Abstract: A multiport radio frequency (RF) signal combiner is described for combining three or more RF signals for application to an antenna. The combiner includes an input port for each RF signal, an output port coupled to the antenna, and a tuning port coupled to a tuning transmission line. The input ports, output port and tuning port are connected to a terminating element. The tuning transmission line is terminated by a fixed or adjustable short-circuit impedance for substantially eliminating the capacitive discontinuity created by interconnecting the input ports. The RF signal combiner can be advantageously utilized in any radio system where it is necessary to multiplex the RF signals from three or more transmitters to a single antenna.