Dual-polar Vivaldi antennas for phased arrays with wide-angle scanning

Linearly polarised Vivaldi radiating elements were introduced by Gibson (1979) and have received wide attention due to their broad bandwidths and relative ease of manufacture. Development of Vivaldi elements with a dual-polar capability is more complex because of the non-planar antenna geometry and feed configuration. Also, in array applications, the element design must take account of the complex mutual coupling environment at the array aperture. Prediction of the coupling environment, and in particular the variation of the antenna match with array scan angle, requires use of full-wave electromagnetic modelling techniques. In this paper, we describe the design and evaluation of dual-polar Vivaldi elements optimised for operation in the array environment with frequency bandwidths of up to 3:1 and scan angles of up to 60/spl deg/. The wide-angle scan performance of elements immersed within infinite arrays has been modelled using FDTD techniques. Comparison of FDTD predictions with the measured performance of isolated elements is presented. The wide scan range and bandwidth requirements required the use of customised "blind-mate" connectors.