Coupler is a passive device used to transmit signals between different circuits or systems. It is widely used in radio frequency and microwave fields. Its main function is to couple a certain proportion of power from the main transmission line to the secondary line to achieve signal distribution, monitoring or feedback.
How the coupler works
Couplers usually consist of transmission lines or waveguide structures, which transfer part of the signal energy in the main line to the coupling port through the coupling effect of electromagnetic fields. This coupling process will not significantly affect the signal transmission of the main line, ensuring the normal operation of the system.
Main types of couplers
Directional Coupler: It has four ports and can directionally couple part of the input signal to a specific output port for signal monitoring and feedback control.
Power Divider: Distributes input signals to multiple output ports in equal proportions, often used in antenna arrays and multi-channel systems.
Hybrid Coupler: It can divide the input signal into multiple output signals of equal amplitude but different phases. It is widely used in phase shifters and balanced amplifiers.
Key parameters of the coupler
Coupling Factor: Indicates the ratio of the signal power received by the coupling port to the input power, usually expressed in decibels (dB).
Isolation: Measures the degree of signal isolation between unused ports. The higher the isolation, the smaller the interference between ports.
Insertion Loss: refers to the power loss when the signal passes through the coupler. The lower the insertion loss, the higher the signal transmission efficiency.
Standing wave ratio (VSWR): reflects the impedance matching of the coupler port. The closer the VSWR is to 1, the better the matching performance.
Application areas of couplers
Signal monitoring: In radio frequency systems, couplers are used to extract part of the signal for monitoring and measurement without affecting the transmission of the main signal.
Power distribution: In an antenna array, couplers are used to evenly distribute signals to individual antenna elements to achieve beamforming and direction control.
Feedback control: In amplifier circuits, couplers are used to extract a portion of the output signal and feed it back to the input to stabilize gain and improve linearity.
Signal synthesis: In communication systems, couplers can be used to synthesize multiple signals into one signal for easy transmission and processing.
Latest technological progress
With the rapid development of communication technology, the performance requirements of couplers in terms of high frequency, high power and wide bandwidth are constantly increasing. In recent years, coupler products based on new materials and new processes have continued to emerge, with lower insertion loss, higher isolation and wider operating frequency band, meeting the needs of 5G communications, radar systems, satellite communications and other fields.
in conclusion
As a key component in RF and microwave systems, couplers play an important role in signal transmission, distribution and monitoring. Understanding its working principle, type, key parameters and application areas will help to select the appropriate coupler and optimize system performance in actual projects.
Post time: Jan-02-2025
