide slot array antennas working at frequency of 77 GHz are studied.One adopts edge feeding scheme and the other adopts center feeding scheme.The radiation slots of the edge feeding array antenna achieve collinear arrangement by controlling the lower ridge structure of the array antenna with edge feeding structure,so that the antenna obtain symmetry and low cross polarization radiation pattern in transverse plane.The proposed edge-fed array antenna has high gain and radiation efficiency,but its bandwidth is narrow and cannot cover the band of 76-81 GHz completely,and the beam direction will be deflected with as frequency changes.Compared with the edge feeding array antenna,the radiation slots of the center feeding array antenna are staggered.The corporate feeing antenna has advantages of wide impedance bandwidth,stable beam direction and low sidelobe.By cutting slots between the array elements on the outer surface of the metal ridged waveguide to change the surface current distribution,the E-plane beam width of the antenna is widened within the operating frequency of 76–81 GHz.Samples of single-array and three-array antennas are fabricated and tested.