An antenna arrangement for receiving television signals from a satellite comprises a parabolic (5) which collects the signals and feeds them through a feedhorn (6), then through a polarisation switch (8) and a low noise block to the receiver. The polarisation switch (8) comprises a ferrite rod (16) supported in a dielectric holder (18) within a circular waveguide (14). The ferrite rod (16) is surrounded by a solenoid coil (19) which is energisable to rotate the plane of polarisation of the signals passed along the waveguide, so as to enable the switch to select either horizonally or vertically polarised signals. The current in the coil (19) is switchable between two values, one having a predetermined magnitude in one direction through the coil and the other having the same predetermined magnitude but in the opposite direction through the coil. The current levels are selected such that the corresponding angular positions for the plane of polarisation are +45° relative to the datum position for the Polarisation plane and -45° with reference to this datum position. The dielectric holder (18) has a stepped configuration so as to match the loaded waveguide to the empty waveguide.