An “antenna” converts electric power into electromagnetic (radio) waves—or the other way around. Any wire carrying an electrical signal makes itself a broadcast antenna by sending out electromagnetic waves and any nearby wire becomes a receiving antenna when its location in the path of electromagnetic waves creates a signal in the wire. If this antenna effect transfers unwanted current and voltage to the receiving wire, it is called electromagnetic interference (EMI). EMI can result in difficult cutting operations and problems with cut quality.
EMI (aka RFI)
• Noise (random signals) and interference (from a different signal source) both function to decrease the quality of the signal you want.
• Noise and EMI (also known as radio frequency interference or RFI) is present in varying amounts in all circuits.
EMI has other effects, such as interfering with radio reception.
• Good operation is achieved when the ratio of signal to noise-plus interference (SNIR) is high. In this discussion, we will focus on increasing SNIR by reducing EMI, but some noise will be reduced as well.
Some factors that increase EMI
• In general, the following factors will increase EMI:
• Longer conductors (sending and receiving)
• Close proximity of sending and receiving conductors
• Higher energy signals on the sending conductor
• Higher frequency signals on the sending conductor
• Capacitive or inductive coupling
• Loose electrical connections
Factors that decrease EMI
• In general, the following factors will decrease EMI:
• Shorter conductors (sending and receiving)
• Greater distance between sending and receiving conductors
• Lower energy signals on the sending conductor
• Lower frequency signals on the sending conductor
• Tight electrical connections