Electrical currents can oscillate at radio frequencies (from 20 kHz up to 300 GHz) between audio frequencies and infrared frequencies which makes them useable in cables, such as coaxial cables, which can be used to transmit signals for internet, television, telephones, and radios among others. In many situations, these cables need to be split to provide the signal to different sources and this is where a power divider or a power splitter will come into use. Although power splitters and rf power dividers may seem to accomplish very similar goals, they do have key differences that give them different use cases that they are best suited for. The main difference between the two is that power is separated using different resistor configurations. Although they are both passive devices used in radio technology that split electromagnetic power, there are different situations where each different type of device will be used instead of the other.
Basic power splitters typically have two resistors. Power splitters are often used for ratio measurements, leveling, gain and power testing, and leveling loop measurements because it gives better sources matching. They cannot be used to combine power since they are unidirectional. They must be used in ratio systems and level loops instead of a power divider.
Basic power dividers are used in scenarios of simple division of power and typically have three resistors. Power dividers can use three resistors that allow applications to divide power from one source for separate measurements. For example, they can be used to split signals to two separate antennas. Power dividers can also be used as power combiners to make intermodulation-distortion measurements where two separate source signals are combined and used in a device-under-test and the output is measured using a spectrum analyzer. Power dividers can also be used in diversity gain measurements.