RF Detectors, or RF Signal Detectors, are simply devices that are able to give some type of indication that RF energy has somehow been coupled into the device. There are a wide variety of RF detector implementations, as well as thousands of knock-off “bug detectors” or “bug sniffers.” Of concern to RF engineers are RF detectors that are able to absorb RF energy within a desired frequency range and provide useful feedback about the RF energy.
RF Detector Diode or Peak Detector
Many of the RF detector types are based on RF detector diodes. These are diodes that are designed and configured to operate as simple rectifiers that drive a capacitor that holds the peak voltage for a short amount of time slowly discharging the energy into a load. This function is essentially a simple peak amplitude detector. The amount of RF energy coupled into the detection circuit depends on the design of the front-end and the frequency behavior of the diode detector.
RF Power Meter
RF Power Meters or RF Detectors, are more complex circuits that make sure of some type of RF detector technology and additional circuitry to ensure some level of reliability and accuracy to the signal detection. RF Detectors, the term generally indicated more simple detector types, generally outputs a voltage response which is proportional to the RF input signal power. In this way, an RF detector can provide an indication if an RF signal is present and provide an accurate reading of the strength of the input signal.
These types of detectors are often used in transmitter systems to measure the transmitter signal strength. Also, these detectors are used in test & measurement applications where the power level may need to be adjusted precisely, or at least known in some parts of the test setup signal chain. A third possible use is to include an RF detector in a handheld or otherwise portable module with an external omni-directional or directional antenna. In this configuration an RF detector could be used to sense RF signals in the vicinity, or with a directional antenna, more precisely determine the direction of a RF generator (i.e. a rf bug detector or bug sniffer).
More complex RF Detectors, RF Power Meters, may also have some type of data interconnect, such as USB, and provide more detailed information about the RF power coupled into the device, or otherwise be compatible with an API or software suite to allow for visualization of the data.
Other Common “RF Detector Types”