Abstract: A stripline filter having at least two tuned striplines and a directional stripline coupler wherein the coupling path of the directional stripline coupler is located in the signal path between the input and output terminals of the filter. The stripline filter comprises an insulating substrate having a ground conductor affixed thereto and at least two tuned stripline resonators secured to the substrate, the resonators being electrically connected to the ground conductor. The tuned striplines resonate at one-quarter of the wavelength corresponding to the operating frequency of the filter. The directional stripline coupler consists of a pair of spaced conductors, at least one of which forms a part of one of the tuned striplines. The electrical length of the directional stripline coupler is substantially less than the total length of a tuned stripline conductor.