Millimeter wave (mmWave) communication systems have attracted significant interest regarding supporting high data
rate of Gigabit/s communications for the new generation of wireless communication networks. MmWave communication systems
have frequency ranges in between 30 and 300 GHz wherein an enormous amount of unused bandwidth is available. Although the
available bandwidth of mmWave frequencies is promising for high data rate communications, the propagation characteristics
of mmWave frequencies are significantly different from microwave frequency band in terms of path loss, diffraction and
blockage, and atmospheric absorption. In general, the overall losses of mmWave signals are significantly larger than that
of microwave signals in point-to-point wireless communications. To compensate the high propagation losses, due to the
limited output power that the current RF active components can deliver in millimeter waves, the use of directional and
beam-steerable antennas become necessary in mmWave wireless systems. The use of directional antennas can effectively
alleviate the signal interference in mmWave communications. High-gain directional antennas can be used at both the
transmitting and receiving ends, resulting in a significantly enhanced Signal-to-Noise ratio (SNR) and improved data
security, and can be used in long-range mmWave point-to-point communications. Moreover, directional antenna beams
with limited spatial coverage need to be steered either electronically or mechanically to obtain a better substitute
link for non-Line of Loss (LOS) communications. Therefore, this dissertation mainly focuses on antenna design for
mmWave frequency band applications. High gain and beam-steerable antennas with the merits of low profile, high gain,
high efficiency and low cost are studied to address the new challenges of high frequency band antennas. First,
waveguide-based technology is employed to propose a new wideband high gain antenna for 60 GHz band applications.
Then, for beam-steerable antenna applications to steer the antenna beam in a specific direction, different
structures of cylindrical lens antennas are studied. First, a compact two-dimensional lens antenna is designed
and proposed at 28 GHz, and then a possible design of a wideband beam-steerable lens antenna is discussed and
presented. Finally, a fully metallic wideband metasurface-based lens antenna is explored. The antenna is
realized based on an array of periodic unit-cells to reduce the loss of the dielectric part in the conventional
lens antennas. This property is exploited to design wideband cost-effective fully metallic antenna at mmWave frequencies.
Reliable Positioning and mmWave Communication via Multi-Point Connectivity
