The function, related principles, and practical definition of a one-way clutch (starter drive).

What is the function of a one-way clutch?

A one-way clutch is a non-reciprocal attenuator, meaning it provides low attenuation for forward waves and high attenuation for reverse waves. When placed in a waveguide circuit, electromagnetic fields can only pass through in the direction indicated by the arrow on the one-way clutch's housing. In other words, the primary role of a one-way clutch device is to provide isolation, improve the standing wave ratio, and ensure that various components and units operate stably without interfering with each other.

Similar to a circulator, a one-way clutch operates based on the interaction between the magnetic field of electromagnetic waves, ferrite components, and a constant magnetic field. A ferrite plate is placed perpendicular to the wide side of the waveguide, and its surface is coated with a resistive film. A magnet located outside the waveguide generates a constant magnetic field perpendicular to the waveguide's wide side. If the direction of the constant magnetic field is reversed, the direction of passage through the device is also reversed.

The microwave ferrite device in a one-way clutch is manufactured using the gyromagnetic effect of ferrite. Ferrite is a nonlinear, anisotropic magnetic material whose permeability varies with the external magnetic field, exhibiting nonlinearity. When a constant magnetic field is applied, the permeability to microwave magnetic fields differs in various directions, meaning it is anisotropic. Due to these characteristics, when electromagnetic waves pass through ferrite from different directions, they exhibit non-reciprocal behavior. This property is utilized to create various non-reciprocal ferrite components.

A one-way clutch, also known as a one-way filter or one-way isolator, is a device capable of transmitting electromagnetic waves in one direction only. As a non-reciprocal, dual-port microwave ferrite device, it is developed based on the principles of microwave circulators. It was specifically designed for wireless paging transmitters, with functions such as absorbing the energy of interfering signals entering the transmitter through the antenna feeder system from the external environment, protecting the transmitter, and reducing failure rates.