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Working frequency band
The working frequency band of attenuator means that only when the attenuator is used in a given frequency range, can the attenuator reach the target value. Because of RF/microwave
The structure is related to frequency. Components of different frequency bands have different structures and can not be used. The attenuator of modern coaxial structure has a wide working frequency band, which should be paid attention to in design or use.
Regardless of the mechanism and structure of power attenuation, the attenuator can always be described by the two-port network shown below.
In the figure, the input power of the signal is P1, while the output power is P2, and the power attenuation of the attenuator is A (dB). If P1 and P2 are expressed in decibel milliwatt (dBm), the power relationship between the two terminals is as follows
P2 (dBm) = P1 (dBm) - A (dB)
It can be seen that the attenuation describes the degree to which the power decreases when it passes through the attenuator. The magnitude of attenuation is determined by the material and structure of the attenuator. The attenuation is measured in decibels, which is convenient for calculating the whole machine index.
Attenuator is a kind of energy-consuming element, which becomes heat after power consumption. It is conceivable that the power capacity of the attenuator is determined after the material structure is determined. If the power of the attenuator exceeds this limit, the attenuator will be burned down. In design and use, power capacity must be defined.
The echo loss is the VSWR of the attenuator, which requires the input-output VSWR of both ends of the attenuator to be as small as possible. We hope that the attenuator is a power consuming component, which can not affect the two-terminal circuit, that is to say, it matches the two-terminal circuit. This factor should be taken into account when designing attenuators.
When the input power changes from 10 mW to rated power, the coefficient of variation of attenuation is expressed as dB/(dB*W). The specific algorithm for the variation of attenuation is to multiply the coefficient by the total attenuation power (W). For example, a power capacity of 50W, nominal attenuation of 40dB attenuator power coefficient is 0.001dB/(dB*W), which means that when input power is added from 10mW to 50W, its attenuation will change by 0.001*40*50=2dB!
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