| Ultra-wideband(UWB)wide-angle covering array antennas are widely used in the civilian and military fields.In order to overcome the shortcomings of traditional electric scanning arrays,such as large scale,long scanning periods and short beam-standing time,this paper mainly studies the UWB wide-angle coverage technologies of small array antennas,including UWB wide-beam antenna technology and UWB array antenna technology.This paper mainly completed the following tasks:Firstly,based on the basic principle of UWB matching,a gradient balun with an impedance bandwidth of more than 9 times is designed;a broadband branch phase shifter is designed using a microstrip coplanar waveguide transmission line.Simulation shows that,compared with Phase shifter designed with traditional microstrip lines,phase shifter designed with microstrip coplanar waveguide transmission lines has more stable amplitude output characteristics in compact space;slot balun has been studied and designed,and its bandwidth exceeds twice the frequency compared to broadband branch phase shifter with wider impedance bandwidth and more stable output characteristics.Secondly,the basic characteristics of conical spiral antennas are studied,and the effects of pitch and inclination on antenna performance are summarized.Based on this,a wide-beam circularly polarized antenna that works in the SC/X band is designed;Aiming at the problem of narrow pattern bandwidth and unstable beam of traditional conical spiral antenna,a method of comprehensively using variable pitch and variable cone angle is proposed to realize the stable wide-beam radiation of 2~18GHz and reduce the antenna height by 23%;The technology of circularly polarized beam with unequal beamwidth on the elevation and azimuth plane is studied.Based on this technology,the design of the SC/X band common aperture planar elliptical spiral antenna is proposed,which achieves stable radiation characteristics of a wide beam on the elevation plane and a narrow beam on the azimuth plane in a frequency range of more than twice the frequency.After simulation and testing,the above wide-band wide-beam technology is feasible.Finally,a wide-beam conical spiral antenna is used as the array element,and a 6-element circular array working in the SC/X band is designed.The conditions for using a single wide beam to achieve wide-angle coverage are analyzed.Phase compensation technology and approximate independent-frequency technology of array factor are studied and used respectively,which makes the designed SC/X band array antenna achieve a gain coverage of more than 5d Bic with only one wide beam in the airspace of 5° ~ 65° on the elevation plane.The approximate independent-frequency technology of array factor proposed in this paper can be effectively applied to UWB wide-angle covering array antennas by simulation analysis.The array antenna prototype is tested at the end of the article,and the measurement results and data analysis are given. |
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