0

What would be a good unidirectional wifi transmitter receiver?

I want to be able to talk with a wifi router roughly 20 metres away through two walls, without letting the signal spread in the unnecessary directions.

2 Answers 2

1

Though you can buy commercial Yagi, parabolic and other design antennas, consider a cantenna, virtually free and far less obtrusive.

There are many descriptions, such as from Jacob Salmela and Instructables, but the key ingredients are a food can of appropriate dimension, a bit of coaxial cable and a connector suitable for your PC or phone.

Fine-tuning the antenna, both in aim it and in adjustment of the radiating element, is helpful. Use a real-time display of signal strength with applications such as wavemon on Linux or inSSIder for Windows.

1

without letting the signal spread in the unnecessary directions

you mostly want a directional or sector type of antenna, or a dish antenna. Step 1 is choosing directional or omnidirectional, you want some type of directional antenna.

https://www.signalboosters.com/blog/wifi-antenna-guide/

https://www.l-com.com/images/downloadables/white-papers/Selecting-the-Right-Wifi-Antenna-for-your-application.pdf

you would need a compatible type wifi card or desktop/rack sitting type of switch/router that offers a remote wired antenna connection via coax cable.

wifi6 or 802.11ax now runs in the 6ghz frequency range, 802.11ac in both the 2.4ghz and 5ghz spectrum, the old 802.11g in 2.4ghz only. So you would need to identify the type of wifi you are using and choose the antenna that supports your wifi's frequency or frequencies.

given the saturation of wifi everywhere, doing a directional antenna like you describe is a good thing, and pretty simple if it's between two simple and relatively small locations or rooms within a building. You want to look at the radiation pattern of the antenna and do basic trig and distance math to see if it will over coverage where you want it given the narrowness of its beam. As for dBi gain that you need I can't help other than say look for ones with higher numbers, and 20 meters is not far but it depends on the materials that need to be penetrated. And putting a directional antenna at location A but not at location B to talk back through the walls won't help, so you will need antennas at both locations in which case you could choose ones with a vary narrow beam but high gain which would reduce signal spread in unnecessary directions. A web search on such hardware you should quickly recognize credible products and sellers, some being sold on amazon/ebay do work but you take your chances on those ones.

A call/email to a credible seller or manufacturer of such antennas you would want to do and get their recommendation before buying, they will know all the questions that you need to answer and help guide you to buy something that suits your needs.

4
  • Why won't it help to have only one instead of two?
    – minseong
    Commented Dec 19, 2022 at 18:14
  • if wireless communication is needed between two points, obstructed by various material, an antenna at one point will be able to transmit strong enough to the other location but the other location may not be strong enough to transmit back. you need bidirectional communication to happen. It is possible that one very strong directional antenna only at one end can make the whole thing work but may be problematic. You would need a site survey to somewhat know, or you'll know in the end when it doesn't work with one antenna
    – ron
    Commented Dec 19, 2022 at 18:31
  • I was thinking that good directional receiver transmitter would be able to collect enough RF over an area that even if the signal is very weak, it can receive the remnants of what the other transmitter is transmitting reliably
    – minseong
    Commented Dec 19, 2022 at 18:33
  • yes that can happen, depending on the site. but it can be unreliable. which is why I mention find a reputable seller of such items who can answer that kind of question and recommend a given antenna. Ideally u want a directional antenna at both ends to ensure reliable communication, is all I'm getting at. If each antenna is $20 then no big deal but if each is $200 then yeah
    – ron
    Commented Dec 19, 2022 at 18:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.