Jump to content

Need help with external antenna mod


Painkiller667
 Share

Recommended Posts

well, it doesnt seem too obvious to me, that it wouldnt work. Would you mind explaining? I mean there were many mods done like that, which did work. Here are some links for ralink chipsets being modded.

http://ronobvious.livejournal.com/296.html

http://www.oberkommando.org/asus_wl-167g/

http://www.xp11.com/g54/g54.htm

Keeping in mind that antennas are a special length depending on the frequency they are going to use. You're idea would kinda be like cutting the antenna in half and sticking on another one...

However I do admit I was not even close to being helpful and I'm sorry, what I should have said was. "Try and attach the antenna to the Start where the band meets the board or right before it enters a chip or the such" I hope that helps a bit more.

Link to comment
Share on other sites

I dont really understand what "Start where the band meets the board" you are talking about. Also, this might seem really stupid, and it probably is, but what if I connected a tv antenna to the chip? I supposed only if the frequency of the antenna is the same, the antenna would function for the wifi device. But how do I find out the frequency of any antenna, thats a really important question I really need to find an answer to. Thanks.

Link to comment
Share on other sites

I dont really understand what "Start where the band meets the board" you are talking about. Also, this might seem really stupid, and it probably is, but what if I connected a tv antenna to the chip? I supposed only if the frequency of the antenna is the same, the antenna would function for the wifi device. But how do I find out the frequency of any antenna, thats a really important question I really need to find an answer to. Thanks.

go read up on wifi and antennas and then come back...

Link to comment
Share on other sites

well, I read up, and found some great tuts for cantennas. So what I will do is I will probably make a cantenna and then wait for someone to finally have the answer to the mod for my exact chipset. About the frequency and the tv antenna being used for wifi, I still havent found out anything about that. Perhaps someone could link me to a site where different frequencies are defined for different objects, i.e. the tv antenna. As I have mentioned in one of my earlier posts, I have a huge tv antenna, on my roof, which looks like this: -|-|-|-|-|-

And I really would like to make good use of it. Anyone know how I can use it for wifi?

Link to comment
Share on other sites

If I had to guess, I'd say it's gonna have something to do with that copper square...

i must agree .. but it seems that it is connected to more than 2 ports on the PCB, therefore i probably isnt

Link to comment
Share on other sites

3726673745009a5a5f5bme8.jpg

don't blame me if it breaks, but at first glance i would try with a pigtail to bare wire

red = middle wire

blue = shielding

Using a tv antenna will not work, you have to get wire and an antenna that is made for the 2.4ghz frequency and is the right resistance (50 ohm iirc).

the copper square is just ground, its normally used for rf shielding for the chipset.

Link to comment
Share on other sites

thank you for the information, ill try it when I have a good antenna. What frequency is the tv antenna then, if I cannot use it. Maybe I could use the tv antenna with a 2.4 GHz cable? In any case, if that will not work either, then if i make a cantenna with a pigtail, and touch the pigtail to the appropriate connectors, will I see a sudden increase in signal right away?, is that how I find out if thats the right connector?

Link to comment
Share on other sites

"T.V." Frequencies:

Sub CATV Band - T7 - T13

7 - 58 Mhz

VHF Band - Ch. 2 - 13

54 - 216 Mhz

Low Band - VHF Ch. 2 - 6

59 - 88 Mhz

Mid Band - UHF Ch. 14 - 22

- UHF Ch. 95 - 99

121 - 174 Mhz

91 - 120 Mhz

High Band - VHF Ch. 7 - 13

175 - 216 Mhz

Super Band - CATV Ch. 23 - 36

216 - 300 Mhz

Hyper Band - CATV Ch. 37 - 62

300 - 456 Mhz

Ultra Band - CATV Ch. 63 - 158

457 - 1002 Mhz

UHF Band Ch.14 - 83 - CATV Ch. 63 - 158

70 - 1002 Mhz

Link to comment
Share on other sites

can you even solder? If you cant i wouldn't bother IMHO, just sell it and buy one with a connector or pigtail already attached or get some one who know whats they are doing.

At the end of the day you will just probably end up breaking it.

you cannot just "touch" the wire on the solder and expect any improvement.

