Device for actively improved impedance synthesis

A vector network analyser comprising an impedance control device, the impedance control device comprising:

• a first terminal port arranged for connecting a device under test,
• a high reflective termination connected to a second terminal port,
• a first signal path for a signal travelling between said first and said second terminal port, said first signal path comprising a attenuator and a phase shifter,
• first coupling means arranged for picking up a part of said signal travelling in said first signal path,
• a second signal path arranged for receiving said part of said signal from said first coupling means, said second signal path comprising a correction circuit for applying attenuation and phase shifting to said signals travelling either towards the device under test or away from the device under test between said first terminal port and said second terminal port, and
• second coupling means arranged for coupling back into said first signal path an adapted signal output by said correction circuit.