The Bluetest patented technology (U.S. Patent No. 7 286 961, U.S. Patent No. 7 444 264, Japanese Patent No. 4 528 480, European Patent No. 1 269 203) represents a paradigm shift for measuring wireless devices used in a multi-path environment. With the Bluetest chambers, wireless performance can be optimized in minutes or hours compared to days or weeks using traditional anechoic chambers. The test chamber market for wireless devices with small antennas has for, a too, long time been dominated by anechoic chambers. Anechoic chambers were originally developed to measure radar antennas during the Second World War. Tests in anechoic chambers, i.e. without any reflections and fading, are natural and required for large antennas that are used in a Line-Of-Sight (LOS) environment. It is, however, a slow and unsuitable way to measure small antennas that normally are used in environments with a lot of reflections resulting in Rayleigh fading, such as indoors and urban environments. Such a fading multipath environment can be emulated by a reverberation chamber.
The reverberation chamber is usually a metal-box, i.e. a cavity, with different sizes in its three dimensions. The dimensions must be large enough to allow multiple reflections to combine to several cavity modes with associated resonance frequencies within the chamber, at the frequency of test. The Rayleigh fading is achieved by so-called mode stirring. The Bluetest reverberation chambers are provided with several mode stirring techniques; two translatable metal plates, a rotating platform, and three switchable wall antennas. The measurement technology as well as the details of the Bluetest chamber including the stirring techniques are protected by granted patents and patent applications. The mode stirring techniques are important for achieving good accuracy, and they allow the chambers to be smaller than otherwise without efficient mode stirrers.
In a few years we believe Bluetest´s measurement technology will be the dominating test technology for all wireless products with small antennas, since it is:
It is today the only technology for direct tests of terminals with MIMO and diversity antennas, key technologies for new mobile broadband systems such as 802.11n, LTE and WIMAX.
For more detailed information about the Bluetest technology, have a look into the literature and white papers.
