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What Are Different Power Splitter Types For DAS

March 23, 2023

What Are the Different Power Splitter Types for DAS?

There are three main Power Splitter topologies, each with its own trade-offs. Having a fundamental knowledge of these differences will help you select the best one for your application.

A DAS needs to amplify and distribute signals from any number of signal sources, including off-air (rooftop) antennas, BTSs on the roof, or small cell technology from off-air donors.

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Reactive Power Dividers

The RF industry has many power splitter types to choose from when it comes to driving an antenna system. These include reactive power dividers, resistive power dividers, and hybrid power dividers.

Reactive power divider, also known as quarter-wave transmission line (QWT) dividers, are a common choice in distributed antenna systems because of their efficiency, low insertion loss, and port isolation. They can be fabricated using waveguide, stripline, microstrip, transformers, and other technologies.

One of the more common reactive power dividers is the Wilkinson power divider, which can be configured as an N-way device. It's a relatively simple design that uses two parallel, uncoupled quarter-wave transmission lines to divide the input signal evenly into multiple output ports.

These dividers are available with a variety of output ports and connectors. They are ideal for driving antenna arrays and other microwave applications. They can also be used as power combiners.

Resistive power dividers are less expensive to manufacture and can be designed into a variety of circuits. However, they are not as efficient as reactive power dividers and are not a good choice for distributing high RF powers.

This is because resistive dividers use two resistors in place of a single one to distribute signals from the input port to the multiple output ports. The resistors in this type of divider have an output impedance that is different from the system impedance, which increases the power dissipation.

Some resistive power dividers also incorporate a transformer, which further increases the power dissipation. This is especially true for dividers that are configured as N-way devices.

Another option for a reactive power divider is the directional coupler, which has asymmetrical output ports that direct signals to specific inputs. These directional couplers can be used for applications such as intermodulation distortion measurements, in which the carrier signals are required to be in phase with each other to be effective.

Besides being able to combine signals, a power divider can perform vector addition or subtraction of signals as well. This can be useful for a variety of applications, including wireless communication, IMD measurement, and even the calibration of network analyzers and other instruments.

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Resistive Power Dividers

Power dividers are passive RF devices that divide the power of an input signal into multiple output signals with minimal losses. They are typically used in cellular, WiFi (2.4 and 5 GHz), and TETRA security band systems to distribute RF power between multiple transceiver antennas or radiating cables.

The most common type of power divider is the resistive divider. These dividers have two or more series resistors connected in parallel between output ports. The insertion loss for these resistive dividers is very low, but a portion of the power is dissipated in the internal resistors.

Resistive dividers are the simplest and least expensive type of power divider. However, they have some limitations. First, the maximum frequency range for these dividers is very limited, usually from DC to any frequency higher than 20 GHz (gigahertz).

Second, power dissipation within the network of resistors is very high. If you put a one-watt signal at port 1 and then send it through a 2-way resistive divider, it will result in two quarter-watt signals at ports 2 and 3 (down by -6 dB).

These disadvantages are the primary reason that many designers avoid using these devices for RF applications. Those designers who do choose to use resistive dividers must ensure that the device's power dissipation and impedance match are adequate for the application.

Another drawback of resistive dividers is that they lack isolation between output ports. This is an issue in a variety of RF applications, especially if the signals being split are not in phase.

In addition, the insertion loss and impedance of these devices can be problematic for a variety of different applications. This is why many designers prefer to use reactive dividers, which have a much higher impedance and better isolation between output ports.

Reactive dividers, like Wilkinson dividers, are also commonly used in RF applications. They have low insertion loss, and they are also very compact.

Another advantage of these dividers is that they can be used as combiners. This is because they often have the same components as a coupler, and they can be configured to work in both directions.

Couplers

The Directional Coupler is a key component in determining RF power distribution on your DAS.These specialized devices are the only way to achieve balanced and even RF power distribution. This is critical to achieving optimal throughput speeds for your DAS.

A directional coupler is a passive device that couples a defined amount of the electromagnetic power flowing in a transmission line to a port, enabling the signal to be used in another circuit. The most common form of a directional coupler is a transmission line design, but they are also available in waveguide designs.

RFS offers a wide variety of directional couplers and power dividers that can be used in many different applications. Directional couplers are the best way to combine the feeds to multiple antennas, and they can also help make up for the loss of signal in the feeder cables on higher floors of a building.

They are also great for monitoring and distributing signals across a large space. They are commonly used in broadband distributed antenna systems and provide excellent performance over a wide range of coupling values.

These directional couplers are available with a multitude of options, including two, three, and four ways to split a single feedline. They are designed to be compatible with a wide range of ICA aluminum and copper plenum-rated cables.

RF tappers, also known as signal tappers or power tappers, are an effective and economical solution for dividing a feedline among LTE, Tetra, private mobile radio (PMR), UMTS, or WiFi systems for indoor and outdoor DAS applications. They are available in a variety of ratios, from 2:1 to 1000:1, and operate in the 376 MHz to 6 GHz spectrum.

In-building and outdoor RF signal tappers are designed to split the input signal into two, three, or four separate outputs with a low-profile body. They are made to be tough and have a sealed design that doesn't use solder joints or O-rings to meet IP65 and IP67 installation requirements.

The Wilkinson power divider is a great choice for many RF applications where high output impedance and low insertion loss are required. They use two parallel quarter-wavelength transmission line transformers to isolate and split the input signal into output ports with matching impedances. The resulting circuit topology is one of the most effective power dividers on the market and provides several benefits, including high isolation, low insertion loss, and fast reconnection.

Combiners

Combiners are an optional process in mapReduce, and they reduce the data that's sent to reducers by aggregating the data from each mapper server. This isn't an optimization for every function, but it can make a big difference in the amount of data that gets passed to reducers when there are large amounts of data.

To be more specific, a combiner is a function that runs on each mapper server and outputs a tuple like "word" to the reducers on that server. The reducer then computes the "word count" value, and this number of key/value pairs is reduced before being passed to the next reducer server.

There are a couple of different types of combiners. One is a passive power divider, and the other is a directional couple.

Passive power dividers have symmetrical topologies, and they can be used to provide a balanced supply of RF signals from multiple sources to the receiver. They're also a great choice for phase matching between mixers and demodulators.

Another type of power divider is the reactive divider, which uses a transformer to split the signal into different ports. These are suited for high-power applications and have low insertion loss.

Using a reactive divider as a combiner can cut a system's cost and make it work better. They're available in 2, 3, and 4-way configurations with a wide range of connector options, including BNC, TNC, or SMA.

As with all dividers, there's a degree of loss in using a reactive power divider as a combiner. As a result, a designer must be careful when designing this type of component.

In addition, these power dividers are not as stable as hybrid power splitters. This means that they're often not the best option for long-term durability or use in a DAS application.

While they're not as popular as reactive dividers, hybrid power splitters are a good option for low-power distribution. They're also a good choice for RF and microwave applications and are available in many forms and factors.