Design of a Compact Polarization-Agile and Frequency-Tailored Array Antenna With Digital-Controllable Radiation Beams

In this article, a low-profile compact array antenna using polarization-agile and frequency-tailored capabilities with digital-controllable radiation beams is presented. The antenna element consists of a square patch loaded by four capacitors and four switchable feeding ports which are controlled by a field-programmable gate array (FPGA). The frequency of the resulting structure can be altered from 1.35 to 2.19 GHz based on a compact size by choosing different capacitance values from 0.31 to 3.14 pF. By designing the coding patterns of the digital radiating elements, various radiation beams with three different linear polarization (+45°-LP, −45°-LP, and V-LP) can be achieved and arbitrarily controlled based on one antenna aperture. The simulation and experimental results demonstrate an acceptable agreement, which proves the polarization-agile and beam-controllable characteristic of the designed array antennas at three different frequency bands corresponding to 0.3, 1.0, and 3.0 pF. The multifaceted reconfiguration capability enables it to meet the needs of signal quality stability in many future communication systems.