Electromagnetic interference (EMI) and electromagnetic compatibility (EMC) are two important concepts related to electromagnetic fields, involving electromagnetic interactions between electronic devices and between devices and the external environment. Here is the basic knowledge of these two concepts:

Electromagnetic interference (EMI):

1. Definition: Electromagnetic interference refers to the electromagnetic radiation or conduction between electronic devices or between electronic devices and their external environment, which affects the normal operation of the equipment.

2. Cause of occurrence:

-High frequency signal transmission.

-Sudden discharge, such as switch operation of electrical equipment.

-Transient current or voltage.

3. Conduction and radiation:

-Conducted interference is directly transmitted through cables, wires, etc.

-Radiation interference is caused by the propagation of electromagnetic waves in space.

4. Impact:

-EMI can cause interference from other devices, affecting their performance.

-In wireless communication, EMI may cause communication interruption or reduce communication quality.

5. Spectrum:

-EMI can occur in different spectral ranges, including radio frequency (RF) spectrum and microwave spectrum.

6. Preventive measures:

-Use shielding materials, such as shields and shielded cables, to reduce radiation and conduction.

-Using filters to limit the propagation of high-frequency signals.

-Design the layout of ground and power lines to reduce conducted interference.

Electromagnetic compatibility (EMC):

1. Definition: Electromagnetic compatibility refers to electronic devices that are not only unaffected by external electromagnetic interference in their operating environment, but also do not produce unacceptable electromagnetic interference to other devices and the environment.

2. CE mark:

-In Europe, equipment can obtain the CE mark through testing and certification in compliance with EMC directives, indicating that it meets Europe's requirements for EMC.

3. Electromagnetic compatibility testing:

-Radiation testing: Evaluate the radiation electromagnetic field level of the equipment.

-Conduction test: Evaluate whether the device will be affected by external electromagnetic fields.

4. Standards and specifications:

-The International Electrotechnical Commission (IEC) and other organizations have issued a series of EMC standards, such as the IEC 61000 series, which specify how equipment should be tested and designed to ensure electromagnetic compatibility.

5. Preventive measures:

-Reasonable electromagnetic shielding design.

-Use filters and isolation transformers.

-Optimize the layout of equipment's ground and power lines.

6. Regulatory compliance:

-Different countries and regions may have specific EMC regulations that equipment needs to comply with in order to be legally sold and used in the market.

Electromagnetic compatibility is a crucial part of electronic device design, ensuring that devices can operate stably in electromagnetic environments without causing adverse effects on other devices and systems