11 Important Attenuator Glossary Terms


An attenuator is an electronic testing instrument that decreases the magnitude or power of a signal. Due to its composition, this device can effectively diminish the amplitude of the signal without compromising signal purity or causing noticeable distortion. Whereas an amplifier increases the magnitude or frequency of optical or acoustic waves, an attenuator causes the amplitude to dissipate for closer examination of composition. The extent of attenuation, or signal power loss, is most commonly expressed in decibels (dBs).

Average Power

The average power of a signal refers to the average amount of energy exerted or transferred through a complex signal over a specific unit of time. Specialty testing instruments are used to measure the average power of various types of signals and beams. Average power of a continuous light beam, for example, is measured with a fiber optic power meter.

Decade Attenuator

A decade attenuator is a commonly used electronic testing device that effectively lowers the amplitude or magnitude of a given signal in incremental steps. It can be used as a standalone device or as a component of a larger system of electronic testing equipment.

Direct Reading

Direct reading refers to the calibration of a particular instrument so that the quantity or quality of a given medium or signal can be measured and read directly from the instrument. This feature eliminates the need for a multiplying constant or additional measurement equipment.

Fixed Attenuator

A fixed attenuator is a unit of electronic testing equipment that is used to decrease the power level of a particular signal by a specified amount. The fixed attenuator accomplishes this while causing little to no reflection. The impedance level (both input and output) are maintained at a level of approximately 50 to 75 ohms while the output signal is attenuated relative to the input signal. A fixed attenuator is commonly used in the improvement of interstage matching in a circuit.

Insertion Loss

Insertion loss refers to the decrease in a load's power caused by the insertion of a separate component or instrument at a given point in a transmission system. This figure is most commonly represented by a ratio measured in decibels and is expressed as follows: the amount of power received at the load prior to the insertion of the exterior device to the amount of power received at the load following its insertion.

N-Type/SMA Connector

An SMA (Sub-miniature Version A) connector to N-type connector adapter is a connection device that is used to connect electronic testing instruments to communications systems. These systems may exhibit power or frequency levels that are too high to form a safe or efficient connection without the use of the adapter. The SMA connection type is comprised of a small, threaded signal connector and is most frequently used to connect handheld testing instruments to high frequency systems while the N-type connection type is most frequently used as the RF or antenna connector.

Power Rating

In regard to electronic equipment, the power rating of a given apparatus (determined by the manufacturer) acts as a guideline to inform users of the maximum amount of power that can be safely used with that apparatus. This limit is most commonly provided to avoid damage to the device caused by overheating, short circuiting, etc., as well as to prevent personal injury and property damage.


Repeatability refers to the proximity and quality of agreement between a given quantity of continuous measurements where all conditions under test (and all characteristics of test equipment) are the same in each test. If consecutive measurement tests reveal a high level of repeatability, the likelihood that the measurements are accurate is increased significantly, whereas a high level of variability suggests questionable accuracy.

Step Attenuator

A step attenuator (available as a manual or programmable device) is an electronic testing instrument used to precisely control and vary the amplitude of a given signal via a system of switches. The composition of a step attenuator provides for a low driving impedance at the load regardless of the position of the switches. This feature enhances the bandwidth potential of the entire circuit at all gain controls.

Variable Attenuator

A variable attenuator is an electronic testing device that allows its user to control the attenuation of a signal with enhanced precision. Variable attenuators work to effectively reduce signal levels for more accurate inspection while measuring the loss or gain of a two-port instrument.