I bought a wifi repeater. It has 4 antennas. I want to use aluminium foil to extend the range of wifi repeater. What shape should i use? I have been experimenting a little bit.

 

How do You know that You have a problem with poor reception ? Or, are You guessing ?

Please describe in detail exactly what You are trying to accomplish.

If You had a single Antenna, or maybe 2 Antennas,
there would be several options that are common and very likely to make an improvement,
but a 4-Antenna-System is already fairly sophisticated,
and You would be just as likely to reduce the range as to improve it.

How You align the Antennas vs each other,
and how the group is "aimed" relative to the other Transceivers in the House,
could make all the difference.

It also makes a difference whether the System is using High-Frequency-ranges or Low-Frequency-ranges.
Some Systems use both at the same time.
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.
.

 

I am trying to extend the range with aluminium foil, that is what i am trying to accomplish.

 

Is this in an average House ?
House to Garage ?
House to House ?
1, 2, 3-Stories House ?
Commercial-Office-Building ?
What type of Construction ?
What are the distances involved ?
Every single detail makes a difference !!!
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.
.

 

I am trying to extended the wifi signal any distance, so what shape should i use? This is a 1 story house. This is an average house, i think. This not an office building.

 

I am trying to extend the range with aluminium foil, that is what i am trying to accomplish.

The antennas on your router are already tuned. Adding to their length will de-tune them. You might be able to extend the range my making a parabolic reflector "behind" the antenna, though I doubt it will work. The other problem is that these routers are tested with the antennas attached at the factory and modifying them would, in most jurisdictions result in an illegal transmitter.

You can buy WIFI repeaters to expand your coverage legally.
https://www.ebay.com/sch/i.html?_nkw=wifi+repeater&_sacat=0&_from=R40&_trksid=p4432023.m570.l1313

They are pretty inexpensive too.

 

The antennas on your router are already tuned. Adding to their length will de-tune them. You might be able to extend the range my making a parabolic reflector "behind" the antenna, though I doubt it will work. The other problem is that these routers are tested with the antennas attached at the factory and modifying them would, in most jurisdictions result in an illegal transmitter.

You can buy WIFI repeaters to expand your coverage legally.
https://www.ebay.com/sch/i.html?_nkw=wifi+repeater&_sacat=0&_from=R40&_trksid=p4432023.m570.l1313

They are pretty inexpensive too.

What does tuned mean?

 

It means that it works efficiently at one particular frequency.

This might give you a clear idea of the concept.:
https://www.onallbands.com/tuning-your-dipole-antenna-installation/