Antenna and associated measurement sensor

A device including an antenna operative at a wavelength λ, comprising four elementary IFA antennas, each elementary IFA antenna comprising a ground plane, a roof, a short-circuit between the ground plane and the roof and an excitation means, the four elementary IFA antennas being distributed around an axis in a first set of two IFA antennas having substantially equivalent far field elementary radiations and a second set of two IFA antennas having substantially equivalent far field elementary radiations,

• the excitation means of the two IFA antennas of the first set being aligned along a first alignment axis substantially perpendicular to the axis and the excitation means of the two IFA antennas of the second set being aligned along a second alignment axis substantially perpendicular to the axis, the first alignment axis and the second alignment axis crossing at a right angle at one point of the axis,
• the excitation means of the four elementary IFA antennas being fed by radiofrequency signals of like amplitude whereof the phases follow a law which is substantially progressive in quadrature by rotation around the axis (0°, 90°, 180°, 270°), and
• the diameter of the device including the antenna being less than λ/4.