A Compact, Circularly-Polarized, Substrate-Integrated Waveguide, Millimeter-Wave Beamsteering System for 5G Mobile Terminals

A compact, circularly-polarized (CP), end-fire,
$4\times 1$
continuous beamsteering antenna array implemented using substrate-integrated waveguides for 5G mobile terminals is proposed in this paper. The purpose of this system is to complement the radiation patterns of planar phased arrays on the faces of a typical mobile terminal. The proposed system seamlessly integrates previously-presented antennas and polarizers, with adjustable phase shifters and a feeding network in a multi-layered, single stack, printed circuit board (PCB) for continuous beamsteering in a compact package. Through the use of forward and reverse couplers, and the stacking of the phase shifters on top of the feeding network, a compact form factor of
$7.6\times 4.1\times 0.38\lambda _{o}^{3}$
is achieved. The system was fabricated and assembled through standard PCB processes. The measurements illustrated that the system can achieve a continuous beamsteering range of ±35° with an axial ratio better than 3 dB and a gain variation less than 3 dB. A measured impedance bandwidth (BW) of 8.9% at 28 GHz is also demonstrated. Given its performance, size, ease of manufacture, integrated control lines and single RF feed, the proposed system is a good candidate for 5G millimeter-wave continuous beamsteering in mobile terminals.