A reflectarray antenna element including: a patch of electrically conductive material for reflecting an electromagnetic field; a dielectric substrate providing an RF ground; first and second phase control lines of electrically conductive material arranged to interact with electromagnetic radiation with a first polarisation; a first binary switching device having an ON or OFF state disposed between the patch and ground, and configured to selectively electrically couple the patch to ground via the first phase control line; a second binary switching device having an ON or OFF state disposed between the patch and ground, and configured to selectively electrically couple the patch to ground via the second phase control line; wherein the first switching device is a first PIN diode having a diode direction from the patch to the ground; and the second switching device is a second PIN diode having a diode direction from the ground to the patch; a single DC bias input electrically coupled to the patch and configurable to different discrete voltage levels for selectively controlling the states of the switching devices; a substrate structure including first and second layers (12, 35), the patch being located in the first layer, the second layer being said ground, each of the phase control lines being electrically couplable to the ground layer through a conductive via linking the first and second layers; and a third layer; wherein the DC bias input includes a conductive via linking the first and third layers without electrical connection to the ground layer and wherein the DC bias input is electrically coupled to a DC isolation element at the third layer; wherein selective operation of the first and second binary switching devices (24, 26) by means of the DC bias input is configured to provide phase control of electromagnetic radiation dependent on the state of the switching devices, wherein the antenna element is configured to implement 1.5 bits phase control to provide three phase states for electromagnetic radiation with the first polarisation. a patch of electrically conductive material for reflecting an electromagnetic field; a dielectric substrate providing an RF ground; first and second phase control lines of electrically conductive material arranged to interact with electromagnetic radiation with a first polarisation; a first binary switching device having an ON or OFF state disposed between the patch and ground, and configured to selectively electrically couple the patch to ground via the first phase control line; a second binary switching device having an ON or OFF state disposed between the patch and ground, and configured to selectively electrically couple the patch to ground via the second phase control line; wherein the first switching device is a first PIN diode having a diode direction from the patch to the ground; and the second switching device is a second PIN diode having a diode direction from the ground to the patch; a single DC bias input electrically coupled to the patch and configurable to different discrete voltage levels for selectively controlling the states of the switching devices; a substrate structure including first and second layers (12, 35), the patch being located in the first layer, the second layer being said ground, each of the phase control lines being electrically couplable to the ground layer through a conductive via linking the first and second layers; and a third layer; wherein the DC bias input includes a conductive via linking the first and third layers without electrical connection to the ground layer and wherein the DC bias input is electrically coupled to a DC isolation element at the third layer; wherein selective operation of the first and second binary switching devices (24, 26) by means of the DC bias input is configured to provide phase control of electromagnetic radiation dependent on the state of the switching devices, wherein the antenna element is configured to implement 1.5 bits phase control to provide three phase states for electromagnetic radiation with the first polarisation.