DEVELOPMENT OF A 180° HYBRID BALUN TO FEED A TIGHTLY COUPLED DIPOLE X-BAND ARRAY

In contrast to conventional arrays, tightly coupled dipole arrays have been shown to provide enhanced broadband (4:1 performance) when placed near a conductive ground plane. However, such arrays cannot practically realize their full bandwidth with integrated feeding elements due to current design limitations. Such feeds also do not fully address the common mode problem which occurs at certain frequencies in the active array. In this effort, we propose and study several feed designs aimed at creating a wide band 180° hybrid balun. It is demonstrated that shielded structures that are not wavelength restrictive can be realized without exciting the troublesome common mode. The presented balun design provides a transition from 100Ω fed twin wire to 50Ω dual enclosed printed stripline that feeds the densely populated dipole array.The Ohio State UniversityNo embarg