RF mixers convert RF power at one frequency into power at another frequency to make signal processing easier and more efficient. The frequency that is to be shifted is applied at the RF input and the frequency shifting power or voltage (from a local oscillator, LO) is applied to the RF mixers LO port, resulting in two outputs at the mixer Intermediate Frequency (IF) port. For a given RF signal, an ideal mixer would produce only two IF outputs: one at the frequency sum of the RF and LO, and another at the frequency difference between the RF and LO. Filtering can be used to select the desired IF output and reject the unwanted one, which is generally called the IF image.  Configurations available for RF mixers can be surface mount, flat pack, through hole or plug-in, connectorized, and waveguide assembly.