A Multifunctional Full-Polarization Reconfigurable 28 GHz Staggered Butterfly 1-D-Beam Steering Antenna
Ghanshyam Mishra, Satish K. Sharma
Abstract
A novel multifunctional staggered <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\,\,\times12$ </tex-math></inline-formula> Butterfly phased array antenna is proposed at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ka</i> -band (28 GHz) for 5G communications with key features of full-polarization reconfigurability, flexible radiation pattern, and wide-angle 1-D-beam steering performance. The unit cell of the proposed array is a two Butterfly radiating antennas separated by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\lambda \text{g}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda \text{g}\,\,=$ </tex-math></inline-formula> effective wavelength) with two ports, where each Butterfly is a sequentially rotated series-fed microstrip patch antennas. Full-polarization reconfiguration (right-hand circular polarization (RHCP), left-hand circular polarization (LHCP), Linear-X, and Linear-Y polarization) is achieved by suitable excitation of the ports to realize increased system capacity. Flexible radiation pattern with dynamic 3 dB gain-beamwidth from 16° to 90° is achieved to realize a variable cellular range, angle, and gain requirements. The proposed staggered planar array configuration reduces the spacing between the adjacent series-fed linear array to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.45\lambda _{0}$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength at 28 GHz. The proposed array size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\,\,\times12$ </tex-math></inline-formula> Butterfly provides beam steering up to ±63° without any grating lobes. Analytical study using a periodic leaky-wave antenna (LWA) theory is included to provide insights into the radiation characteristics of the Butterfly series-fed linear array antenna. The beam steering characteristics were verified by using measured patterns of the individual branches and by applying the computed array factor. The full-polarization reconfiguration and flexible radiation patterns with sidelobe reduction are implemented and experimentally verified with a 16-channel Analog Devices ADMV4821 RFIC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ka</i> -band beamformer.