Split-ring resonator loaded slot array

The slotted waveguide antenna stiffened structure utilizes conventional hat-stiffeners or blade stiffeners in aircraft sandwich structures as microwave waveguides. By machining slots through the outer skin and into the waveguide, large slotted waveguide antenna arrays may be integrated into the aircraft structure. However, the slot length is typically resonant with half-wavelength spacing thereby degrading the load-bearing capacity of the structure. This paper demonstrates a method to achieve comparable gain from sub-resonant slotted waveguide antenna array by loading each slot with a split-ring resonator. The structural properties of the hat-stiffened panel may then be restored.