Direct Current (DC)｜Glossary

This page is part of the Electrical Glossary for RF and coaxial systems.

Direct current (DC) is a type of electric current that flows in one direction with a constant polarity. It is commonly supplied by batteries and DC power sources.

DC provides stable voltage and current, making it suitable for electronic circuits, biasing, motor control, and charging applications.

In power transmission, high-voltage direct current (HVDC) is sometimes used for long-distance and high-capacity transmission due to its efficiency.

Compared to AC, DC contains fewer high-frequency components and is generally less affected by noise. However, voltage conversion requires DC-DC converters.

In design, factors such as ripple, transient response, and overcurrent protection (e.g., fuses and electronic protection circuits) must be considered.

In RF and coaxial systems, direct current (DC) is often used for biasing active components such as amplifiers, antennas, and RF modules.

DC can be transmitted through coaxial cables using bias-tee configurations, allowing both RF signals and DC power to share the same transmission line.

Proper isolation between RF signals and DC paths is essential to prevent signal distortion and interference. Components such as DC blocks and bias tees are commonly used for this purpose.

Excessive DC current can generate heat in connectors and cables, affecting contact reliability and long-term performance.

Understanding DC behavior in RF systems is important for stable operation, proper power delivery, and maintaining signal integrity.