RF Coaxial Attenuators, such as Coaxial Fixed Attenuators and Coaxial Variable Attenuators, are used in a wide variety of RF applications to control signal levels, improve impedance matching, and enhance the accuracy of signal generator outputs in test setups. The main use of these components is in coaxial devices, systems, and setups that require signal level control that is either fixed or adjustable.
Fixed coaxial attenuators are more commonly used for impedance matching improvement in environments where the VSWR at a node is high enough to develop unwanted standing waves. This type of attenuator set at a relatively low level provides enough attenuation to prevent the standing wave from building up to that unwanted threshold. As the standing wave bounces between the mismatched nodes through the interconnect, an attenuation placed in between steadily depletes the energy of the standing wave.
In other cases fixed attenuators are used for signal level control where the signal level is generally known and needs to be reduced by a predetermined amount. In high precision scenarios this involves taking into account the total insertion loss and attenuation of all of the interconnects involved in the signal chain between the nodes where having an accurate degree of signal loss is needed. In this case it is often useful to have a fixed coaxial attenuator that is also an adapter if the coaxial connectors on either end of the attenuator are different from each other. This eliminates the need to have a separate adapter or coaxial cable assembly with different connector heads, and may allow for less uncertainty in the interconnect scheme.
Variable attenuators present a more diverse range of use cases than fixed coaxial attenuators. Variable attenuators are used for signal level control, which can include calibrating a test setup where a signal generator is needed, such as receiver sensitivity testing. There are a variety of different types of coaxial variable attenuators, including programmable attenuators, step attenuators, continuously variable attenuators, and voltage variable attenuators. Step attenuators are typically manually adjusted attenuators with fixed attenuation increments that can be adjusted from a low setting to a maximum attenuation setting that engages all of the internal attenuators within the device. Continuously variable attenuators allow for a manual control knob to adjust the attenuation level to a precise amount that isn’t based on discrete steps, which may be useful for tuning a test setup to achieve a very precise signal level output. Voltage variable attenuators are like continuously variable attenuators with the exception that the attenuation level is controlled via a voltage input. Lastly, a programmable attenuator is a variable attenuator with programmable attenuation levels generally set by the a digital communications interface.