C-band Directional Coupler – The Breakdown of the Fundamentals of its Two Components

Directional couplers are oftentimes seen in RF design applications. These are RF passive devices that are utilized for coupling a particular portion of the traveling power in a single transmission line out through another connection or port. Directional couplers are found in a lot of RF design applications, ranging from through line power sensors to transmitter automatic level controls. With that, they’re particularly useful and permits power levels to be sensed without making a direct link with the transmission line holding the power.

There are a lot of directional couplers available in the market, one of which is the C-band directional coupler. As mentioned above, these couplers partner together a certain part of the power that’s traveling through a single transmission line. With C-band frequencies, these frequencies can still be partnered even in adverse weather conditions due to the low frequencies that this frequency band uses.

Let’s now explore some of the fundamentals behind directional couplers.

The Basics of a Directional Coupler

A single directional coupler has four ports in its circuitry. The four of them are more commonly known as the following:

• Port No. 1: Input (Incident Port)
• Port No. 2: Transmitted (Output Port)
• Port No. 3: Coupled (Forward Coupled Port)
• Port No. 4: Isolated (Reverse Coupled Port)

The ones inside the brackets are referred to as alternative names for each port and may be seen on different occasions.

Generally, the main line is the one that’s in between port 1 and port 2. Usually, this is perfect for carrying high amounts of power levels and it may have bigger RF connectors, of course it needs to be a unit of RF connectors for this to be possible. On the other hand, the remaining ports are usually perfect for lower powers as they are only meant to hold a small proportion of the main power line.

Ports 3 and 4 may even possess smaller connectors to tell them from the main line ports of the coupler. Sometimes, the secluded port is terminated with either an internally or externally matched load that would reach 50 ohms.

Now, let’s see the fundamentals that govern C-band frequencies.

The Basics of the C-band frequency

The name C-band is given to this frequency to indicate a certain portion of the electromagnetic spectrum; this includes wavelengths of microwaves that are utilized for radio communications over long distances. It has a frequency range that ranges from 4 to 8 GHz and its slight differentiation contains frequency ranges that are commonly used for satellite communication transmissions. Other uses of the C-band are found in Wi-Fi devices, cordless telephones and weather radar systems.

For satellite communications, as mentioned above, the C-band frequency can perform better even in adverse weather conditions compared to the Ku-band – another frequency band that’s used in other satellite communication systems.

Both of these components can be seen working together in a C-band directional coupler. This passive component is best suited for satellite communications. While the power is being partnered in a single direction, that functionality can still work despite the weather conditions thanks to the aid of the C-band frequency.