| Microstrip planar array antennas are of significant interest to researchers in the fields of satellite communication,deep space exploration,and radar remote sensing owing to their attractive features such as low profile,light weight,easy integration,and low cost.However,the conventional microstrip planar array antenna exhibits narrow-band characteristics,which limit its application.To overcome this limitation,this paper proposes the use of a fractal structure in the design of a microstrip planar array antenna element.The proposed design employs the spatial filling and self-similarity of fractal structure,leading to a significant reduction in the size of the element and an expansion of the antenna bandwidth.The proposed antenna utilizes a parallel feed network,and the feed network and radiation unit incorporate a double-layer structure,enhancing the flexibility of the design.The main research contents of this paper include the following parts :(1)Research on high gain slot array antenna based on Koch snowflake fractal structureThe radiation slot unit cell is designed using the Koch snowflake fractal,and arrays are designed and tested,exhibiting high directional performance.The proposed antenna array exhibits a 3-d B gain bandwidth of 18.40%(5.13-6.20 GHz).At the operating frequency of 5.8 GHz,the antenna gain reaches up to 20.06 d Bi,with an aperture efficiency of 80.69%.(2)Research on low mutual coupling and high gain array antenna loaded with COS coupled resonatorsThe radiation patch element is designed using the Koch snowflake fractal,and the array is employed.A COS coupling resonator is added around the radiation patch to reduce the mutual coupling between adjacent units.The proposed structure consists of two COS curves etched on both sides of the dielectric substrate,with the middle being connected by a metal via.The measured results reveal an impedance bandwidth of 9.83%(5.54-6.11 GHz),a 3-d B gain bandwidth of 23.93%(5.00-6.39 GHz),and an impedance bandwidth that is 3.31% higher than that of the reference antenna without the COS coupling resonator.At 5.8 GHz,the antenna gain is 20.46 d Bi,demonstrating good low mutual coupling and high gain performance. |
