Low-noise attenuator based on microwave directional coupler

Abstract

The invention provides a low-noise attenuator based on a microwave directional coupler. The low-noise attenuator based on the microwave directional coupler adopts a four-port microwave directional coupler as a low-noise attenuator. The four-port microwave directional coupler is made of a low-temperature superconducting metal material; the four-port microwave directional coupler is provided with amicrowave signal input port, a microwave signal straight-through port, a microwave signal coupling port and a microwave signal isolation port; the microwave signal straight-through port is connected with a microwave matching load; the microwave signal isolation port is short-circuit, so that most of the signals coupled to the microwave signal isolation port from the microwave signal input port areshort-circuit to the microwave signal coupling port, and the rest of the signals return to the microwave signal input port and the microwave signal straight-through port; the amplitude of the microwave signal input port coupled to the microwave signal coupling port meets the set microwave signal attenuation requirement; the low noise attenuator is placed in a low temperature environment of a K level. The low-noise attenuator based on a microwave directional coupler can only generate thermal noise equivalent to that generated by the attenuator under the extremely low temperature condition onlyby a low temperature environment without the extremely low temperature condition.

Description

Technical field [0001] The invention belongs to the technical field of microwave quantum precision measurement, and is specifically a low-noise attenuator based on a microwave directional coupler. Background technique [0002] The field of quantum precision measurement requires very low-noise microwave attenuation technology. The existing noise attenuation mainly uses attenuators to achieve signal attenuation. Choose the appropriate attenuator according to your needs, such as 10dB, 15dB, 20dB and other attenuators, which can attenuate the signal to the required size. [0003] According to the microwave theory, the attenuator itself generates thermal noise while attenuating the signal. The magnitude of the thermal noise generated is related to the ambient temperature of the attenuator and also related to the attenuation of the attenuator. If 30dB attenuation is to be generated, the thermal noise generated is almost 290K at a normal temperature of 290K, which will seriously affect t...

AI Technical Summary

Problems solved by technology

However, the equipment that produces mK-level extremely low temperature environment is expensive, and the space inside the equipment is limited. At the same time, the heat generated by the attenuator itself will greatly affect the operating temperature of the extremely low temperature equipment. Therefore, it is very necessary to find a new solution. Reducing Attenuator Thermal Noise Effects

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