About Bluetest Reverberation Chambers
The Method
A reverberation chamber is a metal cavity which is large enough to support several cavity modes at the frequency of operation. The modes can be stirred to create a Rayleigh distributed transfer function between two antennas inside the chamber. The Q of the chamber is affected by wall losses, leakage, lossy objects as well as the antennas, and can be used to control the average power level of the transfer function. This average level is produced by measuring the transfer function for several stirrer positions and averaging these levels. Reverberation chambers with high Q have for a couple of decades been used for EMC measurements. The Rayleigh statistics is also present in chambers with low Q (down to 100). This makes them ideal to use for testing of mobile terminals designed for use in fading environments.
The last five years the capabilities of reverberation chambers have been extended to accurate measurements of small antennas and active terminals that are designed for use in Rayleigh fading environments. The new measurement capabilities include radiation efficiency of small antennas, diversity gain of diversity antennas, maximum available capacity of multiport antennas for MIMO systems, radiated power of active terminals, diversity gain of active terminals, and receiver sensitivity. All the measurements can readily be done with the terminal located in a position inside the chamber corresponding to free space as well as in talk positions near a head phantom or close to other near-field objects.
The accuracy of the measurements have been verified by comparison to measurements in anechoic chambers and simulations. An extensive benchmarking of several European test facilities for active and passive measurements of small antennas, including the Bluetest chamber, has been conducted by ACE (Antenna Centre of Excellence) and the results are available at http://www.antennasvce.org. The accuracy of the Bluestest chamber is similar or better than measurements in anechoic chambers and the standard deviation is 0.5 dB.
About Bluetest.se
Bluetest AB is a spin-off company from Professor Per-Simon Kildal and his Antenna Group at Chalmers University of Technology. Bluetest AB is developing, manufacturing and marketing reverberation chambers for measuring the performance of small antennas and wireless terminals such as mobile phones both during transmission and reception in a fading environment.
Bluetest's measurement technique is used in the TCO'01 quality marking of mobile phones to measure Telephone Communication Power® (TCP®). Telephone Communication Power is a registered trademark of TCO Development AB.
Bluetest is located at Lindholmen Science Park, Gothenburg, Sweden, in the middle of a cluster of companies working with wireless technologies, the largest of them Ericsson (Wireless communication) and Volvo (Telematics).
About MI Technologies
MI Technologies delivers engineering solutions and advanced products, systems, and software to address a wide range of technical applications where precise measurement, control or data acquisition is required.
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