A dual-band dielectrically loaded helical antenna for circularly polarised signals has two groups of helical antenna elements. In each group there are at least four such elements and they are connected at their distal ends to a respective feed coupling node and at their proximal ends to a common linking conductor. Each group includes pairs of neighbouring such antenna elements, each pair having one electrically short element and one electrically long element, and the arrangement of the elements is such that in each group the number of pairs in which, in a given direction around the core, the short element precedes the long element is equal to the number of pairs in which, in the same direction, the long element precedes the short element.