Attenuation:- The term attenuation, usually used in high frequency techniques, is defined as the ratio, expressed in decibels, of the power level or voltage level between two points in a circuit. Clearly, attenuation or (insertion loss) of a component under test will be the ratio, expressed in decibels, of the power absorbed by the load without the component in the line to the power absorbed by the load with the component in the line, when the signal source and the load are perfectly matched.
The passive elements used to control the amount of microwave power transferred from one point to another on a microwave transmission line are called microwave attenuators. Generally, these elements control the flow of microwave power either by reflecting and/or absorbing it in some dissipative elements. Attenuators may be fixed or variable depending on the requirements. An ideal attenuator when placed in a transmission line, must present a good impedance match at both the terminals, i.e. it should be a well-matched reciprocal device. The attenuation is a function of frequency and so due care should be taken if standard attenuation is desired.
Types of attenuators :-
There are following popular types of microwave attenuators :
- Flap or card attenuators (fixed type)
- Variable attenuators
- Cut-off attenuators
- Precision variable attenuators
- High power attenuators
- coaxial attenuator
The above diagram shows the various type of attenuators.