The Danger of Intermodulation Generation by RF Connector Hardware Containing Ferromagnetic Materials.
NAVAL RESEARCH LAB WASHINGTON D C
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This technical memorandum is presented in advance of formal reporting on the in-depth study of mechanisms and means for reducing intermodulation generation IMG in passive radio frequency RF hardware, presently under way at the Naval Research Laboratory NRL. It is imperative that the communication community be again and quickly alerted to the harmonic and IMG interference danger of RF connectors and associated components which contain ferromagnetic materials iron, nickel, cobalt, and their alloys. In a recent search for improved RF connector designs it became evident that the body structure of many of the newer type coaxial connectors and adapaters are being manufactured from stainless steel, type 303, a low permeability 2 ferromagnetic alloy. That such a material could be considered for fabricating RF connectors is difficult to understand because of the known non-linear effects of even small quantities of ferromagnetic contaminants in RF systems. To cut cost, nickel plating, another ferromagnetic material, is apparently also being widely substituted for previously used silver or gold plating of brass stock connectors. If satellite or other weak desired signal communication systems utilizing multicarrier transmitters are to succeed andor survive, such interference generating materials must be eliminated in all transmission elements of the systems. To reverify the ferromagnetic threat and establish the magnitudes of interference, IMG tests of sample RF coaxial hardware were undertaken using the NRL IMG test facility.
- Electrical and Electronic Equipment
- Radiofrequency Wave Propagation