focused on introduction of the subject which includes history of the antennas, and types of antennas. The organization of the book also presented in this chapter. presents the fundamental concepts of the antenna. Different parameters of the antenna such as isotropic radiator, radiation pattern, gain, directivity, resolution, antenna apertures, effective height, antenna theorems, antennas efficiency, beam area, beam efficiency, fields from oscillating dipole, field zones, polarization, etc., were defined. presents the field components, power radiated and radiation resistance of oscillating electric dipole, half wave dipole, quarter wave monopole. It also focused on the loop antenna and its modes of operation.presents the antenna arrays. This chapter focused on definition of array, types of arrays, two-element arrays, n-element array, planar arrays, Binomial array, and pattern multiplication. focused on antenna measurements which include the basic concepts of antenna measurements, measurement of directivity, and measurement of gain.