Understanding Isolation in RF Components

Understanding Isolation in RF Components

For those working with radio frequencies and other telecommunications technologies, managing signal loss is just part of the job. When power is coupled or divided, the different internal arrangements of the component being used will produce varying levels of signal loss. Sometimes that loss is reflected or leaked and can mix with the output signal. This creates unwanted distortion in the signal and the engineer may be unable to filter it out.

Low-Isolation Components

If RF power dividers are needed, there are a few choices. Each has its way to handle the signal loss. A reactive power divider has limited isolation and is used in the feed network of an antenna. Couplers tend to have an uneven division of power since the transmission is partially split to another output which is sometimes terminated internally. The most common couplershave four ports channeling the signal through the input while dividing a small portion off to an isolated port and allowing the remaining signal to travel through to the output. These are most often used to measure incident and reflected energies in an RF circuit.

High-Isolation Components

The Wilkinson power divider splits an input signal into two or more equal output signals. This divider battles signal loss with a resistor placed across its outputs and its fourth port internally terminating. No energy is lost with this system. Wilkinson dividers are most commonly used in multi-channel RF systems due to its isolation between the output ports. Having this high isolation allows a combiner’s signals to remain separate and not interfere with the transmission of power. Energy can be dissipated instead of sent through the output.

Whether a person is an engineer working with television transmissions or a hobbyist building a ham radio at home, managing signal loss is important. Making sure to choose the right component will ensure that the project goes more smoothly and the transmitted signal is maintained.

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