A small parabolic reflector (dish) of revolution, referred to as a paraboloid, is now being advertised as a TV antenna for direct broadcast. Assuming the diameter of the reflector is 1meter, determine at 3GHz the directivity (in dB) of the antenna if the feed is such that
(a) the illumination over the aperture is uniform (ideal)
(b) the upper efficiency is 80% while the spillover efficiency is 85%. Assume no other losses. What is the total aperture efficiency of the antenna (in dB)