Microstrip to microstrip transition

Claim 1

A direct coupling configuration for coupling the sole output of one microstrip line to the sole input of another microstrip line comprising: first and second microstrip lines, each of said lines having only one input port for power and only one output port for power and each including a strip conductor having a longitudinal centerline and separated from a ground plane by a dielectric layer, for propagation of signal within a predetermined frequency range in a TEM mode via said strip conductor, and a coupling hole in said ground plane at a point immediately opposite said strip conductor; said first and second microstrip lines being disposed in backto-back relation with the ground plane of each in direct physical and electrical contact with the other and the coupling holes in registry, and with said centerlines substantially parallel to each other at the place nearest said hole, to provide direct electromagnetic coupling between the two strip conductors, first means for terminating a first one of said microstrip lines in a low-loss impedance different from its characteristic impedance, with said coupling hole intermediate said input port of said first line and said means for terminating, to produce a standing wave thereon upon excitation and to block any significant power transfer therebeyond, and second means for terminating the second one of said microstrip lines in a low-loss impedance different from its characteristic impedance, with said coupling hole intermediate said output port of said second line and said second means for terminating, to produce a standing wave thereon upon excitation and to block any significant power transfer therebeyond, whereby said coupling hole is the sole power output port for said first microstrip line and is the sole power input port for said second microstrip line, said coupling hole being a slot extending transverse to said strip conductors approximately one-half wavelength long in said transverse direction at the wavelength of signal to be accommodated by said circuits and being of a width substantially less than said length and said coupling hole of each microstrip circuit being located at a point of current maximum for said standing wave on said strip conductor so that essentially all of the input power applied to said first microstrip circuit is directly transferred to said second microstrip circuit through said coupling holes with no intermediate transmission medium.