RF Power Sensor Basics & Selection
RF Power Sensors use used to measure the power level of a signal, they then pass this information to a power meter, which process this and displays this on a screen. There are two main types of power sensor technologies that are used:
Thermal / Heat Based Sensors: These sensors operate by measuring the heat dissipated by a signal that hits a particular load. Since these sensors measure power purely based on heat dissipation, they can be used to measure any waveform including CW, AM, FM, PM, pulsed and many others. Thermal sensors are further divided into two types:
- Thermistor RF power sensors: The thermistor based power sensors operate on the fact that an input RF signal will increase the temperature in an RF load. The thermistor is a semiconductor device with a negative temperature coefficient.
- Thermocouple Power Sensors: This type of sensor is based on the thermocouple principle that metal junctions at different temperatures give rise to a small potential. Thermocouples are true heat based sensors and can provide a true average of the power. They can be used to measure average power levels. Typically thermocouple power sensors are more accurate than thermistor based sensors.
Diode Base Power Sensors: The RF power is incident on a load which dissipates heat. A diode detector is then used to rectify the voltage signal that appears across the load. This rectification is used to calculate the power level of the RF Signal that was incident on the load. Diode based power sensors can measure signals at very low levels (even below -70 dBm). They are also able to respond quicker than sensors based on thermal technology.
The Main factors when selecting a Power Sensor would be the Type, Frequency, Type of signal to be measured, power range required for measurement and the connector type of the power sensor. everything RF lists power sensors from the leading manufacturers. Use the filters to narrow down on the list of products based on your requirement. Download datasheets, compare products and request quotations - The quotation request will be directed to the manufacturer and their distributors in your region, who will get back to you with the details.
