Design considerations of arrays as a viewing instrument of radio telescopes

Antenna, the viewing instrument of the radio telescopes, has a major role for receiving the signals from astronomical radio sources. The paper deals with some critical concepts of antenna theories from the engineering point of view, essential for successful operation of the radio telescopes. Different types of antenna feeds suitable for assisting radio astronomical observations considered briefly. Log periodic dipole array with its structural pattern are then critically examined and its gain variations in relation to number of dipoles and different spacing are presented.