All diversity wireless microphone receivers pick up the transmitted RF signal via a pair of antennas. In large multi-channel systems it becomes undesirable to have a set of antennas for each receiver. To remedy this situation Sennheiser  Electronics Corporation has developed a line of distribution systems, the SAS Series. Passive distribution systems reduce antenna signals to unacceptable levels due to splitter loss. Simple active systems, which employ wideband RF amplifiers, can boost everything, even unwanted frequencies, which could cause serious intermodulation problems. The SAS Series combats both of these by employing frequency-selective RF amplifiers, tuned to the wireless system's frequencies. This technique has the advantage of sending a good clean RF signal to the individual receivers and attenuating unwanted RF signals.