A filter-antenna consisting of a monopole antenna and a conical frequency selective surface (FSS) radome was designed and investigated. A coupled-resonator spatial filter (CRSF) was used to design an FSS array with stable performances, and then a specific geometrical layout was proposed to construct a conical FSS radome. We technically investigated the combination of a monopole antenna and the conical FSS radome. Both the simulated and measured results show that the proposed filter-antenna keeps the input reflection coefficient, radiation pattern of the monopole antenna within the designed passband, and reflects out-of-band signals. Such properties of the filter-antenna will exhibit anti-interference capability and low RCS, which can be widely used in military applications.