A coaxial fixed attenuator is a passive device used in radio frequency (RF) and microwave systems that provides a constant signal attenuation value within a specific frequency range. This type of device is widely used in test and measurement, communication systems, and various application scenarios that require precise control of signal strength. The following is key information about coaxial fixed attenuators, recommended brands and models, and how to choose the right attenuator.

　　1. Overview of coaxial fixed attenuators

　　1.1 Definition and working principle

　　Definition: A coaxial fixed attenuator is a device designed to reduce the strength of an electrical signal passing through it. Its attenuation value is fixed and cannot be adjusted. This feature makes it ideal for applications that require stable and predictable signal attenuation.

　　Working principle: The output signal amplitude is reduced by consuming part of the input energy through an internal resistor network. Common structures include π-type and T-type networks4

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　　1.2 Main functions

　　Signal strength control: Reduce the signal level without changing the signal phase or frequency to ensure that the receiving end is not saturated or damaged by an overly strong signal.

　　Matching impedance: Helps maintain the characteristic impedance on the transmission line, reduces reflections and improves the efficiency of the entire system.

　　Calibration tool: Used as a standard to calibrate instruments and meters to ensure the consistency and accuracy of measurement results.

　　2. Key features

　　2.1 Wide frequency range

　　Coaxial fixed attenuators can provide stable performance over a wide frequency range, ranging from DC to tens of GHz, depending on product specifications. For example, Keysight Technologies offers products that cover the frequency range from DC to 50 GHz2

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　　2.2 Accurate attenuation value

　　Provides a variety of preset attenuation value options, such as 3 dB, 6 dB, 10 dB to 60 dB, and has high accuracy within the specified range7

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　　2.3 Flat frequency response

　　Maintains consistent attenuation characteristics throughout the operating frequency band, ensuring that signals at different frequencies are attenuated to the same extent2

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　　2.4 Low standing wave ratio (VSWR)

　　Having a lower voltage standing wave ratio means better impedance matching, reducing the possibility of signal reflections and improving the overall performance of the system3

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　　2.5 Various connector types

　　Supports various types of connector interfaces, such as N-type, SMA, BNC, etc., to facilitate connection with different RF devices6

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　　3. Recommended brands and models

　　The following are some well-known coaxial fixed attenuator manufacturers and their representative products:

　　Keysight Technologies

　　8490D Series: Suitable for applications from DC to 50 GHz, providing precise attenuation and flat frequency response2

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　　8493A Series: Designed for low-cost solutions, providing nominal attenuation values of 3 dB and 6 dB below 12.4 GHz3

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　　8491A Series: Supports a frequency range of DC to 12.4 GHz, with N-type connectors, and provides a variety of attenuation values from 3 dB to 60 dB6

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　　8491B Series: Extends the upper frequency limit to 18 GHz, also provides small attenuation values of 3 dB and 6 dB and larger attenuation steps7

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　　HUBER+SUHNER

　　offers a range of high-quality coaxial fixed attenuators for different power levels and frequency ranges. For example, model 6803.01.A is a single-port attenuator for 4 GHz applications5

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　　4. Where to buy

　　4.1 Online retailers

　　Arrow Electronics

　　offers a wide selection of coaxial fixed attenuators and can be ordered directly through the website.

　　Digi-Key Electronics

　　A well-known electronic product distributor that offers attenuators from multiple brands and has professional consulting services.

　　Mouser Electronics

　　offers a wide range of electronic components and technology solutions, including a variety of RF modules and attenuators.

　　4.2 Contact the manufacturer directly

　　Official website

　　Visit the manufacturer's official website to purchase directly or inquire, get the latest product information and technical support.

　　5. Selection guide

　　Determine your needs

　　Application scenario: Identify the specific use scenario, such as laboratory testing, field installation, or other specific purposes.

　　Frequency and supported technology: Choose the appropriate attenuator type based on the specific frequency range you need to support.

　　Technical requirements

　　Performance indicators: Evaluate key performance parameters such as frequency range, attenuation value, flatness, etc.

　　Environmental adaptability: Ensure that the selected attenuator can operate reliably in the expected working environment, including temperature changes, humidity and other external factors.

　　Cost-effectiveness

　　Budget considerations: Select the most cost-effective attenuator product based on the project budget while ensuring that the necessary performance or quality standards are not sacrificed.

　　Regulatory compliance

　　Certification and standards: Confirm that the selected attenuator meets relevant industry standards and regulatory requirements of the country or region, such as CE, FCC, etc.

　　Supplier support and service

　　Technical support: Select suppliers with good reputation and technical support capabilities to ensure the reliability of after-sales service.

　　Customized services: Some suppliers may provide customized solutions to help customers develop the most suitable configuration according to specific needs.

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