Chamber imaging using spherical near-field scanning

We discuss recent measurements performed at the National Institute of Standards and Technology (NIST) that were used to characterize the incident fields within a test volume and to produce images of the test chamber. The probe (figure 1), on a roll-over-azimuth mount, was scanned over a spherical surface enclosing the test volume. A ladder with a small metal plate (figure 2) and a bicycle (figure 1) were both included in the scene. Illumination was alternately provided by standard gain horns mounted on the wall and on a tripod (figure 3) in the first measurement setup and a cassegrain dish mounted on the wall and a circular waveguide on a tripod in setup 2. In setup 1, we used a probe with a gain of about 7 dB, while in setup 2 we used a probe with a gain of about 22 dB.