Principle and Elimination of Antenna Effect

The principle of the antenna effect, as described by the laws of electromagnetism, is based on the ability of conductors to interact with electromagnetic fields and radiate or receive electromagnetic energy. Understanding this principle is the first step in devising effective methods to eliminate or mitigate the antenna effect in electronic systems.

One of the primary approaches to eliminating the antenna effect is proper design and layout. In integrated circuits, minimizing the length of metal interconnects and avoiding long, unbroken traces can reduce the likelihood of these structures acting as antennas. Using shielded or grounded vias to connect different metal layers can also help contain the electromagnetic fields and
prevent radiation. In PCBs, carefully routing traces to avoid creating resonant lengths, maintaining proper impedance matching, and using controlled impedance transmission lines can significantly reduce the antenna effect.

Shielding is another effective technique. By enclosing conductors or components in a conductive shield, such as a metal enclosure or a shielded cable, the electromagnetic fields can be confined, preventing them from radiating out or coupling in external interference. The shield should be properly grounded to ensure its effectiveness. Ferrite beads and chokes can also be used to suppress high-frequency noise and reduce the antenna-like behavior of cables. These components act as high-pass filters, attenuating unwanted high-frequency signals while allowing low-frequency signals to pass through.

Filtering circuits are also commonly employed to eliminate the antenna effect. Low-pass filters can be added to the input and output of electronic circuits to remove high-frequency noise that may cause electromagnetic radiation. Common-mode filters, which target common-mode interference (noise that appears on both conductors of a differential pair), are particularly useful in reducing the antenna effect in data and power cables. Additionally, proper grounding and decoupling techniques, such as using bypass capacitors and ensuring a low-impedance ground plane, can help minimize the electromagnetic fields generated by the circuit and reduce the antenna effect.