Design of a Beam Switchtable Superdirective Dipole for IOT Gateway

In this paper, a switchable beam and super-directive Electrically Small Antenna (ESA) dipole deployed at an IoT network gateway at 868 MHz is presented. It consists of one fed dipole and one loaded parasitic dipole. The nature and value of the load are obtained using the Uzkov equations, allowing determining current weighting coefficients in the case of two separately fed antennas, in order to maximize the gain and the directivity in a given direction. Reconfigurability in two directions is achieved using a pair of anti-parallel PIN diodes to steer the beam to the desired direction. The array final dimensions are 109 x 43 mm(2) (0.3 lambda x 0.1 lambda) generating a high directivity of 6.8 dBi in simulation and 6.7 dBi in measurement at 868 MHz for each beam in the azimuth plane.