Also what are you using this for? war driving or cracking yours/someone else's AP? if you were using it for war driving you should of bought an Orinoco classic gold/Orinoco usb. They are cheap enough, i just bought 2 for £10.

I suggest you do a lot of research and _then_ give it a shot.

Link to comment
Share on other sites

I have done research, and this is adapter is ideal for me. It cost me 18 bucks new, and my primary priority in looking for an adapter, is having it supported under linux with monitor mode and packet injection, which works. The secondary priority is now making a good antenna for it. I already have a parabolic dish reflector for it, but that only provides 10 dB better range for me. Therefore I want to have a cantenna which is more directional, allowing me to reach maximum possible signal if I want to access one specific ap at a time. Having a pigtail soldered to my adapter will allow me to use a cantenna for directional purposes, as well as being able to connect a biquad antenna to it in addition to the parabolic antenna for a more wardriving, open-to-more-aps-at-a-time purpose.

The reason I was wondering about if I can touch a pigtail to various possible connectors on my adapter to determine which connectors are to use for an antenna without soldering it every time, is because I do not know of the exact connectors to use to start with, so I will have to experiment with different ones, and if I will have to solder the pigtail to a different connector everytime, to determine which connectors to use will be a big pain for me. soooooooo it would be really helpful if someone knows what connectors to use for my specific adapter and they could tell me, for I dont want to solder too much on my adapter.

EDIT: BTW I found this:

http://www.ralinktech.com/ralink/data/RT2501_USBx5.pdf

the picture is not of my adapter, however my adapter does use the RT2571WF chipset and according to the bottom of the page those two little squares are marked 2.4GHz, and now if you look at the pics I provided, I also have the two little squares! lol great success! too bad I didnt prepare an antenna to test this out. I found a good n connector on ebay already, now I need to find a pretty long cable with minimal signal loss.

Link to comment
Share on other sites

Maybe I could use the tv antenna with a 2.4 GHz cable? In any case, if that will not work either, then if i make a cantenna with a pigtail, and touch the pigtail to the appropriate connectors, will I see a sudden increase in signal right away?, is that how I find out if thats the right connector?

I'm kind of on board with the "why bother" crowd, but I will explain for the sake of it.

Here's how it works (from someone who develops software defined radio):

The antenna: You cannot use an antenna for a TV because it is resonant for a different frequency bandwidth, and a horrible one at that. VHF broadcast is 55.25 MHz for channel 2, going up to 211.25 MHz for channel 13. UHF is 471.25 to 801.25 MHz. It would, theoretically work, because a 13 cm (the wavelength of 2.4 GHz) would definitely fit into that of a 6 meter (55.25 MHz) antenna, but it wouldn't likely be efficient. You are talking about bidirectional RF at the 2.4 GHz range. The antenna can be very small to work at that range, and most of the time, a blob of solder on the circuit board is good enough to obtain the RF signal, however susceptible to interference. Wireless cards are generally not shielded from stray signals (it looks like yours may), which is why the RF can be recepted on the board. We call that receiver ingress. So, what if it isn't an efficient antenna you ask? After a while, the impedence mismatch (in ohms, this case 50 ohms) can cause the transmitter to prematurely fail. There is no such thing as a 2.4GHz cable...just one in 50 ohms matched to the transciever and antenna's impedance. Not that it is a big deal for an extremely short length, but using a thin coax cable such as RG-8X for 2.4GHz is going to provide more problems than it is worth. I'd suggest RG-8 (Yes, different) for this kind of application if you are going to have decent length to the antenna.

The connector: N-type connectors are really bigger than you need for this application. Why not go with a much smaller SMA connector?

The circuit board:

1) The copper ring is most likely a grounding bar for the circuits it surrounds, not an antenna. This, along with (presumeably) a metal top, keeps out the stray RF signals.

2) The person who suggested the antenna location with the Red and Blue highlighting has it correct. (SordFish) Thats the antenna location. The dead giveaway is the 6 pin IC driving it. That appears to be a operational amplifier being used as a band pass filter configuration. If you have someone you can verify that with an o-scope, it might be worthwhile (You might be able to see it with a frequency dividing circuit, assuming you really want to do this. Thats pretty common connecting to the antenna. Or, I can tell you if you read me off the model number??

It's late, so if you see errors, take them with a grain of salt, please, and I am always up for corrections.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...