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I've a LTE router with WiFi, it switches automatically between LTE bands 3, 5 and 40, depending on the respective signal quality.

I want to improve the band 40 reception. So I think the easiest option is to remove the band 3 and 5 antennas. As the propitiatory firmware provides no interface to switch or lock a specific band.

The main problem is identifying the correct antennas to remove. The device has 4 patch antennas, printed on yellow mylar films. All of them looks similar to me!

So how can I identify the band 3/5 antennas ?

The WiFi chip is RTL8192EU, which is capable of 2T2R MIMO, so is it possible there's 2 antenna for WiFi? I can provide internal pictures if needed.

Device is made by Pegasus Telecom, subsidiary of Haier.

Pictures, main board.LTE router

Antenna on topenter image description here

Antanna on left and right, seems like inverted F monopole.enter image description here

Antenna on bottomenter image description here

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closed as off-topic by Chris Stratton, Finbarr, PeterJ, RoyC, Bence Kaulics Mar 9 '18 at 8:16

This question appears to be off-topic. The users who voted to close gave these specific reasons:

  • "Questions on the repair of consumer electronics, appliances, or other devices must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design of the device being repaired. See also: Is asking on how to fix a faulty circuit on topic?" – Chris Stratton, Bence Kaulics
  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Finbarr, PeterJ, RoyC
If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ place some aluminium foil over the antennas and see what harms the band 40 operation \$\endgroup\$ – Jasen Nov 4 '17 at 8:04
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    \$\begingroup\$ @τεκ, if I remove the antennas for band 3 and 5, then there will be no(or very weak) reception on those bands, thus practically locking the it to band 40. \$\endgroup\$ – Arnab Nov 4 '17 at 11:31
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    \$\begingroup\$ I'm voting to close this question because questions about the use of electronic devices uninformed by engineering design detail have been ruled to be off-topic here. \$\endgroup\$ – Chris Stratton Nov 5 '17 at 3:11
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    \$\begingroup\$ I doubt that you router has seperate antennas for each of the LTE channels. Most likely, it receives all the channels over the same antenna(s.) It might have multiple LTE antennas, but still not have an antenna per channel. \$\endgroup\$ – JRE Nov 7 '17 at 6:36
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    \$\begingroup\$ the left and right do not look like they are the same. i suspect that the smaller one may actually be the one you want \$\endgroup\$ – jsotola Nov 12 '17 at 0:00
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Based on the wavelength-to-antenna ratio, it can be assumed that the largest antenna is for the 5 band (850 MHz), the left antenna is for wifi (2,400 MHz), right is for the 40 band (2300 MHz) and the lower is for band 3 (1800 MHz). UPD: as written on the antenna, abbreviation RJ-PRA and RJ-DIV mean that the antenna is intended for mobile communication (main antennas). And with the reduction of RJ-WFA (maybe left right side antennas, you need to check) and RJ-WFB, it's a wifi antenna. (here is the info about antennas https://www.eximpulse.com/import-product-I-phone-6.htm?tpages=35585&page=3596)

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The LTE Band 40 is 2300 and Band 3, 5 at 1800, 850. This means that the shortest features on the LTE antenna/s will be what you want to keep. You may be able to cut the longer 850 MHz dipole parts off without much affecting the 1800/2300 sections if they are on a single foil section.

One LTE antenna may share band 40 with one of the longer antennas.

There are likely two WiFi antennas for diversity, they are also likely dual band at 2400 and 5000 MHz on each antenna so these are more likely the two smaller side antennas.

You may be able to replace the LTE antennas with a simple 1/4 wavelength element selected for 2300 MHz. To maintain a similar band coverage a wider (like the flat conductors they have used) or larger diameter element (screen connection of a thin co-ax cable). Trimming it to length without network analyser gear will be challenging.

Here is an interesting paper with a lot of theory and some history on LTE antennas.

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You really cannot distinguish them most of the time as many antennas can be use for both LTE and 2.4 GHz Wlan, and they look similar. The 5 GHz wlan antenna could be shorter.

If you look at the datasheet, some LTE and Wlan antenna has similar frequency response in the 800 - 3000 MHz band.

That is because a lot of antenna vendor choose to design it such that they can be use for cellular and wlan.

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