4 pagesV  « < 2 3 4 »  
 
REPLY
> 3G / WiFi antenna in the tablet | Talk, choose, do it yourself
ctich
Message#1
30.09.14, 16:36
Guru
*********
[offline]

Group: Moderators
Messages 14791
Check in: 04.05.09
Apple iPhone 7

Reputation:-  1720  +

3G / WiFi antenna in the tablet
3G antenna | Antenna for WI-FI | Antenna for LTE
In this topic, we discuss / ask all questions regarding 3G / WiFi antennas, their replacement, amplification, modification, and so on.



There is no curator in the subject. For questions about filling the caps, please contact the section moderators via the buttonPictureunder the messages to which you want to add links, or through QMS.

Post has been editedctich - 30.09.14, 16:46
plyrvt
Message#62
04.03.19, 18:18
Experienced
******
[online]

Group: Friendssavagemessiahzine.com
Messages 562
Check in: 09.11.17
Acer beTouch E100

Reputation:-  110  +

Nik4ok @ 02.22.19, 12:43*
I do not know why but old phones enhance the reception of the network signal. I suppose that at the very beginning of the development of cellular networks, when the signal was weak and unstable, the phones did so that they amplified the received signal.

The first phones (NMT, GSM) all had an identical antenna design: 1 whip antenna per frequency band 1 (NMT-450, GSM-900)

Later, the GSM-1800 band was added, but the antenna was vertical, a bit more complicated design with 2 resonances at 920 and 1800 MHz. At first she stuck out of the case, then she shortened it and hid it.

Later placed horizontally near the jaw (near the microphone).

Everything dramatically changed with the advent of smartphones:

- added the third range of UMTS-2100 (3G)
- WiFi has become an integral attribute (first 2.4 GHz, and later 2.4 + 5.4 GHz). Bluetooth also works on the same frequency as WiFi
- GPS receiver has become an integral attribute

Smartphones themselves became compact and stuffed to the eyeballs (there was no free internal space like there were buttons in them).

Then came the fashion for the all-metal case.

The latest “old school” phone was the iPhone 3.
At the top and bottom of the phone case was plastic, and under it were 3 antennas:
* one small printed GPS
* one printed 900/1800/2100 for 3 resonances
* One 2.4 GHz (WiFi + Bluetooth).

Further, this could not go, there was an urgent need for a radical increase in the number of antennas for more bands.
There was an urgent need to abandon plastic inserts into the body and make an all-metal body, for which it is not a shame to ask for $ 1000 +.

The iPhone 4 was the first to revolutionize antennas.
Attached Image


Modern zoo manufacturers and models - has a layout solution from the iPhone 4: the case only visually seems to be all-metal, there are almost invisible dielectric inserts in the top and bottom that separate 4 metal strips from the case (2 on top and 2 on the bottom).

An increase in the number of antennas is dictated by the 2 requirements of the time:
1) WiFi has become the de facto standard for MIMO 2x2 routers and subscribers with 2 antennas that support a chip rate of up to 300 Mbps (in the 40 MHz band). Even in inexpensive devices without MIMO support (only 150 Mbit), there is still an additional RX Diversity antenna (1T2R)

2) an integral part of LTE 4G is MIMO 2x2, and in LTE-Advanced even MIMO 4x4. All antennas for all bands already need 2 pieces each.

Most smartphones have this layout:
Attached Image

Attached Image


1) at the top is a horizontal antenna LTE-700/800/900, GSM / UMTS-900 with a working band of 690-960 MHz

2) on the side there is a vertical slot (slot) antenna 1700-2700 (GSM / LTE-1800, UMTS / LTE-2100, LTE-2300, LTE-2600). Antenna slot is an antenna-shaped hole in a large earth conductor. It is electrically equivalent to a piece of metal of the same shape as a hole, with the difference that the field is rotated 90 degrees, i.e. the vertical hole radiates a horizontally polarized wave.

3) nearby is the combined slot 2.4-5.4 GHz (WiFi)

4) on the opposite side, there is a duplicate 2.4-5.4 GHz combined antenna slot (WiFi) for MIMO, which has a third resonance at 1.6 GHz for receiving the GPS signal

5) below is the combined antenna 690-960 + 1700-2700 MHz for the implementation of LTE MIMO. In non-MIMO modems, it is used as RX Diversity (1T2R)

On the Low-band, these antennas practically emit nothing because of their small size; when simulating electric fields, almost all of the radiation falls on the earthen body of the device. For this reason, MIMO on low-band does not work (the isolation between the ports is almost zero).

