Aspects of the subject disclosure may include, a device having a cylindrical coupler having a metallic shell that surrounds a transmission medium, wherein the cylindrical coupler launches a radio frequency signal from an aperture of the metallic shell as a guided electromagnetic wave that is bound to an outer surface of the transmission medium, and wherein the guided electromagnetic wave propagates along the outer surface of the transmission medium without requiring any electrical return path. An impedance matching element has a conductive trough within the metallic shell, wherein the impedance matching element couples the radio frequency signal to the cylindrical coupler via a coaxial feed point within the conductive trough, and wherein the conductive trough includes a first end forming a short circuit with the metallic shell and further includes a second end forming an open circuit within the metallic shell.