Page 26 - Antennas for Base Stations in Wireless Communications

Introduction xxv

Several state-of-the art antenna design solutions are presented as
well. This includes outdoor point-to-point antennas, outdoor point-
to-multiple point antennas, and indoor point-to-point antennas. The
various design challenges and tradeoffs of these antennas are also dis-
cussed. Client-device antennas have very critical constraints in terms
of cost and size, which severely limit antenna performance. As for the
base station antennas in point-to-point (P2P) and/or point-to-multipoint
(P2MP) systems, the challenges faced include the tradeoffs among the
performance, cost, size, integration of multiple functions into a single
antenna design, as well as integration of antennas into radios.
Based on the specifications and the antenna design considerations
for WLAN systems, several antenna designs and their practical chal-
lenges and tradeoffs are highlighted as case studies. The performance,
simplicity, cost effectiveness, and manufacturability of the antenna
designs are emphasized. Several applied design innovations are high-
lighted, for example, embeddable antenna on multilayered substrates,
dual broadband antennas, integrated dual-band arrays, and arrays with
broadband feeding network technologies.
A wireless personal area network (WPAN) is a short range network
for wirelessly interconnecting devices centered around an individual
person’s workspace. Typically, a WPAN uses the technology that allows
communication within about 10 meters. There are many technologies
such as Infrared, Bluetooth, HomeRF, ZigBee, ultra-wideband (UWB),
radio frequency identification (RFID), and near-field communication
(NFC), that have been used for WPAN applications. Some of them—
Infrared, Bluetooth, and RFID, for example—are mature commercial
products that have been developed for years. The others such as UWB
and NFC are still being developed.

Chapter 8
Chapter 8 addresses the antenna designs for two WPAN technologies:
RFID for assets tracking and UWB for target positioning.
RFID technology has been developing rapidly in recent years, and
its applications can be found in many service industries, distribution
logistics, manufacturing companies, and goods flow systems. The reader
antenna is one of the key components in an RFID system. The detec-
tion range and accuracy of RFID systems depend directly on reader
antenna performance. The optimal antenna design always offers the
RFID system long range, high accuracy, reduced fabrication cost, as well
as simplified system configuration and implementation. The frequen-
cies for RFID applications, which span from a low frequency of 125 KHz
to the microwave frequency of 24 GHz, the selection of the antenna,
and the design considerations for specific RFID applications feature
distinct differences. Loop antennas have been the popular choice of