Hughes develops humidity-detecting connector cap to help combat PIM

Research performed by Hughes Electronics and London Southbank University, has found that humidity makes a significant contribution to passive intermodulation (PIM), through the deposition of a layer of salts and other airborne contaminants which interfere with ‘clean’ signal transit.

PIM is a series of resulting signal harmonics and distortions that emerge between two or more interacting signals when transmitted through passive components such as cables and connectors, causing unwanted interference and degradation of wireless communications. 4G, 5G and future generation networks require stricter signal to noise ratios (SNRs) and the issue of PIM must be addressed if cellular capacity is to be maintained.

Though almost impossible to see the salts deposited during the evaporation process are electrically conductive and play havoc with skin effect signal transmission, they instigate surrogate (signal) pathways, causing parallel path and harmonic signals and distortions, which are a root cause of PIM.

To counter the effect Hughes has designed an intelligent IP68 rated cap for connectors with a humidity indicator. The cap which protects open connector interfaces from mechanical damage, dust and humidity is transparent and incorporates an ingenious blue indicator in the top of the cap that visibly turns to pink when it detects the presence of humidity. It is possible to determine the amount of humidity present by the shade of colour, instructional information is provided with each cap to help the user.