Also, the low-band radiation efficiency is low - 25-40%.

Outdated GSM-900 stations operate more often with vertical polarization, therefore they receive little signal from smartphones with horizontal polarization.

In addition to the high CWS, a significant problem of these antennas is the unpredictable distortion of the radiation pattern. In some directions of space, the antenna amplifies, in some it weakens. Attenuation can reach -10 dBi
Attached Image


In addition, users can use all kinds of covers, including with a metal frame around the perimeter, which further aggravate coordination and distort the direction of radiation

With the certification of the iPhone XS Max for $ 2000 in FCC laboratories (US Frequency Supervision), the antenna efficiency when measured in an anechoic chamber decreased at some frequencies to 5% or less

Against the iPhone 4 there were lawsuits related to the poor performance of the antennas. Officially, Apple recognized the problem that it is associated with a mismatch of antennas with a certain contact with human hands. Officially offered to solve the problem by installing covers for $ 30

Some users suggested sticking tape on their own so as not to short the antenna on the case with hands, allegedly this adds 3 signal strength sticks to the UMTS-2100
Attached Image

In addition to the antenna design, the operating frequencies and output powers also changed:
* in GSM-900/1800, devices were allowed up to 10 Watts, in reality, the phones of the first half of the 2000s (such as Nokia 3310, 1100 and others) had up to 3 Watts in GSM-900 and up to 2 Watts in GSM-1800
* in modern 900/1800 phones, the maximum power is often limited to 1 or 2W (remember, GSM has been turned off in the US since 2013, besides serving roaming clients in border areas and some industrial devices in EDGE (alarms, terminals and other instrumentation)
* In the UMTS-2100, devices typically have 630 mW in voice mode and 200 mW for HSPA data transmission
* in LTE - 200 mW regardless of the range

Post has been editedplyrvt - 04.03.19, 18:39
rafailovgrad
Message#63
16.03.19, 00:16
Old resident
*******
[online]

Group: Friendssavagemessiahzine.com
Messages 763
Check in: 31.12.12
Xiaomi Redmi Note 4X Snapdragon 3/32

Reputation:-  36  +

Hello to all! Guys, when disassembling the tablet broke the antenna, now the mobile network is gone. I soldered from another 3g tablet, but when touching a plastic case, the network falls when the network just hangs. Tell me how to solve.
d.v.baker
Message#64
21.04.19, 10:38
Visitor
**
[offline]

Group: Active users
Messages 22
Check in: 23.02.19

Reputation:-  0  +

Hello. I ask for qualified help. He tore off the antenna of the antenna 3g of the irbis tx18 tablet at the very base. And 3 more strain. Soldered wire bridges. Catching unstable. Nepoymu what's the matter !!! Photo below.

Posted 04/21/2019 10:41 AM:

Catching the Internet is unstable.

Attached images
Attached Image
Attached Image
Attached Image
Attached Image
d.v.baker
Message#65
21.04.19, 10:45
Visitor
**
[offline]

Group: Active users
Messages 22
Check in: 23.02.19

Reputation:-  0  +

And one more question. Why wire is lead in two points of the base, making it like a loop in the base.
d.v.baker
Message#66
21.04.19, 12:06
Visitor
**
[offline]

Group: Active users
Messages 22
Check in: 23.02.19

Reputation:-  0  +

And one more question. Why and 3ji and Wi-Fi antennas on top are glued with metallized silver tape to the display?
d.v.baker
Message#67
21.04.19, 21:30
Visitor
**
[offline]

Group: Active users
Messages 22
Check in: 23.02.19

Reputation:-  0  +

More questions. What is the black paint on top of the antenna stickers? Ferrite?
d.v.baker
Message#68
24.04.19, 18:01
Visitor
**
[offline]

Group: Active users
Messages 22
Check in: 23.02.19

Reputation:-  0  +

Reconnected the antenna-worked! There was a short one when soldering. ;)

Posted 04/24/2019, 18:03:

All my questions above decided. In addition to black paint. What is it?

4 pagesV  « < 2 3 4 » 


 mobile version    Now: 04/29/19, 23:08