Microwave Engineering Europe - January/February 2008 - (Page 25)

FAST SMALL ANTENNA TEST 25 multiple antennas, i.e. diversity or MIMO terminals. With these terminals it is possible to increase the spectrum efﬁciency and data rate in mobile broadband systems. Diversity and MIMO does not work in a non-reﬂective environment as an anechoic chamber, but in a reverberation chamber it is easy and fast to measure diversity gain or MIMO capacity. In addition, reverberation chambers can also be made much smaller and at lower cost than anechoic chambers. Anechoic chambers were originally developed to measure radar antennas during the Second World War. The method has then continued to be used and is suitable for large antennas, which besides radar antennas, can be antennas for microwave links, satellite antennas, etc. What these antennas have in common are that they are used in an environment with little reﬂections, so called Line-Of- Sight (LOS) conditions. Due to tradition and necessity, there were no alternative measurement chambers, people who developed small antennas also used anechoic chambers. The vision of a very small measurement facility that would give future antenna engineers the possibility to design antennas at their desks lead to the creation of the company Bluetest AB in year 2000 (Figure 1). Bluetest AB Bluetest AB and Chalmers worked very closely together for many years to gradually develop and improve the reverberation chamber technology. Today Bluetest has three products in its portfolio. A small standard chamber suitable for antenna efﬁciency and radiated power (TRP), a High Performance chamber with very high isolation (100 dB) which is also suitable for receiver sensitivity (TIS/AFS), and tailor made mode stirrers to ﬁt any size existing shielded room. Bluetest´s customers can be found in Asia, Europe, North and South America, and they are a mixture of mobile phone developers/manufacturers, mobile operators, companies that develop small antennas and universities. Five large mobile phone manufacturers are among the customers. The High Performance chamber was developed during 2006 and in it, it is possible to measure receiver sensitivity in 5 to 10 minutes per channel compared to much longer times in anechoic chambers. In addition, it is possible to measure antenna efﬁciency, diversity gain and MIMO performance in only one minute. The fast measurement times have attracted a big interest and to date Bluetest has installed six High Performance chambers and received orders for an additional two. Bluetest has since a year ago had its ofﬁces in Gothenburg’s fastest growing region, Lindholmen Science Park. Subcontractors to Bluetest are the shielded room manufacturer Emp-tronic in Helsingborg and the product development company Aggero in Gothenburg. How do Bluetest´s reverberation chambers work? One puts the antenna or wireless terminal, for example a mobile phone, to be measured on a turntable in the chamber. The positioning of the DUT in the chamber is very simple since it is sufﬁcient that it is placed at least 0.5 wavelengths from any wall in the chamber. The next step is to measure transmitted power or complex S12 between the DUT and the three ﬁxed wall antennas. More about how antenna efﬁciency, radiated power, receiver sensitivity as well as diversity gain and MIMO can be calculated is described below. Mastering harsh environments demands Thales Microelectronics, entity of the Thales group, world leader in critical information systems, is an acknowledged expert in the design, development, manufacturing, integration and testing of complex electronics functions for telecommunications, space and defence markets Transceivers up to EHF band Wideband transceivers 2-18 GHz Expertise : High linear power Low phase noise Reliability & high level density Optical communications Product-life management Customer support Applications : Point-to-point to point-to-multipoint radio links Satellite transmissions Antenna Modules Thales Aerospace Division – Microelectronics Tel: +33 299 00 94 00 Contact : samuel.garcia@fr.thalesgroup.com Microwave Engineering ● January/February 2008 ● www.mwee.com 024_025_026_028_029_MWEE.indd 25 24/01/08 15:15:27 http://www.mwee.com

Table of Contents Feed for the Digital Edition of Microwave Engineering Europe - January/February 2008

Microwave Engineering Europe - January/February 2008 Contents News Comment Radio: Raising the Bar for the Radio: Making 802.11n Work Cover Feature: The RF-System-In-Package Trend - Efficient Design with Advanced Design System 2008 Wireless Sensor Networks: The Zigbee PRO Feature Set: More of a Good Thing Very Fast Measurements of Wireless Devices with Small Antennas in Reverberation Chambers WiMAX Update 2008 Bridging the Gap from the CMOS DSP to the Antenna in OFDM Systems Products Calendar

Microwave Engineering Europe - January/February 2008

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