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I read an article where they set up a incredibly high power, high gain WiFi antenna (https://hackaday.com/2016/10/15/a-lot-of-wifi-power-a-yagi-and-a-snipers-scope/).

He uses an RF amplifier in order to boost the power of his antenna, however in the comments of this article certain people claim that an RF amplifier only boosts the transmitting side, which means you'd be able to reach further away but not receive signals from further away. With research it seems that some amplifiers also allow you to receive signals from further away, could someone clarify this does an RF amplifier increase our range bidirectionally? And what type of available options are there out there?

As an example, if we'd be talking over the radio with a regular Yagi-Uda we might have a range of 30 miles, we'd both be able to hear (receive) people in those 30 miles and they'd be able to hear us (transmit).

But according to these comments with an RF amplifier and the same gear as above we might be able to be hear (receive) people in 30 miles, but they'd be able to hear us in 60 miles (transmit), I hope that makes sense.

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  • \$\begingroup\$ Bi-directional amplifiers are often used in a variety of systems. Tv communities distribution with wire uses these amplifiers widely. Even in the "optical" domain. This is possible by some "circulator" functions, widely used in Very high frequencies. But these functions can also be realized at very lower frequencies (phone line is one). \$\endgroup\$
    – Antonio51
    Commented Jan 30, 2022 at 12:24

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There can be more than one amplifier (and type of amplifier) in a wireless system, with different usages.

An output power amplifier which increases the output power, only increases the range in the transmitting direction. So in a bi-directional system if you only amplify the transmitter on one side, you won't get any extra range in the total system (unless the other end already has higher output power, that is).

But there are also amplifiers for reception, often known as LNA's (Low Noise Amplifier) which can be used on the receiver end to amplify the received signal going into the receiver.

So in case you use both an output power amplifier and an LNA on one end, you can definitively increase the range.

Also, as you mention antennas, a directional antenna will have just as much gain in both receiving and transmitting, so that will improve the range even if only used on one side.

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  • \$\begingroup\$ Are there any RF amplifiers which are bidirectional, they can both receive and transmit? Or would you recommend I get both an LNA and an output power amplifier and hook them up to an antenna? \$\endgroup\$
    – icyli2
    Commented Jan 30, 2022 at 10:58
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    \$\begingroup\$ I'm sure there are combined devices out there made for the task. It is not quite as simple as just connecting a power amp and an LNA to the antenna, as there must be some controlling of which amp is active etc. as they can't both always be active when the same antenna is used for both RX and TX. \$\endgroup\$
    – Klas-Kenny
    Commented Jan 30, 2022 at 11:06
  • \$\begingroup\$ Could you possibly guide me to some articles or books who've successfully implemented this before I'm struggling to find information about this subject? Thanks for the answer by the way it's a lot more clearer to me now. When you say the same antenna can't be used for RX and TX simultaneously, does this mean that radio communication never sends and receives at the same time? Even with WiFi for example, this never ever happens at the same time? Why is the design like this, if you'd be able to receive and send simultaneously wouldn't communication be a lot faster? \$\endgroup\$
    – icyli2
    Commented Jan 30, 2022 at 11:11
  • \$\begingroup\$ You could start with any book on wireless systems design. A single Wifi antenna never transmits and receives at the same time. You can't receive and transmit at the same frequency at once, as any received signal will drown in the transmitted signal. I think there are multi-channel WiFi technologies available that can actually do it, but that is using multiple antennas and frequencies. A Whole lot more could be said on that topic, but that would be too much for the comment section on SE. \$\endgroup\$
    – Klas-Kenny
    Commented Jan 30, 2022 at 11:28
  • \$\begingroup\$ Just looked at it a bit more, these concepts seem to be called half duplex, duplex... and are quite complex, I'm very new to radio communication and as my first project I'm trying to make very long links over WiFi and LTE but it seems like it'll take way longer to do that than I first imagined. Are there any devices which automatically could control which amplifier is active? So I could hook up a WiFi adapter to one of those, hook up an output and LNA amplifier to those and finally hook up the Yagi-Uda to those? \$\endgroup\$
    – icyli2
    Commented Jan 30, 2022 at 11:37
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Transmit receive modules (TR modules) used in high end radar systems have this sort of functionality - amplification on both transmit and receive. All the ones I've seen have separate devices (amplifiers) in the transmit path (High Power Amplifier, or HPA) and receive paths (LNA), with some way to switch between the paths (circulator, RF switch) between transmit and receive operation. In addition to the LNA and HPA (usually closest to the antenna) there may be an amplifier or two that are shared, depending on the architecture.

Do a Google search on "TR module" to get an idea what's involved here. Note that most TR modules have a lot more functionality that what you would need for your WiFi range extender.

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