Ku band ultra-narrow bandwidth microstrip bandpass filter

The invention provides a Ku band ultra-narrow bandwidth microstrip bandpass filter, which comprises a microstrip substrate, wherein the reverse side of the microstrip substrate acts as a grounding metal plate, two sides of the microstrip substrate are provided with a first input/output port and a second input/output port respectively, the obverse side of the microstrip substrate is provided with a first uniform transmission line unit, a second uniform transmission line unit, a first coupling feeder, a second coupling feeder, a third coupling feeder, a fourth coupling feeder, a first open-circuit branch knot, a second open-circuit branch knot, a first folded L-shaped structure unit, a second folded L-shaped structure unit, a rectangular structure unit, a third open-circuit branch knot and a fourth open-circuit branch knot. The Ku band ultra-narrow bandwidth microstrip bandpass filter is good in selectivity, high in out-of-band rejection ratio, small in size, light in weight, planar and low in cost.