LTE-Advanced and Next Generation Wireless Networks: Channel Modelling and Propagation

Chapter 17

Antenna Design for Small Devices

Tim Brown

University of Surrey, UK

Antenna design for mobile communications has, for many years faced challenges due to the size of the mobile terminal often being considerably smaller than a single wavelength at the frequency of operation. Ideally, the antenna at the mobile terminal should be comparable to at least quarter of a wavelength in order to radiate and receive electromagnetic energy with the highest possible efficiency. At frequencies used in current and future cellular bands, this is not normally the case, particularly with mobile handsets and devices small enough to fit in a pocket. Therefore more compacted antennas have to be developed to fit within the physical constraints, which means that efficiency is compromised and also operating bandwidth is often reduced. When the antenna is in use and has user interaction impacting its electrical characteristics, the efficiency is further decreased. Over the years many antennas have been developed and methods have been researched in order to improve the ways in which these problems can be overcome.

For LTE and LTE Advanced, a number of further issues have to be considered with regards to the system [1, 2], which have an effect on the antenna design and are summarized as follows:

• Multiple bands with different centre frequencies will need to be accessed in order to increase the spectrum available that is required to address the anticipated user demand. This is known as “bandwidth ...