A novel sandwich structured spoof surface plasmon polaritons antenna integrating multibeam and enhanced mechanical performances

The conventional antennas will increase the radar cross section of aircrafts and affect their aerodynamic performances, a novel antenna scheme for radiation and load-bearing integrated design based on composite sandwich structure is proposed. By constructing spoof surface plasmon polaritons (SSPPs) structure and combining it with glass fiber composite (FR-4) plates, the radiation direction of the monopole can be controlled and the antenna will be endowed with load-bearing capacity. At the meantime, polymethacrylimide (PMI) foam is filled in its spacing to improve the mechanical performances greatly. Through electromagnetic (EM) simulation and test, it is found that four-beam radiation in different directions and eight-beam radiation can be realized by changing the position of the FR-4 laminates, and the bandwidth is all about 1 GHz with a peak gain about 6.5 dBi. Out-of-plane compression experiment indicates that the proposed PMI foam-filled multibeam antenna structure (PFMAS) gathers the high load-bearing capacity of multibeam antenna structure (MAS) and the high energy absorption characteristics of PMI foam, showing an obvious coupling effect. Its specific compressive strength is 150.10 % and 6.28 %, and energy absorption capacity per unit volume is 169.91 % and 362.08 % higher than that of PMI foam and MAS, respectively. The proposed PFMAS improves the structural utilization efficiency, and can be applied to some interlocking units of square honeycomb structure to endow multibeam radiation characteristics, which can expand the application of integrated antenna structures effectively.