Abstract: A high-frequency antenna unit module for receiving or transmitting a rectilinearly polarized wave including radiating elements in the form of horns and a waveguide supply network. The module has four horns with square apertures which form a bidimensional network in a plane parallel to a reference plane P. The supply network is of the "planar" type having first pairs of opposing sidewalls extending in a direction parallel to P, and of the "tree-structured" type because all of the horns are fed in-phase by T-shaped power dividers. The waveguide sections have sidewall dimensions a and b, where a>b and a=.lambda..sub.c /2. The dimension b is the width of each of the opposing sidewalls extending parallel to P, and a is the height of opposing sidewalls extending perpendicularly to P and connecting each of the first pairs of sidewalls. The network is suitable for propagating the TE.sub.01 mode along which the electric field vector E propagates in parallel with the plane P.