Signal combining apparatus

A radio frequency (RF) signal combining apparatus comprising:

• an input port for receiving an input signal from a signal generator;
• an output port for outputting a signal to a signal analyser;
• a plurality of test ports for connecting the apparatus to a plurality of devices under test (DUTs), the apparatus further comprising:
• a splitter for dividing a signal received at the input port into a plurality of signals;
• a plurality of transmit signal paths, each of the plurality of transmit signal paths comprising a switchable gain stage, the switchable gain stage comprising an amplifier and an attenuator and being operative selectively to connect an input of the gain stage to either the amplifier or the attenuator, such that the input signal is either amplified or attenuated by the gain stage;
• a plurality of receive paths;
• a signal relay, the signal relay being configured to receive one or more signals through one or more of the plurality of receive paths and to output a single composite signal to the output port, the single composite signal output to the output port containing the signals received from the one or more of the plurality of receive paths wherein the apparatus further comprises a plurality of duplex combiners which are each configured to:
• receive a signal from one of the plurality of transmit paths;
• transmit the signal from the one of the plurality of transmit paths to one of the plurality of test ports;
• receive a signal from one of the plurality of test ports;
• and
• transmit the signal received from the one of the plurality of test ports to one of the plurality of receive paths.