CCMC50 Common Mode Noise Filter

Noise filters are nothing new and are often used for transmitting purposes. They are used to prevent unwanted radiation via the coax shielding. It is less known that they can also suppress unwanted radiation when receiving signals, especially when an active antenna is used. However, in this case, the situation is reversed: en route to the antenna, unwanted interferences from electric home appliances can be effectively eliminated.

This Coaxial Common Mode Choke (CCMC50) has been especially optimized for maximum common mode noise rejection of >30dB wide band in the frequency range of 500kHz – 50MHz. With slight limitations a much wider frequency range is covered. This is possible by using a cascaded system of ferrite cores with various frequency dependent material properties, combined with high quality PTFE coaxial cable. We recommend to connect the CCMC50 as closely as possible to the receiver.

For the highest demands we still offer the proven Common Mode Noise Filter CCMC30, which is specially optimized for maximum Common mode noise rejection of guaranteed> 30dB broadband in the reception range from 150kHz – 30MHz.

With the CCMC50 a reasonably priced version is now available with the following minor limitations against the CCMC30:

Common mode noise rejection guaranteed> 30dB, broadband in the reception range from 500kHz – 50MHz instead of starting at 150kHz. Starting with the medium wave over short wave up to the 6m amateur radio band, which should be sufficient for most applications.
Not suitable for outdoor use because it is not splashproof.

With regard to efficient noise suppression, the CCMC50 is not very much different from the galvanic isolator GI1000. However, the CCMC50 performes down to lowest frequencies including DC voltage, in contrast to the GI1000, which blocks DC voltages and very low frequencies. The CCMC50 can thus be connected directly to the coax cable which passes the supply voltage or the control signals to the active antenna. A series connection of the GI1000 directly connected to the receiver followed by the CCMC50 right behind the power inserter may result in an even better performance.

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