Reduce polarized interference

The maximum coupling onto the cable occurs when the polarization of the interfering signal matches the cable run. In most cases, intermittent interference sources, such as handheld two-way radios or tablet computers, are naturally vertically polarized because of the way we hold these items during normal usage. As a result, installations with long vertical runs of cable are more susceptible to EMI/RFI than horizontal runs of similar length.

Figure 1 illustrates how to install cables to improve immunity against vertically polarized interference, and Figure 2 illustrates cable installations that increase susceptibility to vertically polarized interference.

Figure 1. RFI source cross-polarized with long cable run (minimum interference)

Figure 2. RFI source polarization coincident with long cable run (maximum interference)