Horn antennas with integrated notch filters

In this communication, we present the design of filtering horn antennas with band-stop characteristics obtained through the use of electrically small magnetic resonators. In particular, a split-ring resonator (SRR) etched on a Rogers Duroid RT5870 dielectric substrate is inserted within the metallic flare of the horn at a proper distance from the throat. At around the resonant frequency of the SRR transmission is highly reduced and a single notched-band is obtained. In order to extend the result to dual-band operation, we also present the design of the filtering module made by two SRRs with different dimensions. The validity of the proposed approach is verified through proper sets of full-wave simulations and experiments on fabricated prototypes. The proposed solution is economical, light, electrically small, easily implementable on already existing radiators, and can find application in wideband communication systems affected by narrowband interfering signals.