Overlap in Phase Difference
There is a chance that an interfering source gives the same phase difference as a desired source. Both sources can then no longer be separated based on phase difference. This phase difference applies with loop antennas in the same direction in the far field for an arc of directions and the chance of this is thus higher than with a very large directional antenna (beam). See also Figure 4.
By giving another azimuth direction to the axis on which both antennas are situated, we also give this arc another direction. This can solve overlap in phase difference. A practical solution to this is a third antenna on another axis direction. With interfering sources of relatively large dimensions with respect to the wavelength in the near field, all unexpected phase differences can occur. Turning both loop antennas can then sometimes solve overlap.
Last update: September 24, 2006