Application of EBG structures at sub-array level

Low efficiency and pattern degradation are specific problems encountered in phased-array designs based on integrated technology, as for example used in low-profile radar applications. These problems are largely due to the excitation of surface waves (SW). It was demonstrated in earlier work that Electromagnetic Band Gap (EBG) technology can decrease or even eliminate SWs. However, for the most effective application, the EBG should preferably fully enclose the individual elements that compose the array. This inherently creates a problem of spacing, in the sense that scanning becomes more limited or virtually impossible. A solution to the problem could be found in the application of the EBG at sub-array level. In this contribution we investigate the effect of this concept in terms of directivity, radiation-pattern purity and scattering parameters. Commercial software was used to study various sub-array concepts with the application of EBGs to limit SWs. Two hardware demonstrator array panels were produced and experimentally tested for validation purposes.