An anechoic chamber is a room in which there are no echoes. This description was originally used in the context of acoustic (sound) echoes caused by reflections from the internal surfaces of the room but more recently the same description has been adopted for the radio frequency (RF) anechoic chamber. A RF anechoic chamber is designed to suppress the electromagnetic wave analogy of echoes: reflected electromagnetic waves, again from the internal surfaces. Both types of chamber are usually built, not only with echo suppression features, but also with effective isolation from the acoustic or RF noise present in the external environment. In a well designed acoustic or RF anechoic chamber the equipment under test will only receive signals (whether acoustic or RF) which are emitted directly from the signal source, and not reflected from another part of the chamber.The semianechoic chamber is a shielded room with radio frequency absorbing material on the walls and ceiling (not on the ground). This semianechoic chamber simulates an open field test site, and eliminates any ambient signals that may be present in an open field environment.
Published in Chapter:
Bluetooth Devices Effect on Radiated EMS of Vehicle Wiring
Miguel A. Ruiz (University of Alcala, Spain), Felipe Espinosa (University of Alcala, Spain), David Sanguino (University of Alcala, Spain), and AbdelBaset Awawdeh (University of Alcala, Spain)
Copyright: © 2008
|Pages: 14
DOI: 10.4018/978-1-59904-899-4.ch042
Abstract
The electromagnetic energy source used by wireless communication devices in a vehicle can cause electromagnetic compatibility problems with the electrical and electronic equipment on board. This work is focused on the radiated susceptibility (electromagnetic susceptibility [EMS]) issue and proposes a method for quantifying the electromagnetic influence of wireless radio frequency (RF) transmitters on board vehicles. The key to the analysis is the evaluation of the relation between the electrical field emitted by a typical Bluetooth device operating close to the automobile’s electrical and electronic systems and the field level specified by the electromagnetic compatibility (EMC) directive 2004/104/EC for radiated susceptibility tests. The chapter includes the model of a closed circuit structure emulating an automobile electric wire system and the simulation of its behaviour under electromagnetic fields’ action. According to this a physical structure is designed and implemented, which is used for laboratory tests. Finally, simulated and experimental results are compared and the conclusions obtained are discussed.