The working principle of a radio frequency (RF) circulator is a microwave device commonly used in RF systems and has a wide range of application fields such as communications, radar, satellite communications, etc. The working principle of the RF circulator is to achieve signal coupling and distribution by utilizing the resonant mode on the annular transmission line.
The RF circulator mainly consists of an annular transmission line and a coupling structure. The annular transmission line is a special type of transmission line, which is composed of a transmission line of the same length to form a closed loop. The characteristic of the annular transmission line is that it has multiple resonant frequencies. When the frequency of the input signal is equal to a certain resonant frequency of the annular transmission line, the signal will propagate multiple rounds on the annular transmission line and finally return to the input port.
The coupling structure is a device used to couple the input and output signals to the annular transmission line. It usually consists of a coupling ring and a coupling insert. The coupling ring is a section of transmission line located next to the annular transmission line and is coupled to it through electromagnetic induction. The coupling insert is a section of transmission line inserted inside the annular transmission line and is coupled through the interaction of the electromagnetic field. By adjusting the positions and lengths of the coupling ring and the coupling insert, different degrees of coupling effects can be achieved.
When the input signal enters the RF circulator, depending on the matching degree between the frequency of the input signal and the resonant frequency of the annular transmission line, the signal will propagate multiple rounds along the annular transmission line. During the propagation process, the signal continuously couples with the coupling structure, and a part of the signal will be output from the output port, while the other part of the signal will continue to propagate on the annular transmission line.
The working principle of the RF circulator can be summarized in the following steps:
The working principle of the RF circulator is based on the resonant characteristics of the annular transmission line and the coupling effect of the coupling structure. Through reasonable design and adjustment, different power distributions and coupling losses can be achieved. This makes the RF circulator one of the important devices in RF systems and is widely used in fields such as communications, radar, and satellite communications. By deeply understanding the working principle of the RF circulator, RF systems can be better applied and designed to improve system performance and reliability.