What is RF Attenuator | Benefits or Advantages of RF Attenuator
This page covers RF attenuator types and its basics. It mentions benefits or advantages of RF attenuator.
What is RF Attenuator ?
The device which provides attenuation to radio frequency (RF) signal during its propagation through wired medium is known as RF attenuator. RF attenuators are of two types based on their functionality viz. fixed and variable. Fixed RF attenuator provides fixed amount of attenuation to RF signal. Variable RF attenuator provides variable amount of attenuation to RF signal as per programmable or manual setting varied by program or user. RF attenuators are of two types based on their mounting technique viz. chip and connectorized. Chip RF attenuators are used in RF and microwave circuit designs and are easy to solder on the Printed Circuit Board (PCB). Variable attenuators are further categorized into digital and analog types based on their control type. RF attenuators are made of different type of components in their design such as passive resistors, PIN diodes and FETs.
The figure depicts fixed RF attenuator with two ports. The RF attenuators are used in RF/Microwave circuit designs, Test and Measurement setups, microwave waveguides, wireless links etc. The popular manufacturers of RF attenuators include Mini Circuits, Skyworks, Anaren, Narda Microwave, Hittite Microwave, JFW Industries, EMC RF Labs, RF Micro Devices etc.
Following specifications are considered for selection of appropriate RF attenuator as per application.
• Frequency : The operating frequency range over which RF attenuator provides desired attenuation in the circuit.
• Attenuation : The level of attenuation provided by the attenuator. It is measured in dB (Decibal). The common values in fixed attenuation range include
3dB, 6dB, 10dB, 20dB, 30dB etc.
• Power handling capacity : The maximum power which can be handled by RF attenuator.
• Impedance : The characteristic impedance of the matching line in which attenuator is going to be used.
The common impedance for which attenuators are used are 50 Ohm and 75 Ohm.
• Return Loss : It is the SWR (Standing Wave Ratio) of the attenuator at input and output. It should be as small as possible.
• Accuracy : The attenuation accuracy delivered by the RF attenuator in the RF circuit.
• Packaging : Connectorized (SMA, N-Type etc.), waveguide attenuators, surface mountable etc.
Benefits or advantages of RF Attenuator
Following are the benefits or advantages of RF Attenuator:
➨It is used to provide attenuation to the RF signal.
➨It is used to improve return loss of RF signal by improving impedance matching.
➨It is used to protect receiver circuit of expensive signal analyzers and power meters by reducing signal level
as desired.
➨Variable RF attenuators are used in test and measurement of RF devices by varying attenuation level as per measurement parameters.
➨It avoids overloading of RF components such as mixers and amplifiers in microwave circuit designs by reducing level of the signal to their input.
➨It is used to extend dynamic range of the instrument below the noise floor.
• There are few limitations of RF attenuators as per their design and construction. For one type, VSWR degrades when attenuation increases. For other types of RF attenuators there are bandwidth limitations, performance issues and so on.
Useful RF Attenuator Links
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