PIN-Diode-Based Switchable Polarized Antenna Array with Phase-Shifted Proximity-Coupled-Feed

This paper deals with the development of an antenna array utilizing PIN diodes as switches to modify its polarization. The proposed antenna array implements a phase-shifted proximity-coupled feed with a coaxial probe, yielding in a compact configuration. The array is developed on two layers of 1.6 mm thick FR-4 dielectric substrate to operate at the frequency of 3.5 GHz, which falls inside the sub-6 $\mathbf{G H z}$ frequency range employed by 5G technology. In order to produce switchable circular polarization, a circular phase shifted feedline, whose length is equivalent to one wavelength, is applied to excite the four elements of the array. A decoupling mechanism, in the form of an isolation wall, is incorporated to separate physically each element of the array. The characterization results show that the proposed array array can generate switchable circular polarization by biasing the PIN diodes. In addition, to attain the most favorable outcomes, it is imperative to improve the fabrication technique.