What are RF Rotary Joints?

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Editorial Team - everything RF

Jan 3, 2019

RF Rotary Joints are the electro-mechanical components used to transmit RF signals between stationary and movable parts of a system.

In some applications, a stationary RF line needs to be connected to moving components of a system, like that of an aviation radar, where the radar antenna is constantly rotating and is connected to a stationary ground system through a cable. Rotary Joints allow these types of connections with low losses and minimal variation in performance while they are rotating.

RF Rotary Joints can broadly be divided into three types:

Coaxial Rotary Joints: These rotary joints have coaxial input and output terminals. One of the connectors will rotate while the other one will be fixed. The power handling capacity and frequency range of coaxial rotary joints are restricted by the power/frequency limits of the connectors.

Waveguide Rotary Joints: These rotary joints have a waveguide interface at the input and output terminals. One of the terminals rotates while the other one is fixed. The operating frequency of this type of rotary joint is limited by the waveguide size.

Waveguide to Coaxial Rotary Joint: These rotary joints have a waveguide interface at one terminal and coaxial interface at the other terminal. In this case, the operating frequency is limited by the waveguide size, the power is limited by the coaxial part.