The prim. radiation system of a paraboloidal reflector antenna uses a slotted dipole arrangement with diametrically opposed slots (13,14) in the termination of a feeder (2) whose inner conductor (12) is short-circuited by a connecting pin (17) to the outer conductor at the point of attachment of the two halves (15,16) of the dipole. An auxiliary reflector (19) is screwed to an end surface (23) of the cable termination, and the active elements (13-16) are encapsulated in a substantially cylindrical block (18) of low loss dielectric with a length of about one wavelength and a dia. of about 0.3 of a wavelength at the mid-band frequency.
