Research On Low-profile And Wide-angle Scanning Phased Array

Phased array antenna has the characteristics of high gain and beam scanning,so it is widely used in communication systems such as phased array radar,wireless communication.The phased array antenna with low profile and wide angle scanning characteristics has a broad application prospect,which is also a problem in the field of phased array.In this thesis,the impedance and scanning characteristics of low profile phased array are researched,through the analysis of mirror principle and realized gain,and the design of wide angle low profile phased array with stable scanning gain is proposed.The main contents are as follows:1.By studying the realizable gain of phased array,,a method is proposed to construct a saddle-shaped active element pattern with a saddle in the center of the side shooting direction to reduce the gain fluctuation during beam scanning,combined with the pattern product theorem.2.An E-plane wide-angle scanning phased array antenna based on equivalent magnetic current element is proposed.The radiation patch of the antenna is connected to the ground through a dense of metallized via,which realizes the basic working mode of the equivalent magnetic current element,so that the array element has the characteristic of E-plane wide beam.By forming a ten-element phased array uniformly arranged along the E plane,the wide-angle scanning ability of this low-profile phased array is proved.The influence of mutual coupling on beam scanning characteristics is studied by analyzing the parameters such as active standing wave and active element pattern.3.A low profile dipole phased array antenna with special beam shape is proposed.Firstly,by studying the radiation characteristics of the electric dipole antenna,it shows that the H plane pattern of the electric dipole antenna has the characteristics of wide beam and saddle-shaped with controllable sag depth under a certain profile,so the electric dipole is used as the basic element of the H plane linear array.After that,the height of the section is reduced by using the artificial magnetic conductor structure,and the pattern of the E plane is broadened while keeping the characteristics of the H plane pattern.Then the mutual impedance of the adjacent elements is reduced by the decoupling structure,so that the transmission coefficient between the adjacent elements in the working frequency band is lower than-23 dB.Then,in order to solve the problem of balanced feeding,an electric dipole with a new type of planar balun is proposed considering the idea of coplanar waveguide.By analyzing the relationship between the beam scanning characteristics and the saddle-shaped active element pattern and the number of array elements,it shows that the saddle-shaped pattern is beneficial to the gain stability of beam scanning,the adjustment of the sag depth of the element pattern and reduce the gain fluctuation of the desired scanning range.Finally,a 1 × 10 H-plane array is proposed and tested.Measured and simulated results show that when the antenna profile is only 7.5mm,the beam scanning angles of 3.5GHz and 3.6GHz relative to the maximum principal polarization gain decrease to ±87 degrees and ±92 degrees,respectively,and the active reflection coefficients of each element are less than-10 dB at all given scanning angles.The proposed phased array antenna has the characteristics of low profile,wide angle scanning,wide angle matching,stable gain and feed balance.