Small reverberation chambers for radio frequency emission measurements: a radio astronomy feasibility study

To use a Reverberation Chamber (RC) below the Lowest Usable Frequency, this thesis applies: multiple receiving antennas; multiple EUT positions; and a modified validation procedure. Emission measurements are then possible down to the first cavity resonance. The design is based on theory and simulations, and validated by on a prototype. The longer measurement times, compare to conventional RCs are acceptable where sensitivity is of concern, e.g. in radio astronomy or defence applications

Reducing the LUF of a reverberation chamber based on the concept of MIMO for electromagnetic emission measurements for radio astronomy applications

The International Centre for Radio Astronomy Research (ICRAR), a joint venture between Curtin University and The University of WA, is involved in a number of radio astronomy projects, and one of the tasks is the testing of equipment for Electromagnetic Compatibility (EMC). In order not to interfere with radio astronomy signals, electrical and electronic equipment close to, or at, radio astronomy sites must have a very low electromagnetic emission. Before an electronic device or system can be installed, it must be tested against stringent emission limits, and for that purpose it is crucial that the test facility has a very good sensitivity. To increase the sensitivity of the EMC measurements it is planned to convert an existing shielded room into a reverberation chamber. Reverberation chambers are in principle suitable for very sensitive emission measurements. However, they have limitations in respect to the frequency range; to test at low frequencies the chamber has to be big, so that the chamber can maintain the uniform field strength within the working volume. Instead of rotating a stirrer only, this paper studies the possibility to extend the usability of a reverberation chamber to lower frequencies by introducing the concept of multiple-input and multiple-output (MIMO) communication channels. This research project employs both measurements and computer simulation using a Finite Element Method (ANSOFT HFSS)

EMC applications for military: Reverberation chamber tests

Electrical and electronic equipment installed on military platforms must have very low electromagnetic emission and good immunity for the whole operational frequency range. Reverberation Chambers (RC) are tools for sensitive emission measurements and immunity tests against strong electromagnetic fields, at a lower cost than other techniques. Method of RC should be suitable for testing Military's electronic devices such as radio or radar system. However, RCs must be large for tests at low frequencies; for example, at 80 MHz are conventional RC must have dimensions up to 7 m by 15 m by 8 m. For military concern, the lowest operation frequency can be as low as 2 MHz (underwater communication can be lower). Conventional RCs can only be used above a certain frequency, the lowest usable frequency (LUF), as they require a minimum mode density (number of modes per frequency interval) in order for the stirrer to perform effectively and alter field distributions. Technique of MIMO RC [1, 2] can make RCs usable down to much lower frequencies; it can mean the dimensions of the chamber can be up to 6 times smaller. However, the composite Q-factor of RCs can be rather low at low frequencies, and this affects the sensitivity, and ultimately usability of an RC. This paper studies the possibility to increase composite Q-factor when RC is used at lower frequencies than conventional method