Mobile and body-centric antenna measurements

In this chapter we look at the key issues that are unique to the measurement of this class of antenna, and we start by considering both far-field and near-field techniques for radiation pattern measurement. We then consider the measurement of return loss and hence the antennas' operating bandwidth. In the practical use of mobile devices, there are no RF cables connecting them, but for S-parameter and pattern measurements a cable usually exists and it can have significant influence on the resulting measurements, and in section 9.5 we show how the use of optical fibre connections is solving this problem. The human body has a high dielectric constant and so antennas mounted close to the body operate differently than in 'free space', so in section 9.6 we consider the issue of 'on-body' antenna measurements both on a live subject and on the use of phantoms. For electrically small antennas efficiency is very important and in section 9.7 we consider the measurement of efficiency via both radiation pattern measurement and the Wheeler Cap method, where we report an improved method well suited to body-centric measurements. Finally we consider the measurement of UWB antennas, noting that 'radiation pattern' has less importance than pulse fidelity in many UWB applications.