Calibration unit and calibration system

A calibration unit for calibrating a measurement device, such as a network analyzer, comprising:

• a first port which is arranged for being connected to the measurement device;
• a calibration module comprising at least three different calibration standards for calibrating the measurement device;
• and
• a switching module configured to connect the first port with one of the at least three different calibration standards of the calibration module;
• wherein the calibration unit further comprises at least one of:
• a daisy chain port which is arranged for being connected to a further calibration unit, to an external power meter, or to a device-under-test, DUT, wherein the first port is connectable to the daisy chain port;
• an internal power meter which is arranged within a housing of the calibration unit, wherein the first port is connectable to the internal power meter;
• or
• an internal impedance tuner which is arranged within a housing of the calibration unit, wherein the first port is connectable to the internal impedance tuner.