Directional couplers and methods for tuning directional couplers

A directional coupler formed at least in part in or on a circuit board, the directional coupler comprising:

• a main line positioned in or on the circuit board for transmitting power;
• at least one secondary line positioned in or on the circuit board so as to have a primary coupling portion that is parallel with and spaced apart from the main line, wherein the primary coupling portion defines a coupling region, wherein the primary coupling portion is configured to be electromagnetically coupled to the main line via an electromagnetic field generated during transmission of power via the main line;
• and
• one or more additional coupling lines positioned in or on the circuit board in the coupling region, wherein the one or more additional coupling lines comprise a secondary coupling portion that extends parallel with and is spaced apart from the primary coupling portion, wherein the one or more additional coupling lines comprise a terminal that is arranged on a peripheral edge of the circuit board for selective grounding of the one or more additional coupling lines, whereby grounding of the one or more additional coupling lines adjusts a strength of electromagnetic coupling between the primary coupling portion and the main line of the directional coupler to adjust power transmitted or for manufacturing tolerances to be corrected.