The concept of source currents of a radiating source can be employed to express its directivity in some particular cases analytically. For an antenna array, this concept can be extended to the concept of a generalised directivity based on self‐ and mutual radiation intensities, self‐ and mutual radiated powers and excitation currents of array elements. These approaches were applied to examples of the array of two elementary dipoles and the array of two isotropic radiators. Particularly, the evaluation of the directivity of the end‐fire arrays, which are of special attention due to superdirective properties, was treated. Novel closed‐form expressions for the directivity of these arrays with out‐of‐phase excitation were derived. It was observed that the end‐fire directivity can be further enhanced by optimising the excitation currents of the arrays. Their optimal phase difference and corresponding increased directivity were also found analytically. The results were validated by a full‐wave simulator.

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We present a hybrid radiofrequency and microwave photonic link at 25 GHz using the chromatic dispersion of an optical fiber to steer the beam of a three-element planar dipole-based phased antenna array (PAA). Our team has designed and developed an in-house built PAA, experimentally verified its parameters, and successfully demonstrated optically controlled beam steering as measured in an anechoic chamber. Moreover, a detailed analysis of the optically based beam steering in the proposed microwave photonics system has been carried out, with data transmission achieving an error vector magnitude as low as 5.6% for the frequency of 25 GHz and 20 MHz bandwidth.