Uhf inner sensor is a kind of uhf antenna which used to receive electromagnetic waves that produced by internal partial discharge of GIS . Therefore, we can use the antenna performance indicators to judging the performance of the sensor. For antenna input impedance, standing wave ratio, gain are the important parameters, so these parameters for evaluating the performance of the inner sensor is of great significance. However, from the perspective of monitoring partial discharge signals, we pay more attention to the sensor output voltage amplitude which is the sensor's output characteristic in the same field environment, Here, we introduce the sensitivity [10] as the main evaluation index of the sensor performance.
To sum up, the input impedance and the sensitivity are the mainly measure of the sensor.