When it comes to tech hobbies, there are few more fitting than radio repair – as one of the original long-range communication methods and the father of the internet, radio relies on some technologies that other fields don’t. Among these are directional couplers, an important type of passive device offered by a wide range of brands and manufacturers.
Directional coupler applications can range from separating incoming and outgoing signals on transmission lines to creating a stable feed between two antennae. They can be used for monitoring the amount of power going through a port – this is done without disrupting the larger circuit, although it sometimes reduces power to the system marginally. These are often the devices that sample signals for broadcasts are routed through before the actual broadcast begins. When it comes to testing in various operating conditions, brands like Werlatone offer resilient products that can continue testing indefinitely with minimal upkeep.
There are multiple styles of directional coupler, mostly depending on the number of directions they will allow power to flow. Although most couplers have four ports, not all of the couplers utilize all of their available ports.
The most basic of these is called a unidirectional coupler, which will only allow power to flow in a single direction at a time. Unidirectional couplers are fixed, which means that they need to be physically rotated if power needs to be rerouted. These devices often contain an internal line which is being terminated where the user can’t see it – for this reason, it can be better to just buy a new bi-directional coupler rather than trying to get into the circuit and solder in a new connection.
Bi-directional couplers are more conventional, and for many, more convenient. Rather than having to mess with your physical system if you need to reverse the flow, they go in two directions. This can be helpful to monitor feedback on a line – at the same time as you check your signal’s strength in one direction, you can insure that you’re not suffering feedback that might damage your audio quality.
Whether you’re buying your coupler to make repairs or simply to improve on a pre-existing system, it’s important to know the types and applications of directional couplers before you dive into the market. Even though radio repair is a niche hobby, it’s got a million options.