Why are 2.4Ghz antennas soldered on vs. 5Ghz clipped on?

Thread Starter

MikeA

Joined Jan 20, 2013
253
I put in an external antenna jack into my WFi router and was wondering why did they solder on the 2.4G antenna and used a mini U.FL connector for the 5G band?

There was one horizontal oriented PCB antenna and one vertical oriented for each band. Does it mean there actually 4 real transmitters inside?
 

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Delta prime

Joined Nov 15, 2019
809
Hello there :)
wondering why did they solder on the 2.4G antenna and used a mini U.FL connector for the 5G band?
In production of a product it's all about cost and efficiency with design as well but it would seem that the 2.4 GHz antenna connection was wave soldered a faster process than hand soldering and you don't have to pay anybody to do it. The Hirosie U.FL connectors are commonly used in applications where space is of critical concern, embedded systems PCI cards laptops and the like.
There was one horizontal oriented PCB antenna and one vertical oriented for each band. Does it mean there actually 4 real transmitters inside?
No does not mean there are four real transmitters inside. They use it because the antennas are polarized one horizontally polarized the other vertically polarized. A lot of times you will see two antennas on the back of the unit I call them rubber duckies also known as helical antennas like a spiral these antennas are omnidirectional meaning the radiate or transmit and receive in all directions, as opposed to a vertically polarized antenna or a horizontally polarized antenna that's one of the reasons why there's dead zones or dead spots because of the polarization, in short with omnidirectional antennas there's no need for orientation to get the best reception and they're dual band antennas they work on both 2.4 and 5 gigs and the access point itself actually chooses the antenna to use whichever one has the best signal strength.:)
 

Thread Starter

MikeA

Joined Jan 20, 2013
253
In production of a product it's all about cost and efficiency with design as well but it would seem that the 2.4 GHz antenna connection was wave soldered a faster process than hand soldering and you don't have to pay anybody to do it.
I'm not sure you looked at my attach picture. The sockets for the 5.8Ghz antennas were wave soldered. The antenna leads for the 2.4Ghz antennas were hand soldered. This is on the same PCB, an inch away from each other. That's what I was curious about. Why they made the choice to do it two completely different ways on the same PCB.

No does not mean there are four real transmitters inside.
Why not? Does it mean that 2 antennas a connected to 1 transmitter?

A lot of times you will see two antennas on the back of the unit I call them rubber duckies also known as helical antennas like a spiral these antennas are omnidirectional meaning the radiate or transmit and receive in all directions
A rubber ducky radiates in a donut shaped pattern. The reason I suspect my router has both a vertical and horizontal oriented antennas for both bands (4 total) is to get better coverage across multiple floors of a house. Since a donut shape would only work well on one floor.
 

Thread Starter

MikeA

Joined Jan 20, 2013
253
Interestingly enough, on the FCC website, from the report when this router was tested, they have a picture showing that the PCB had 4 antenna sockets (2 for 2G and 2 for 5G), yet they STILL soldered on the 2.4Ghz antennas.

fcc.png
 

vanergr

Joined Nov 23, 2020
3
I will point out that the 5G antennas are soldered on their individual pcb's. So I would guess it has to do with ease of assembly. The 2.4G I would guess that the connector comes pre assembled and in order to reduce connector noise. Also this way they can reduce manufacturing defects by soldering on antenna and plugging in the other, both from mixing bands and not pushed on properly connectors. That has been my experience at least.
 

Delta prime

Joined Nov 15, 2019
809
Hello there again :) your router can look like a porcupine riddled with antennas think less about the number of antennas and more about added functionality. Specs like MIMO and MU-MIMO increase a router’s capacity to transmit and receive data, which makes your network faster.
the software that drives the antennas is what really matters The router automatically manages your WiFi connections, performing load balancing across the two 5 GHz and 5.8Ghz radios along with the one 2.4 GHz radio for a total of three transmit receive radios. This additional WiFi bandwidth combined with the intelligence to segregate traffic based on WiFi speed and load balancing provides the best performance ..The 2.4 GHz band has 11 channels to choose from. But of these 11 channels, only 3 are non-overlapping. So basically you have 3 solid channels to choose from. But the 5 GHz has more channels. It has 25 non-overlapping channels. Some other differences between the 2.4 and 5 GHz band is the speed and the range that they cover. The 2.4 GHz band transmits data at a slower speed than the 5 GHz. But it does have a longer range than the 5 GHz. The 5 GHz band transmits data at a faster speed than a 2.4. But it has a shorter range. The 5 GHz has a shorter range because it has a higher frequency and higher frequencies have a harder time penetrating solid objects such as floors and walls in a building.
 
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Delta prime

Joined Nov 15, 2019
809
Why not? Does it mean that 2 antennas a connected to 1 transmitter?
Normally you have two antennas one for transmit one for receive but there is a thing called a combiner one antenna for both transmit and receive but that's a totally different thread.
 

Phil-S

Joined Dec 4, 2015
188
All the 2.4-GHz modules I've ever worked with, XBee mainly, come with chip, wire, SMA or UFL versions.
The UFL types are all clip on, by which I mean the antenna can be clipped on or unclipped.
Personal preference is UFL to RPSMA.
 

du00000001

Joined Nov 10, 2020
40
Back to the initial question:
The reason for the 2.4GHz lines being soldered could be that the U.Fl connectorswon't pass through the nut of the antenna connector (which is screwed to the housing's wall).
Consider the mounting sequence:
1. Fasten the connectors (cable already attached) to the housing (feeding the cable through the nut
2. Insert the PCB into the housing.
3. Attach the cable to the PCB.
...
You just won't want to prepare the cable for crimping the U.Fl plug if you can simply solder the cable to the PCB.

The 5 GHz antennae are different: they come as a piece of PCB with a cable soldered to the PCB that most likely already help a U.Fl plug crimped to it. Now it's just about inserting these antenna PCBs into their mounting positions and plugging them in.

BTW: there's quite some manual work involved: even crimping the U.Fl plugs to the cable might be just semi-automatic. And soldering the cable to the wall.mount connectors (for 2.4 GHz) will not be different.The shrink sleeve alone is tale-telling!
 

Phil-S

Joined Dec 4, 2015
188
No,
du00000001
I'm afraid you're wrong.
I've used many UFL to RPSMA and antenna to match.
There is no problem at all passing the UFL connector through the SMA nuts.
I don't bother crimping them because the made up cables are cheap enough.
Microchip and RF Solutions do them as stock items.
 

PadMasterson

Joined Jan 19, 2021
26
It could also be that the connectors are for final test at the factory? Trying to probe something like that can be difficult to start with and having a connector in place make snapping a correct impedance probe/cable to the board for test... Soldering the other may be as was stated above and just simpler to do. There is always going to be some hands on work for things like these so it's a pick the lowest cost process and go with it.
 
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