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Disclosed is a radio frequency semianechoic chamber design with triangular shaped end walls that improved measurement accuracy when compared to a rectangular chamber.
English (United States)
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Radio Frequency Semianechoic Chamber With Triangular Shaped End
Disclosed is a radio frequency semianechoic chamber design with triangular
shaped end walls that improved measurement accuracy when compared to a
Present state-of-the-art chambers for testing electronic devices to the FCC
rules and regulations are large shielded rooms built in a rectangular shape. The
interior walls are covered with carbon impregnated foam to try and absorb the
radio frequency energy that would be reflected by the metallic walls needed for
shielding. The carbon impregnated foam is not capable of absorbing all the
energy, and some of the energy is reflected.
The reflected radio frequency energy produces standing waves between
parallel walls within the structure. A resonant cavity is produced with end-to-end,
side-to-side, and floor-to-ceiling standing waves.
The use of triangular shaped end walls (see figure) changes the reflection
angle of the energy directed at the near-end and far-end walls. This reduces the
near-end to far-end wall standing wave that is created in rectangular shaped
chambers. The reduction in standing waves between the end walls produces a
chamber that has better correlation to an open field test site than equivalent
rectangular shaped chambers.