An antenna feed for generating signals for an active antenna array including M antennas (115a-115M) for transmitting transmission beams having selected tilt angles, the antenna feed comprising: a digital beamformer operable to receive an input broadband signal and to generate a plurality N of output broadband signals, each having an associated phase and amplitude; a plurality N of transmission signal generators (111a-111n), each operable to receive one of the said plurality N of output broadband signals and to generate a corresponding plurality N of first RF signals; and a feed network (113, 201) having M output ports each of which is configured to be connected to a respective antenna of the active antenna array and wherein the feed network comprises: a power split network comprising multiple power split stages (201-A, 201B, 201C) each of which comprises a respective set of power splitters, each power splitter operable to divide an RF signal received from the previous power split stage over at least two separate paths to provide split signals to the subsequent power split stage, the power split network operable to receive said plurality N of first RF signals and to generate a plurality P of second RF signals, each having an associated amplitude and an associated phase shift applied using a variable phase shifter of a phase shift network of the feed network (113, 201) and wherein P>M>N, and wherein the variable phase shifter is located between two power split stages of the power split network and is adapted to produce said associated phase shifts and is arranged to shift the phase of the input signal by a variable amount that can be selected or tuned; and the phase shift network being operable to supply respective ones of the plurality P of second RF signals to respective ones of the M output ports of the feed network (113, 201). a digital beamformer operable to receive an input broadband signal and to generate a plurality N of output broadband signals, each having an associated phase and amplitude; a plurality N of transmission signal generators (111a-111n), each operable to receive one of the said plurality N of output broadband signals and to generate a corresponding plurality N of first RF signals; and a feed network (113, 201) having M output ports each of which is configured to be connected to a respective antenna of the active antenna array and wherein the feed network comprises: a power split network comprising multiple power split stages (201-A, 201B, 201C) each of which comprises a respective set of power splitters, each power splitter operable to divide an RF signal received from the previous power split stage over at least two separate paths to provide split signals to the subsequent power split stage, the power split network operable to receive said plurality N of first RF signals and to generate a plurality P of second RF signals, each having an associated amplitude and an associated phase shift applied using a variable phase shifter of a phase shift network of the feed network (113, 201) and wherein P>M>N, and wherein the variable phase shifter is located between two power split stages of the power split network and is adapted to produce said associated phase shifts and is arranged to shift the phase of the input signal by a variable amount that can be selected or tuned; and the phase shift network being operable to supply respective ones of the plurality P of second RF signals to respective ones of the M output ports of the feed network (113, 201). a power split network comprising multiple power split stages (201-A, 201B, 201C) each of which comprises a respective set of power splitters, each power splitter operable to divide an RF signal received from the previous power split stage over at least two separate paths to provide split signals to the subsequent power split stage, the power split network operable to receive said plurality N of first RF signals and to generate a plurality P of second RF signals, each having an associated amplitude and an associated phase shift applied using a variable phase shifter of a phase shift network of the feed network (113, 201) and wherein P>M>N, and wherein the variable phase shifter is located between two power split stages of the power split network and is adapted to produce said associated phase shifts and is arranged to shift the phase of the input signal by a variable amount that can be selected or tuned; and the phase shift network being operable to supply respective ones of the plurality P of second RF signals to respective ones of the M output ports of the feed network (113, 201).