The Need

The original tapered chamber was developed to reduce stray signals normally associated with a more traditional rectangular chamber. In a tapered chamber, a feed antenna is placed at the throat of a tapered section. This chamber design had several problems: the original concept could not satisfy boundary conditions, the wedge absorber scattered the signal, and the low frequency measurements require thick-walled chambers. A tapered chamber design that addresses these issues is needed to advance this field.

The Technology

Researchers at The Ohio State University, led by Dr. Walter Burnside, have developed an enhanced tapered chamber measurement concept design. The novel design includes a TEM antenna, resistive-card that solves the feed problem, and Chebyshev absorber, a wedge absorber that scatters very little when illuminated from the broadside direction. A complete prototype tapered chamber has been constructed to fully evaluate the described enhancements. The center of the cross-pol corresponds to -35dB to -40dB. The prototype functions very well.

Commercial Applications

• EMI/RFI shielding
• Anechoic chambers

Benefits/Advantages

• Resolves basic antenna feed problem
• Polarization control
• Reduced stray signals and back wall absorber volume
• Solves the basic feed problem associated with traditional tampered chambers
• Allows the polarization of the chamber to be easily changed from vertical to horizontal by simply rotating the feed structure, which is not possible with a rigid chamber
• Test zone fields are clean of stray signals and the polarization is directed by the feed horn
• Reduces the volume absorbed by the back wall absorber