Electromagnetic anechoic chamber with an inner electromagnetic wave reflection surface and an electromagnetic wave absorption small ball disposed in the chamber

• US 4,931,798 A
• Filed: 06/02/1988
• Issued: 06/05/1990
• Est. Priority Date: 06/03/1987
• Status: Expired due to Term

• Current Assignee: NEC Tokin Corporation (Yageo Corporation)
• Original Assignee: Tokin Corporation (Yageo Corporation)
• Inventors: Kogo, Masanori
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Sotomayor, John B.
• Application Number:
  US07/201,555
• Time in Patent Office: 733 Days
• Field of Search: 342/1, 342/4, 342/5, 342/165, 342/166, 342/169, 342/170, 342/171, 342/173
• US Class Current: 342/4
• CPC Class Codes: G01R 1/18 Screening arrangements against electric or magnetic fields, e.g. against earth's field
• CPC Class Codes: G01R 29/105 using anechoic chambers; Chambers or open field sites used therefor test sites used for measuring on other objects than aerials G01R29/0828; wave absorbing devices H01Q17/00

Abstract

For effectively suppressing echo of an electromagnetic wave emitted from an electromagnetic device (24) disposed in a closed space (13) which is defined by a shielding wall (10), an electromagnetic anechoic chamber comprises an absorption member (28) disposed in the space. The wall has an inner surface which reflects the electromagnetic wave into the space as a reflected wave. The reflected wave is directed to a particular position in the space. The absorption member is located at the particular position. Preferably, the inner space is formed along a substantially ellipsoidal shape having a first and a second focus point (14, 16). The electromagnetic device and the absorption member are locsated at the first and the second focus points, respectively.

Claims

1. An electromagnetic anechoic chamber for providing a closed space for containing an electromagnetic device emitting an electromagnetic wave therein, an echo of the electromagnetic device being suppressed within said closed space, said electromagnetic anechoic chamber comprising:

an electromagnetically shielding wall having an inner surface of a substantially ellipsoidal shape with a first and a second focus point, said inner surface defining said closed space and reflecting said electromagnetic wave into said closed space as a reflected wave;

electromagnetic absorption means located at said first focus point for absorbing said reflected wave to thereby remove the reflected wave from said closed space; and

receiving means located between said first and said second focus points for receiving said electromagnetic wave, said second focus point being determined as a specific point at which said electromagnetic device is located.

2. An electromagnetic anechoic chamber as claimed in claim 1, wherein said shielding wall comprises a plurality of plates which are connected to one another to generally form said substantially ellipsoidal shape.

3. An electromagnetic anechoic chamber as claimed in claim 1, wherein said absorption means comprises a base member of urethane foam and carbon black impregnated in said base member.

4. An electromagnetic anechoic chamber as claimed in claim 3, wherein said absorption means further comprises an additional member mechanically coupled to said base member.

5. An electromagnetic anechoic chamber as claimed in claim 4, wherein said additional member is of ferrite.

6. An electromagnetic anechoic chamber as claimed in claim 3, wherein said base member has a spherical surface.

7. An electromagnetic anechoic chamber as claimed in claim 6, wherein said base member is generally spherical and has a plurality of radially outwardly projecting portions.