  A thermal antenna is an electromagnetic source which emits in its
surrounding, a spatially coherent field in the infrared frequency range.
Usually, its emission pattern changes with the wavelength so that the heat flux
it radiates is weakly directive. Here, we show that a class of hyperbolic
materials, possesses a Brewster angle which is weakly dependent on the
wavelength, so that they can radiate like a true thermal antenna with a highly
directional heat flux. The realization of these sources could open a new avenue
in the field of thermal management in far-field regime.
