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Bi-Directional Amplifier vs. Distributed Antenna System Solutions

A German physicist invented the first parabolic reflector antenna in 1888. However, it was a Japanese inventor who created the first Distributed Antenna System in 1926.  You can consider these men to be the forebears of wireless technology.

Nevertheless, one of the greatest cons of wireless networks that still persists today is solidity. There is a way to fight a single antenna’s potential hiccups. We can either use more antennae or swap them out for an amplifier. But which strategy is best? As always, your friends at will help you decide.

We will explore the difference between Bi-directional amplifiers and distributed antenna systems. From this, you will understand which is better for your home and business.


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What is a Distributed Antenna System (DAS)?


Replacing one high-powered antenna with a group of low-powered ones is the basic idea of DAS.

However, this is not for energy-saving reasons. One antenna may not be enough to deliver signals through a building. As a result of the layout, interference may occur. This is where a DAS comes in.

How does a distributed antenna system work?

When people refer to DAS, they discuss it in terms of cellular signals.

Some buildings are not conducive to external cell phone signal coverage. A business will use a distributed antenna system to improve cell phone reception within a building. It will take exterior cell phone signals and disperse them through the interior. This will allow people inside to have network connections.

In addition, there are outside DAS systems with sector antennas that help spread 4G and 3G signals. Have you noticed how your cell phone connection dies as soon as you go through some tunnels but not others? We use DAS systems in tunnels and subways to help your phone keep a signal.

If you have a large house, you can use a DAS system of Wi-Fi antennas. This will ensure that your entire house has internet connections through Wi-Fi.


distributed antenna system


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What are the Types of DAS?

Types of DAS

Passive DAS


People refer to these as cellular signal amplifiers or cellular repeaters. This system uses an exterior donor antenna. The donor antenna sends a signal to an amplifier unit through a coaxial cable. But first, it checks the strength of the signal then it boosts it if needed. It finally feeds the interior broadcast antennas using splitters.

We usually place the donor antenna on the roof of a building. There are many types of donor antennas available. The most common types are directional or omnidirectional. Most businesses will use omnidirectional antennas for cell phone signals.

Cellular amplifiers also come in a range of sizes. Each size will be specific to the building’s dimensions. For larger buildings, you can employ multiple cellular signal amplifiers. You can cover almost any size building using passive DAS.

Active DAS


Active DAS works by passing a signal from a carrier to a digital conversion unit. The conversion unit will be in the building. The digital conversion unit converts the signal into an optical signal. It then passes it through fiber optic cables to a remote access unit (RAU).

The RAU converts the signal back into radio frequency (RF). It amplifies it and then distributes it through coaxial cables to broadcast antennas.

We use Active DAS in large areas with a lot of capacity. For instance, convention centers, airports, and stadiums.

Hybrid DAS


A hybrid DAS is very similar to an active DAS. However, it combines certain passive elements between remote power amplifiers and antennas. A typical hybrid DAS will combine RF signals from multiple carriers. Once that's done, it will convert them into digital signals.

It will then pass this signal through fiber optic cabling. After this process, it will change the signal back into analog once again. A power amplifier will then increase the signal. It then passes through a myriad of splitters, dividers, and coax cables until it reaches the broadcast antennas.

Hybrid DAS architecture tends to have more antennas per power amplifier than active DAS architecture. Also, it has less effective radiated power.

Distributed Antenna System--Digital DAS


In a digital DAS, the carrier transports the RF signals to the broadcast antennas digitally. In most cases, it simulcasts these signals.


Bi-Directional Amplifier (BDA) Solutions

A semi-alternative option to distributed antenna systems is bi-directional amplifiers.  We usually employ bi-directional amplifiers in two main situations: in two-way radio systems and cell phone networks. However, we cannot use cell phone signal BDAs instead of radio system BDAs.

A Cellular BDA works by intensifying and broadcasting cellular signals. Then they send them to and from cellular towers to your mobile device.


How Does a Bi-Directional Amplifier (BDA) System Work?


BDAs have two modes: transmit and receive. The BDA will intensify incoming signals. Once that's done, it will send them through your building while it is in receive mode. Then it will broadcast these signals using your building’s DAS.

The BDA will widen the scope of emitted signals when it is in transmit mode.

Therefore, BDAs can increase the network signal in your building. In the same way, a DAS system can.

There are two main types of BDA systems. We will cover them in the next section.


Differences Between Bi-Directional Amplifier Systems


Full Duplex Bi-Directional Amplifier: It can perform the transmit and receive function simultaneously. It places the transmit and receive signals in different channels or frequencies. Furthermore, full-duplex bi-directional amplifiers use filtration. This will ensure that the transmit and receive functions do not interfere with each other.

Half-duplex Bi-Directional Amplifier: Only performs one operation at a given time. Therefore, it will switch between transmit and receive mode. The half-duplex bi-directional amplifier selects the mode using a switch. It can use an intelligent biasing system similar to an RF amplifier.


Bi-Directional Amplifier vs. Distributed Antenna System



Distributed Antenna System Pros:


  • Gives you greater coverage;
  • Consumes less power than using a single antenna or high-powered bi-directional amplifier;
  • It may produce less noise than a BDA system;
  • Flexible



Distributed Antenna System-- Distributed Antenna System Cons:


  • Can be costly
  • Antennas and equipment may have a negative visual impact;



Bi-Directional Amplifier Pros:


  • You can incorporate them into DASs;
  • More cost-effective than DAS systems;
  • They are also very flexible;



Distributed Antenna System-- Bi-Directional Amplifier Cons:


  • May not be able to cover all the dead spots in a building;
  • May create more noise than a DAS if you employ more than one BDA;

Once again, despite the information in this section, BDAs and DASs do not have to work at odds with each other. You can incorporate a signal booster into a DAS. Incidentally, most companies utilize a few amplifiers along with their DAS antennas.

Nevertheless, we have not spoken much about the antennas that go into DASs. We will cover that in the next section.



Types of Antennas: Uni-directional and Bi-Directional


Most buildings or companies today will either use uni-directional or bi-directional antennas. But what is the difference?


Distributed Antenna System-- Bi-directional Antenna


A bi-directional antenna radiates signals in two directions.


Uni-directional Antenna


A uni-directional antenna will radiate a signal in a single direction.

While BDAs can send and/or receive signals in two directions, Uni-directional antennas can send stronger and more concentrated signals in one direction.

A good distributed antenna system can include a combination of BDAs and UDAs. You may even add an omnidirectional antenna or two.





Globally, we're moving towards more IoT integration. Connections in places where none existed before are more important than ever. This is why looking at a distributed antenna, or a signal boosting solution is crucial. In this guide, we explored the differences between DASs and BDA systems. Besides, we looked at what type of antennas you can add to your DAS. We hope that you have found this guide to be helpful. For more content and PCB-related content, please visit our blog. As always, thank you for reading.



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