The term filtenna  refers to a class of microwave components that, being able to perform both filtering and radiation operations, have been widely investigated for reducing the cost and space occupancy of a microwave system. In most cases, filtennas are designed by inserting a filtering element with a frequency-dependent behavior in the structure of a standard antenna. Given their wide operation bandwidth, which often exceeds the required one, waveguides and horn antennas have been extensively used for this purpose  - . Moreover, by properly choosing the topology of the filtering element and by loading it with non-linear elements, the polarization state and power level of the incoming wave can be used as further discriminating characteristics between signals  - .
Barbuto, M., Lione, D., Monti, A., Vellucci, S., Bilotti, F., Toscano, A. (2021). Filtennas with frequency- and time-domain selectivity properties. In 2021 International Conference on Electromagnetics in Advanced Applications, ICEAA 2021 (pp.33-033). Institute of Electrical and Electronics Engineers Inc. [10.1109/ICEAA52647.2021.9539537].