The Directional Coupler


Mostly used in radio technology, directional couplers adjust electromagnetic power in a transmission in order to be used on a different circuit. This type of coupler only couples the power going in one direction and is not able to do two directions at once. They are often constructed in a way that, when the lines are set close together, the energy would pass from one to another, typically seen in microwave frequencies.

Extremely Useful

Directional couplers are extremely useful in signal flow. Once placed in the path of a main transmission, the couplers are able to take a small amount of energy and redirect it to one, or multiple, ports that are coupled as well. The amount of coupling offered generally impacts the minimum insertion loss. It is important to remember that with more decoupling there will be a greater loss of transmission power.

Two Types

There are two types of directional couplers. First is the standard directional coupler, which often works with a single couple port as well as a terminated port. The second is a bi-directional coupler, which has a forward and reverse port. There are different versions of the bi-directional coupler, which may often impact which side to couple the forward and reverse ports of the device.

Get the Best Directional Coupler

The parameters to check for a good coupler is based on insertion loss and tap loss. Some couplers suffer from more insertion loss in the transmission, which prevents signal from appearing at the port, while other couplers suffer from lower signal levels than what should be coming out of the port. It is important to discuss the differences with a professional about the different makes and designs in order to get the best coupler on the market, whether it is a standard directional or bi-directional coupler.