Filter for loading interdigital trough line and grounded coplanar waveguide line based on substrate integrated waveguide (SIW)

The invention provides a filter for loading an interdigital trough line and a grounded coplanar waveguide line based on a substrate integrated waveguide (SIW). The filter is composed of three adjacent resonators, wherein two columns of plated through holes with the interdigital trough line in the middle of the plated through holes are shared by the first resonator and the second resonator; two columns of plated through holes with a double-trough line in the middle of the plated through holes are shared by the second resonator and the third resonator; a first port is formed in the middle of one side of the first resonator; L-shaped trough lines are respectively arranged on two sides of the junction of the first port and the plated through holes; a second port is formed in the middle of the other side of the second resonator; L-shaped trough lines are respectively arranged on two sides of the junction of the second port and the plated through holes; the interdigital trough line is formed by connecting four horizontal trough lines which are the same in length end to end; and the double-trough line is composed of two horizontal trough lines with are the same in length. According to the filter provided by the invention, the selectivity of the filter is improved; and the parasitic transmission band of the filter can be inhibited.