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The Basic Structure and Technical Index of Coaxial Attenuator

The coaxial attenuator is a kind of energy loss radiofrequency component, which contains resistive material inside. In addition to the commonly used resistive fixed attenuators, there are also electronically controlled quick-adjustment attenuators. Attenuators are widely used on various occasions where power level adjustment is required.

1. The basic structure of coaxial attenuator

The basic material constituting the coaxial attenuator is resistive material. The usual resistance is a basic form of the coaxial attenuator, and the resistance attenuator network formed from it is a lumped parameter attenuator. The attenuator of the corresponding frequency is formed by placing the resistive material in the radio frequency circuit structure of different bands through a certain process. If it is a high power RF attenuator, the volume must be increased, and the key is the heat dissipation design. With the development of modern electronic technology, fast adjusting attenuators are needed on many occasions. This type of attenuator usually has two implementation methods. One is a semiconductor low-power fast-adjusting attenuator, such as a PIN tube or a FET monolithic integrated attenuator; the other is a fixed coaxial attenuator, a resistance attenuation network controlled by a switch. The switch can be an electronic switch or radiofrequency relay.

2. The technical indicators of the coaxial attenuator

The technical indicators of the coaxial attenuator include the working frequency band, attenuation, power capacity, return loss, etc. of the attenuator.

(1) Working frequency band: The working frequency band of the attenuator means that the attenuator can reach the index value when the attenuator is used in a given frequency range. 

(2) Attenuation: Attenuation describes the degree of power reduction after the power passes through the attenuator. 

(3) Power capacity: The attenuator is a kind of energy-consuming element, which turns into heat after power consumption. It can be imagined that after the material structure is determined, the power capacity of the attenuator is determined. If the power of the attenuator exceeds this limit, the attenuator will be burned. When designing and using, the power capacity must be clarified. 

(4) Return loss: Return loss is the standing wave ratio of the attenuator, and the input and output standing wave ratio at both ends of the attenuator should be as small as possible.

3. The main purpose of the coaxial attenuator

(1) Control the power level: The coaxial attenuator controls the output power of the local oscillator in the microwave superheterodyne receiver to obtain the best noise figure and conversion loss to achieve the best reception effect. In the microwave receiver, automatic gain control is realized to improve the dynamic range.

(2) Decoupling components: The coaxial attenuator is used as a decoupling component between the oscillator and the load.

(3) Relative standard: The coaxial attenuator is used as a relative standard for comparing power levels.

(4) Jump attenuator used in the anti-jamming radar: It is a variable attenuator whose attenuation can be changed abruptly. It usually does not introduce attenuation, but suddenly increases attenuation when encountering external interference.

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