An antenna exhibiting a very wide bandwidth with reconfigurable rejection within the band is presented. The proposed topology is versatile in terms of the number of available antenna states and location of the rejection frequencies, and also allows the operation of the antenna in an " all-pass" state. First, a physical interpretation of the rejection mechanism and its corresponding circuit model are presented and validated. The proposed antenna concept is then demonstrated on a 4-state slot bow-tie antenna operating from 1.5 to 5 GHz with various rejection frequencies. PIN diodes are used as switching elements, with particular care taken to minimize power consumption. Simulated and measured return loss, radiation patterns and gain of the fully operational antenna are presented. Finally, we characterize and discuss the overall efficiency-considered here as the most relevant parameter to characterize the antenna filtering performance-both theoretically and experimentally, thereby highlighting the benefit of the proposed topology.