A Low Sidelobes Miniaturized SIW Filtering Horn Antenna Loaded with Slow-Wave Metal Posts

A low sidelobes substrate integrated waveguide (SIW) H-plane horn filtering antenna is proposed in this paper, by using a trapezoidal resonant cavity and loading slow-wave metal posts. By cross couplings of two operating modes (TE
102
, TE
201
) and an out of band mode (TE
101
) in a trapezoidal resonant cavity, two radiation nulls are introduced on the gain curve, achieving filtering response. The longitudinal length of its flared section is shortened about 57%. Slow-wave posts are loaded to redistribute the electric field at the radiation aperture to a tapered amplitude distribution and a uniform phase distribution, depending on the capacitance and the slow-wave effects. Two radiation nulls can be observed at 14.2 and 18.48 GHz, with a significant decrease in realized gain below -48 and -31 dBi. The H-plane sidelobe levels (SLL) are less than -20 dB within the passband. And it can reach - 39.9 dB at 16 GHz.