Vivaldi with tunable narrow band rejection

A novel Vivaldi antenna is presented with tunable narrow band rejection characteristics within the overall operating bandwidth. A microstrip line resonator is incorporated within the Vivaldi antenna to give a narrow stop band action. Three varactors are loaded into the resonator and are used for tuning. The stop band can be activated in the frequency range between 2 and 7 GHz to give a very wide tuning ratio of 3.5:1. Good agreements between simulated and measured results are observed, which verify the design concepts