An electrical measuring system of a six-port circuit includes a delay line and a arithmetic unit. In a first operating mode, an electrical signal can be on the one hand transmitted directly to a first input terminal and on the other hand via the delay line to a second input terminal of the six-port circuit. In an embodiment, the measuring system is configured such that, in the second operating mode, it does not supply a signal to the first input terminal of the six-port circuit and it supplies a reference signal to the second input terminal of the six-port circuit.