A brief discussion on the characteristics and working principles of transmission lines

Infineon / Mitsubishi / Fuji / Semikron / Eupec / IXYS

A brief discussion on the characteristics and working principles of transmission lines

Posted Date: 2024-02-03

A transmission line is a cable or wire used to carry signals between electronic devices or circuits. The design and selection of transmission lines play an important role in data transmission and communication systems.

Voltage and current travel across a pair of transmission lines. As shown in the figure below, assume that our signal is a sine wave with a single frequency, but the frequency is very high. As a result, during the propagation process on this transmission line, the voltage and current at each point on the line change with the position (z) and time

For transmission lines, the usual research method is to conduct microscopic research on a certain small section. Use the idea of ​​calculus to select a small section. This small section has distributed resistance, distributed inductance, distributed conductance, and distributed capacitance.

The characteristics and working principles of transmission lines are as follows:

1. Signal transmission: Transmission lines are used to transmit signals between circuits, which can be analog signals or digital signals. It provides a physical path that enables signals to travel between source and destination.

2. Transmission medium: The physical structure of the transmission line can use different transmission media, such as metal conductors, optical fibers, or air. Selecting the appropriate transmission medium depends on application needs, distance, bandwidth requirements and environmental conditions.

3. Transmission line parameters: Transmission lines have some important parameters, such as impedance, transmission speed, bandwidth, attenuation, delay, etc. These parameters are critical to the performance and quality of signal transmission.

4. Impedance matching: Signal transmission on transmission lines requires impedance matching to ensure optimal signal transmission and minimal reflection. Impedance matching can be achieved by using suitable transmission lines and appropriate terminating resistors.

5. Signal loss: The transmission line itself will introduce signal attenuation and distortion. Therefore, in long-distance transmission and high-speed signal transmission, signal loss needs to be considered, and appropriate measures should be taken in the design to compensate and correct the signal.

6. Transmission line routing: Good routing of transmission lines is very important to reduce signal interference and crosstalk. Reasonable wiring methods include avoiding electromagnetic field interference and cross-interference, and reducing the length and crossover of signal transmission paths.

Transmission lines are widely used in various application fields, including computer networks, communication systems, audio and video transmission, sensor networks, etc. Understanding the characteristics and working principles of transmission lines is critical to designing and optimizing data transmission systems.

Review Editor: Huang Fei

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