Electrostatic waves are often detected with wire dipoles longer than the wave-lengths. The electrostatic directivity pattern of such antennas has lobes roughly perpendicular to those of short dipoles. As a consequence, in a plasma where the electron temperatures are different along (T∥) and across (T⊥) the magnetic field, the thermal noise ''temperature'' is T⊥ if the antenna is parallel to B and (T∥+T⊥)/2 if it is perpendicular. Practical applications for space plasma and wave polarization measurements are given.