Antenna issue
 

Hi! Had to register to post this message. So, are you guys familiar with the antenna of N800? One picture of the antenna can be found from the FCC documents, here's the link: https://gullfoss2.fcc.gov/prod/oet/f...ive_or_pdf=pdf

But here's my question and I hope that there is someone who understand this kind of antenna things: Do we have here only one antenna (dipole) or are those two antenna patterns for two different wireless systems (bluetooth and wlan)?
In my opinion it sounds quite stupid to use two separate antennas for the systems which operate in the same frequency... Or do we even have here antennas for the same frequencys (2.4 GHz)? And if not, it makes this whole thing quite interesting ;)

Re: Antenna issue
 

I dont know what it means, although I have a hypothesis.

You also can check the power emitted by the 4 devices (3 above 1 GHz, 1 under) in the same page of the FCC. 2 devices have output power undr 100 mW, one at 0,234 W? The other one we don't know.


That s why I asked 2 days ago for the specs of the wifi module.

Can someone help?

S

Re: Antenna issue
 

Can you give the link to that document and tell which page? Thx

Re: Antenna issue
 

Go to FFC webpage, go to

https://gullfoss2.fcc.gov/oetcf/eas/...ericSearch.cfm

enter

Grantee Code: LJP
Product Code: RX-34

Enter

On the page displayed, open the 3 form (view form), first left column . You will get the specs of the emitters (frequency, output power and class).

Re: Antenna issue
 

Well, last two pages seems to be quite ok (for me :)) because frequencies and transmission techniques match. 802.11b uses DSSS (one form of spread spectrum techniques) if I remember correctly and it's mentioned there, also the frequncy is 2.4G which is ok. Bluetooth also uses spread spectrum techniques and if I remember correctly, it's FHSS in BT case.

And there is a mention in the first case: "Low Power Transmitters below 1 GHz (except Spread Spectrum), Unintentional Radiators". That could be something related to AC voltage and charger, don't know. But the word "unintentional".

Re: Antenna issue
 

Yes however there are 2 lines in form with 100 mW output power units. Is it Wifi and BT?
And what is the unit with 0,234 W? in the same frequency range ( a bit more narrow) class "DTS - Digital Transmission System"

2,4 GHz is one frequency used by Wifi, Bluetooth and also Wimax (802.16 ) - source Wikipedia-

S

Re: Antenna issue
 

Hmm, actually quite interesting. One article says that the maximum transmission power for GSM900 is about 0,25W. And one of the FCC pages says 0,234W and the frequency is 2.4G. IMO the transmission power should be much lower when we are using that free 2.4G band. Hmm, do we have Wimax here? Actually the mobile version of Wimax is working from 2 GHz to several GHzs. And the transmission power (0.234W) could be something like that and there is no need for the line of sight component.

Re: Antenna issue
 

this is an hypothesis i thought since a week ago. but i m not educated in this field at all..
there is also a thread mentioning a hidden easter egg in this forum , which is not the fm radio. also so many people noticing the extraordinary sensitivity of the IT. i don't know.

Re: Antenna issue
 

From what I remember from reading the FCC papers those months ago, there is one single antenna used for both BT and wi-fi, in a multiplexing fashion.

Re: Antenna issue
 

i believe so, which is why i think the wifi gets dropped everytime a bluetooth device connects.

Re: Antenna issue
 

[QUOTE=TheSkyIsFalling;55390In my opinion it sounds quite stupid to use two separate antennas for the systems which operate in the same frequency... [/QUOTE]

Actually, it's somewhat clever. This approach is called "diversity reception," and depending on how it's implemented, is something as simple as selecting the antenna that has the stronger signal strength to something called "maximum ratio combining" where the two signals are summed together in a special way (this is actually the precursor of MIMO systems). Diversity reception has been around for decades -- and is pretty much ubiquitous in all laptops today for WiFi. It significantly improves the average signal strength a device receives, particularly when the devices is in motion: Just walking around often creates short-term fading in one antenna that can easily reduce its output to 1/100 or even 1/1000 or the typical signal strength; having a second antenna that's in a different location gives you a very good chance that at least one of the antennas is still getting a decent signal.

---Joel

Re: Antenna issue
 

confirmed by a chat I had with s-o inside Nokia about this subject in the N800

Re: Antenna issue
 

Oh yes, I'm aware of transmit/receive diversity and their advantages. And if in our case, N800, diversity is used, it would explain those two? antennas. But if the diversity is not used and we still have two antennas and BT/wifi uses only one of them, why there is two pieces? And what is the frequency of other one? Would be great if someone could calculate the frequency, I don't know what kind of effect the angle has, if it has.

Re: Antenna issue
 

So, There is a diversity combiner in N800?

Re: Antenna issue
 

Not sure. What I was told : "It is correct that there can be 2 antennas for the same "activity"* in our devices"

No comment at all on the fact that there is this 0,234 W emitter. Damn... However I was told by the same source before that the clue would be the output power.

* : I don't recall the exact term used. was it module?