A dielectrically-loaded helical antenna has a cylindrical ceramic core bearing metallised helical antenna elements which are coupled to a coaxial feeder structure passing axially through the core. Secured to an end face of the core is a circular laminate board having feed-through holes for receiving the end portions of feeder structure conductors. Coupling conductors on the face of the board that faces the core extend radially outwardly from connections with the feeder structure conductors to plated edge portions of the board. The board is of a diameter substantially equal to that of the core and bridging conductors overlying the plated edge portions connect the coupling conductors to the helical elements. The board incorporates a matching network.