Low-cost broadband planar Traveling-Wave Arrays (TWA) with 2-D elements

This paper discusses a latest design of broadband planar Traveling-Wave Array (TWA). The TWA is a class of planar phased array antennas using planar 2-dimensional (2-D) broadband traveling-wave antenna elements closely spaced above a conducting ground plane. To suppress grating lobes, array elements are densely packed, and adjacent elements are strongly coupled to facilitate continuous propagation of the traveling wave and thus minimize phase granularity in the aperture current distribution. This study employs an empirical design approach based on the technique of Active Element Gain Pattern (AEGP). Measured data showed that the design approach has the potential to achieve broad bandwidth and wide-angle beam scan. The 2-D radiators are amenable to low-cost manufacturing process. Some controversial issues in the literature on AEGP and scan impedance, as well as their measurements, are also discussed.