A coupler (100,200), in particular a resistive coupler, wherein a port (102, 207) comprises a connector (110, 210), wherein resistors (103, 104, 105, 106, 205, 206) configured as a Wheatstone-bridge, which are adapted to sum or divide incoming or outgoing signals, are arranged at or in the connector (110, 210), wherein a sum port (107, 207) and/or at least two dividing ports (102, 108, 202, 208) are arranged on a substrate (101, 201), at least two resistors are formed on a ceramic substrate, wherein the resistors placed on the ceramic substrate form a first branch of a Wheatstone-bridge, wherein a second branch of the Wheatstone-bridge is formed by a third and a fourth one of the resistors (103, 104, 105, 106, 205, 206) in series configuration in combination with the impedance of a device connectable to the sum port, wherein the connector (110, 210) is a coaxial connector comprising a shell (112, 242, 243), a central conductor (111, 211) and a dielectric material (114, 235, 262) configured to separate the shell (112, 242, 243) from the central conductor(111, 211), characterised in that the shell (242, 243) is divided in a length direction to an isolated shell section and a shell section connected to a body of the connector, wherein the interruption of the shell (242, 243) configured to allow an access to the central conductor (111, 211) of the connector, and wherein at least one ferrite-bead (109, 209) is arranged on or around the connector (110, 210) on the isolated section of the shell forming a balun for transforming an asymmetrical signal of a dividing port (102, 108, 202, 208) into a symmetrical signal. wherein a port (102, 207) comprises a connector (110, 210), wherein resistors (103, 104, 105, 106, 205, 206) configured as a Wheatstone-bridge, which are adapted to sum or divide incoming or outgoing signals, are arranged at or in the connector (110, 210), wherein a sum port (107, 207) and/or at least two dividing ports (102, 108, 202, 208) are arranged on a substrate (101, 201), at least two resistors are formed on a ceramic substrate, wherein the resistors placed on the ceramic substrate form a first branch of a Wheatstone-bridge, wherein a second branch of the Wheatstone-bridge is formed by a third and a fourth one of the resistors (103, 104, 105, 106, 205, 206) in series configuration in combination with the impedance of a device connectable to the sum port, wherein the connector (110, 210) is a coaxial connector comprising a shell (112, 242, 243), a central conductor (111, 211) and a dielectric material (114, 235, 262) configured to separate the shell (112, 242, 243) from the central conductor(111, 211), characterised in that the shell (242, 243) is divided in a length direction to an isolated shell section and a shell section connected to a body of the connector, wherein the interruption of the shell (242, 243) configured to allow an access to the central conductor (111, 211) of the connector, and wherein at least one ferrite-bead (109, 209) is arranged on or around the connector (110, 210) on the isolated section of the shell forming a balun for transforming an asymmetrical signal of a dividing port (102, 108, 202, 208) into a symmetrical signal.