The invention discloses a slot-
coupling directional coupler based on an integrated substrate gap 
waveguide. The coupler comprises two ISGW 
coupling waveguides with same structure, and each 
coupling waveguide comprises a via hole layer 
dielectric plate and a gap layer 
dielectric plate. One surface of the via hole layer 
dielectric plate is printed with a 
metal ground layer, the other surface of thevia hole layer 
dielectric plate is printed with a periodic circular 
metal patch and a coupling 
microstrip line, and 
metal via holes are formed in the circular metal patch and the coupling 
microstrip line; one surface of the gap layer 
dielectric plate is printed with a coupling 
microstrip line, and the other surface of the gap layer 
dielectric plate is printed with a metal 
ground layer with a coupling gap; the upper surface of each gap layer dielectric plate is tightly connected with the lower surface of the corresponding via hole dielectric plate to form the corresponding coupling 
waveguide; and the two coupling waveguides are tightly connected after 180-degree relative rotation. The slot-coupling directional coupler can overcome the disadvantages of an existing coupler, realizes broad 
broadband and relatively 
high isolation simultaneously, and has the advantages of easy integration, small size, adjustable coupling coefficient, broad 
broadband, relatively 
high isolation, applicabilityfor 5G frequency bands and the like.