Magnetic field sensor and sensor assembly

A sensor assembly for determining and/or monitoring at least one process variable and/or characteristic of a medium in a container comprising a magnetic field sensor, including:

• a magnetoelectric sensor element which can mechanically oscillate, the sensor element having at least:
• one first layer made of a magnetostrictive material,
• a second layer made of a piezoelectric material, and
• at least one electrode made of an electrically conductive material, and electronics;
• the sensor assembly further comprising a device for producing a magnetic field in the region of the magnetic field sensor;
• wherein the magnetic field sensor is designed to induce mechanical oscillations of the sensor element by means of an excitation signal, and to receive the mechanical oscillations of the sensor element and to convert said mechanical oscillations into a reception signal;
• and
• produce the excitation signal from the reception signal;
• and
• determine a variable related to the magnetic field on the basis of the reception signal;
• wherein the magnetic field sensor and/or the device for producing the magnetic field is arranged and/or designed such that the magnetic field can be influenced as a function of a value for the process variable and/or characteristic of the medium, and wherein the sensor assembly is designed to determine and/or monitor the process variable and/or characteristic on the basis of the variable related to the magnetic field.