A passive temperature sensor, operation and manufacture of the sensor

The invention relates to a sensor element and a temperature sensor with this sensorelent 1 for passive determination of the temperature using the temperature dependence of the permittivity of at least a ferroelectric material by using the transit time differences within the sensor 1. The sensor element 5 has at least two areas 10, 20 having a different permittivity which are designed such that they have a temperature-dependent penetration depth of the radiation 50th The temperature sensor (1) further still includes at least a signal source (transmitter) 100 of electromagnetic radiation and a Siginaldetektor 200th Furthermore, the invention relates to a method for determining the temperature and an operation method and a manufacturing method for the sensor.