tion directly to as high antenna efficiency as possible to influence © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology such important parameters as coverage, battery lifetime, and bit rate in the up- and downlinks. For small antennas, this optimization is very hard to do accurately with software, but it is easy with measurements. Because most of the small antennas should have high efficiency over a number of frequency channels and sometimes over several frequency bands, there is a need for a large number of measurements during development and evaluation of wireless products. 12.1.1 Test Chambers for Terminals and Base Stations with Small Antennas Despite their common usage, the traditional test instruments for measuring the antenna efficiency of small antennas or the total radiated power (TRP) and total isotropic sensitivity (TIS) of wireless devices with small antennas (i.e., anechoic chambers) have never been a suitable method for wireless devices to be used in a multipath environment because there are no reflections in an anechoic chamber. Anechoic chambers were originally developed to measure radar antennas during the Second World War. The method is very suitable for large antennas, which, in addition to radar antennas, can be antennas for microwave links, satellite antennas, etc. These antennas have in common that they are used in an environment with few or no reflections-so-called line-of-sight (LOS) conditions. Still, people who developed small antennas had no other choice than using anechoic chambers for characterizing them because no alternative measurement chambers were available. The anechoic chamber technology has continually been improved by using (e.g., near field probe measurements) multiprobe measurements to speed up measure- ment time. However, devices with small antennas are mainly used indoors or in urban environments where there are multiple paths, which are very different envi- ronments from those found in anechoic chambers. A multipath environm