Conclusion
Beam-steering is a key enabler for millimeter-wave terrestrial networks.
With the introduction of 5G-Advanced and 6G networks in the coming
years, commercialization of beam-steering antennas will enable the
telecommunication industry to establish a new network infrastructure. We
can classify beam-steering antennas for such networks into four
categories as described in this article. These are (i) phased array
antennas, (ii) quasi-optical systems, (iii) leaky-wave antennas, and
(iv) metamaterials and metasurfaces. Each of these categories has their
own set of merits and demerits in terms of complexity, bandwidth, cost,
power requirements, and beam-steering capabilities. Table 1 compares and
summarizes the four categories with these parameters. Even though
beam-steering antenna technology has advanced significantly over time,
there are still some key challenges that need to be addressed before
they get incorporated into the network. To highlight a few, these
challenges include (i) high complexity, cost of fabrication and power
requirements for intelligent metasurfaces, (ii) out-of-band shadowing
because of metasurfaces, (iii) power requirements of phased array
antennas, and (iv) mass production of 3D-printed quasi-optical systems.
Additional figures and links to videos can be found in the Supplementary
Information.