Understanding the Basics of the Components Behind the Ku-band Directional Coupler

RF couplers are manufactured for the sampling of high frequency signals. It grabs a single frequency signal and classifies it as the input and it provides two outputs – the regular output and the paired output. There are a lot of applications for couplers, such as sampling signals, signal injection, signal generation and a number of other uses. However, just as its uses are plenty, there are also different types of couplers; one example of which is the directional coupler. This four-port device is used to pair together a certain power proportion of the power travelling in a single transmission line out through another connection or port.

Other than that, there is also a wide array of directional couplers for a better signal coupling; one example of which is the Ku-band directional coupler. The Ku-band frequency is a portion of the electromagnetic spectrum with a frequency range that ranges from 12 to 18 GHz. This specific frequency band is used mainly for satellite communications, most especially used for fixed and broadcast services, and for particular uses like for NASA’s Tracking Data Relay Satellite.

The Ku-band frequency in Satellite Communications

In satellite communications, the Ku-band frequency produces a signal with shorter wavelengths that’s powerful and concentrated. With these things in mind, a smaller satellite dish is required to receive the satellite transmissions. In addition, the Ku-band is great in delivering spot beam coverage from satellites.

One downside of the Ku-band frequency is the service coverage it generates is not broad enough when comparing it with another frequency band, namely with the C-band. Also, the higher frequency spectrum the Ku-band makes, it’s more likely to be affected by degradation in signals when compared with the C-band frequency.

The Major Specifications of the Directional Couplers

Every component or system has their very own set of specifications, directional couplers aren’t exempted. There are a couple of specifications that are intertwined with directional couplers. Some of the major ones are listed down below:

• Coupling Loss: Coupling loss occurs between the amount of power that’s lost to the coupler’s 3rd port (The Coupled Port) and to the coupler’s 4th port (The Isolated Port). Let’s assume that there’s a reasonable directivity, the power being ported over unintentionally to the isolated port will be negligible in comparison to the one being ported over to the coupled port.
• Main Line Loss: This loss occurs because of heat (completely separate from coupling loss). This value is then added to the theoretical minus in power that’s ported over to both the coupled and isolated ports (coupling loss).
• Directivity: Directivity refers to the variation between ports 3 and 4 (associated with isolation). This is an estimate of how independent both the coupled and isolated ports are. This is due to the fact that it’s not possible to establish the greatest coupler; there will always be an amount of coupling between every signal paths that will happen unintentionally.
• Isolation: Isolation happens when the power level differ between the input port (port 1) and port 4 (associated with directivity).

It’s imperative for one to learn about the basics of the components of the Ku-band directional coupler. Without the basic knowledge of how both of the components work, one wouldn’t understand how they operate.