A Wideband Array Antenna With 1-Bit Digital-Controllable Radiation Beams

In this paper, we propose a <inline-formula> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> low-profile wideband patch array antenna with radiation pattern agility. The digital-controllable antenna element is composed of a square driven patch, a <inline-formula> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> parasitic patch array, and two switchable feeding ports, which are connected to a designed single-pole double-throw switch. Due to the symmetrical structure, individual excitation at the two feeding ports produces a 180° phase difference, giving rise to two basic digital elements of “0” and “1,” respectively. By switching the feeding ports for all antenna elements using a micro-controller unit, the radiation beam of the <inline-formula> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> array antenna can be dynamically reconfigured. To validate the proposed concept, a prototype operating at 5.7 GHz with an overall size of <inline-formula> <tex-math notation="LaTeX">$3.42\lambda _{0}\times 3.42\lambda _{0}\times 0.069\lambda _{0} (\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength at 5.7 GHz) was fabricated and measured. The measured 10-dB return loss bandwidths for all the states cover the frequency band of 5.12–6.32 GHz. The simulated and measured results show close agreement, which proves the powerful dynamical beam manipulation capability of the proposed array antenna.