Non-Radiating RF Transport in an Anechoic Chamber

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Figure – Simple Anechoic Chamber


An anechoic chamber is a room designed to completely absorb reflections of electromagnetic waves. Ideally anechoic chambers are also isolated from electromagnetic radiation that is outside of the chamber. Anechoic chambers are used to (among other things) test the radiation patterns of antennae and radar. Ideally, only the device under test should affect EM radiation patterns within the chamber. The test equipment, whether it is emitting or receiving radiation, should essentially be invisible within the testing environment.


    • Transmitting and receiving antennas must have a certain shape and occupy a fixed amount of
      space. This limitation cannot easily be overcome.
    • RF (electromagnetic) signals must enter and exit the chamber without affecting
      electromagnetic fields within the chamber.
    • Cabling to antennas will be arranged in arbitrary ways to place antennas as required for
      test. RF signal transport cabling must
      not produce EM fields or be susceptible to them


Unlike copper cabling which radiates and is susceptible to electromagnetic radiation, the EM fields within the core of fiber cable are confined to the core of the fiber due to the difference in the index of refraction between the fiber core and cladding. When applied to the inside of an anechoic chamber, fiber may be routed for any distance, and the fiber may be routed over any path without radiating EM energy and affecting measurements within the chamber. In addition to the fiber waveguide, the fiber optic transmitter (or receiver) must also emit close to zero electromagnetic energy. The Optical Zonu OZ101 series of fiber transmitter/receiver is ideal for this application. The OZ101 package is very small (0.7” x 1.6” x 0.3”) and is shielded for radiation. The modules may operate from 5V or 3.7V batteries, therefore power supply switching noise is also eliminated.

The Optical Zonu OZ101 fiber optic transmitters and receivers plus fiber transport cable are the ideal means of transporting RF signals into and out of anechoic chambers due to immunity to EM fields and no radiation of EM energy. Measurements within anechoic chambers are not affected by bringing radio frequency signals into or out of the chamber. For more information visit

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