In the field of telecommunications antennas suitable for portable communication casings, a monopole radio antenna is provided, including an etched conducting surface, including a ground plane, a structure of conducting lines, and a signal injection point in the structure of conducting lines. The structure of conducting lines comprises a first meander conducting line having multiple strands elongated in a first direction, a second meander conducting line symmetrical to the first conducting line in relation to a median line passing in the plane via the injection point and perpendicular to a general direction of elongation of the strands, the two lines starting from the injection point, and a common surface connected to the ends of the conducting lines distant from the injection point. The antenna is less sensitive to radiation efficiency reductions due to the presence of a plastic hood enclosing the antenna.