Phase shifting network

A phase shifting network including a main power divider having a main input, first and second main outputs, and means for dividing power received at the main input between the first and second main outputs. A first differential phase shifter is provided. The first differential phase shifter has a first input, first and second outputs, and a first phase shift adjuster which can be moved to adjust the phase difference between the first and second outputs. The first input is connected to the first main output and the first differential phase shifter is configured to divide power from the first input between the first and second outputs. A second differential phase shifter is also provided. The second differential phase shifter has a second input, third and fourth outputs, and a second phase shift adjuster which can be moved to adjust the phase difference between the third and fourth outputs. The second input is connected to the second main output and the second differential phase shifter is configured to divide power from the second input between the third and fourth outputs. A control system is configured to drive the first phase shift adjuster and the second phase shift adjuster, such that the degree of adjustment of one of the phase shift adjusters is dependent upon the degree of adjustment of the other phase shift adjuster. The phase difference between the first and second outputs, the second and third outputs, and the first and fourth outputs is substantially equal.