An antenna installation for cellular radio has four antennas ANT 1A, ANT 1B, ANT 2 and ANT 3 mounted on respective sides of a rectangular support 48 and giving rise to four antenna coverage sectors 1A and 1B and sectors 2 and 3. A splitter/combiner unit (SCU) receives three signals (1, 2 and 3) from a base station, and splits signal 1 into two signals 1A and 1B of equal power. The splitter/combiner 5C1 acts as a splitter in transmit mode and a combiner in receive mode. The signals 1A, 1B, 2 and 3 are connected to antennas ANT 1A, ANT 1B ANT 2 and ANT 3 respectively. Split signal antennas ANT 1A, ANT 1B carrying the same transmit signal are not adjacent to one another: they are separated from one another by another sector associated with a different signal, and therefore do not overlap sufficiently to affect communications significantly. This avoids creation of signal interference regions in antenna coverage areas which would lead to signals being partially unobtainable there.