Vivaldi Antennas And Their Engineering Design

With the development of 5G technology,emerging technologies such as artificial intelligence,unmanned driving,and VR continue to emerge,and more demands are placed on communication systems,it requires wider bandwidth,greater system capacity,and higher speed transmission rates.Driven by this demand,UWB antennas have received widespread attention.As an important representative of the ultra-wideband antenna,the Vivaldi antenna has become a research hotspot because of its ultra-wide bandwidth,stable gain,and good directivity.The main research contents of this thesis include the common aperture dual frequency Vivaldi antenna,dual slots dual polarization Vivaldi and millimeter wave high gain Vivaldi.Broadband dual-band common-caliber Vivaldi antenna design.A dual-frequency Vivaldi antenna that works on microwave and millimeter waves is designed by loading an exponentially graded slot line at the aperture of a traditional Vivaldi antenna.The function of the exponential gradient slot line has two aspects: firstly,It can be used to increase the gain of traditional Vivaldi at low frequencies.Secondly,It can radiate as an antenna at high frequencies.At the same time,the influence of the width,length and slot spacing of the exponentially tapered slot line structure is studied.The results show that the width of the exponential gradient groove line mainly affects the high frequency,and the length mainly affects the low frequency,that is,its high and low frequencies can be adjusted independently,so this antenna form can be applied to any combination of high and low frequency bands.Dual-slot dual-polarized Vivaldi antenna design.The content includes: firstly,In order to solve the problem of low gain and poor directivity of the traditional Vivaldi antenna unit,a dual slot Vivaldi with a tapered slit in the radiating arm is designed as a dual-polarized antenna unit.Compared with the traditional Vivaldi,the gain is increased by 1.5-2d B,and it has better directionality.The dual-polarized antenna is generated by crossing two dual-slot Vivaldi antenna elements.Because the feeding structure of the cross section does not pass through the microstrip line to the slot line,the engineering complexity is lower than that of the traditional dual-polarized Vivaldi.Secondl,In order to further improve the isolation of dual-polarized Vivaldi,the two dual-slot Vivaldi antenna elements are placed in a T-shaped structure to generate dual polarization.The isolation is greatly improved compared to the cross-shaped dual polarization.In the end,the isolation in the 3-9GHz band reaches-37.5d B,and the isolation is improved by 10.5d B compared with the cross-type dual-polarized antenna.Millimeter wave high gain Vivaldi antenna.In order to solve the problem that the gain of the Vivaldi antenna working in the millimeter wave band is generally low,a high-gain Vivaldi antenna working at 65-85 GHz is designed.Firstly,In view of the shortcomings of the traditional microstrip feed with high loss at high frequency,the substrate integrated waveguide to coplanar waveguide feed is used.Compared with the traditional feed,this form of feed has a loss reduction of an order of magnitude.Secondly,by extending the traditional Vivaldi radiation arms and grooving the edges of the radiation arms on both sides of the antenna,the current path is extended to make the current more concentrated on the inner edge,thereby improving the matching characteristics and increasing the gain.Thirdly,by adding a director structure at the front end of the dielectric substrate,the phase difference problem at the caliber surface is solved.Fourthly,by introducing a dielectric cavity around the dielectric substrate,the problem surface wave effect of the antenna is solved,and the gain is further improved.Eventually,the gain stabilized at around 19 d B in the 65-85 GHz band,compared with the reference antenna,the gain increased by 13 d B...