A meander-line-loaded and microstrip LPF-integrated SIW cavity-backed highly selective wideband filtenna with multiple radiation nulls for short-range radar and satellite communications

Abstract A highly compact microstrip low-pass filter (LPF) integrated, and meander-line-loaded substrate integrated waveguide (SIW) cavity-backed wideband filtenna with multiple radiation nulls (RN) is presented in this paper. A closed-loop quadrilateral slot is removed from the cavity to generate the first RN in the lower edge of the frequency band. Furthermore, an LPF is integrated with the feedline, which creates another RN at the upper edge of the pass band. The incorporation of the meander-line slot in the radiator and elimination of the C-shaped open loop slot from the bottom of the cavity improves the selectivity of filtenna significantly by generating two more RNs at each side of the pass band. The presented filtenna appears to have low profile and compact structure with wideband response of 17% fractional bandwidth (11–13.1 GHz) and 8.56 dBi peak gain in the pass band. In total, four RNs with more than 15 dB out-of-band rejection level and good lower and upper selectivities of 0.65 and 0.05, respectively, are reported, with close agreement between simulation and measurement. These profound properties make the proposed filtenna suitable for short-range radar and satellite communications, modern Radio Frequency (RF) front-end and wireless communication systems.