Recent developments on reconfigurable band-filtering antennas

This paper presents implementations of very wideband antennas with reconfigurable band-rejection filtering within the band. The base antenna topology used is a dipole slot bow-tie whose maximal dimension at the lowest matched frequency is only 0.2λ0. The antennas can be operated with 3 different rejection frequencies and in an all-pass mode, using Pin diodes. In particular, it is explained that the filtering performance of such antenna should be assessed in terms of overall efficiency rather than return loss only. Then, the impact of the different dissipative loss sources on the results is studied, thereby demonstrating that the actual filtering performance of the antenna weakly depends on the pin diode series resistance, in contrast with the apparent degradation in terms of return loss. Thanks to an integrated DC biasing network, it is also evidenced experimentally that the antenna radiation patterns are stable both in frequency and in the different reconfigurable states that are matched at a considered frequency.