A Broadband Cavity-Backed Slot Radiating Element in Transmission Configuration

A planar technology stripline-fed slot radiating element in transmission configuration is proposed. Its main advantages are the broad impedance bandwidth achieved and the property that it only radiates into half-space, which are obtained, respectively, with the use of its complementary strip element and using a cavity-backed slot. A lattice network circuit model is proposed both to explain the behavior of the structure and to establish a design methodology. Its capabilities are shown through the simulation and demonstrated in a proof-of-concept prototype. Measurement results show a unidirectional broadside radiation pattern and a fractional bandwidth of 48%, significantly superior to other slot-based radiating elements found in the literature. The element has the ideal characteristics for building series-fed reconfigurable arrays for wideband applications.