DETECTORS
Block Diagram
Figure 4-22. Block diagram of a detector.
The Detector's Function
A block diagram of a detector is shown in Figure 4-22, and if you think a detector looks like a cross between a coupler and attenuator, you're right, but that won't help you much. A detector is essentially a power-to-voltage converter. RF power enters at point A and what comes out at point B is a voltage which is proportional to the RF power.
The reason a detector is used, in place of a coupler, is that there are certain pieces of test equipment and non-RF components (like microprocessors) which cannot handle RF power directly, but can handle an electrical voltage. In these instances, the detector is used to convert the RF power to voltage, which is then sent somewhere else (either within the RF system or to a piece of test equipment) so that a decision can be made based upon it.
If you want to know what a detector looks like, look at the picture of the fixed attenuator in Figure 4-8. They look almost exactly alike. In fact, even RF engineers sometimes confuse the two, which makes for interesting circuit behavior.