Abstract: A microstrip coupler having a pair of conductive members electrically connected to the strip conductors of a pair of adjacent microstrip transmission lines and a dielectric element disposed between the walls of the conductive members. The height of the walls of the conductive members is significantly greater than the thickness of the strip conductors and therefore the electric field coupling region between the pair of strip conductors is increased from the relatively thin cross-sectional area of the strip conductors to a greater cross-sectional area provided by the walls of the conductive members. Because of this increase in electric field coupling area the effect of the dielectric material on the coupling factor between the microstrip transmission lines is significant to enable such coupler to provide coupling factors less than 6 db. Further, the coupling factor may be easily controlled by the dielectric constant of the dielectric material and the height of the walls of the conductive members.