Tips for Finding Hybrid Couplers

A hybrid coupler is a four-port directional coupler that is designed to split power equally. You can find both 90- and 180-degree hybrids. Unlike standard couplers, there is no 45-degree hybrid. Therefore, you need to know about the two types of hybrids and how to get them to accomplish your task before building a project. 

180-Degree Couplers

The 180-degree coupler category includes the rat-race and waveguide magic tees. The rat-race coupler tends to be the more popular option. When shopping for this type of coupler, consider the impedance before purchasing one. 

90-Degree Couplers

These include the Lange, branchline, overlay, edge, and short-slot couplers. The branchline is the most popular 90-degree hybrid coupler. When shopping for this type of coupler, think about your impedance requirements and bandwidth. 

Make a 180-Degree Coupler From a Branchline

In some applications, such as with a monopulse comparator, 180-degree couplers complicate your project’s layout. The good news is that you can get the same result by adding a section to a standard branchline coupler. This will lengthen the input wavelength, therefore altering the impedance. The result is a 180-degree function where a rat-race coupler doesn’t work. If you are shopping for rat-races and cannot find one, this method is also a good option. 

Use Back to Back Couplers for an RF Crossover

By stacking hybrids, you can establish a four-port setup that provides isolation for two RF paths. You should only try this if there is room, and you don’t need a lot of bandwidth. If you are shopping for an RF-RF crossover and can’t find one, this is an option. 

Hybrids are a popular type of coupler. They are designed to create an equal power split in a four-port system. You can use them in a lot of applications if you get the proper option. These tips will help you choose the right coupler and make modifications to your purchase if necessary.