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View Full Version : DIY laptop internal wireless antennas


Stu
03-27-2008, 09:24 PM
I quite often get requests for wireless upgrades to laptops. In most cases simply adding a cardbus adapter does the trick, but some people want it all internally with no bits poking out.

In a lot of older laptops I see, there is usually a mini-PCI slot to add a WLAN card. If I'm lucky the antenna cables with be installed already, but most of the time they aren't. I have done a few DIY installs using mini-PCI antennas purchased off eBay, but it seems to be a pretty hit-and-miss affair. Sometimes the signal strength will be good, other times bad, and I can see no rhyme or reason why.

I'm begining to think there must a lot more to antenna positioning than meets the eye, but I have yet to find any good resources to teach myself.

I would appreciate your thoughts and experiences of this subject.

14049752
03-27-2008, 09:43 PM
I've done this quite a few times myself. Typically, in my opinion it's more trouble than it's worth.

When I install my own antennas, I always install them into the lcd housing on the top corners, away from any shielding if possible. (Obviously, for that, you have to use long wires.) I haven't had any trouble with any of them installed like that, usually the signal strength is within 5-10% of my macbook. The only systems I can think of that I haven't been able to do this are on IBMs because they tend to use the thin ribbon cable for video, and there isn't enough room to run the cables along side it.

Out of curiosity, where have you been installing the antennas when you do it?

MHCG
03-27-2008, 09:51 PM
Wave propagation is a science.

Are the antennas you're using multi-polarity? Ensuring that both antennas are of the same polarity (horizontal or vertical) can go a long way to ensuring you've got good signal strength. Of course you probably know metal attenuates the signal also.

Stu
03-28-2008, 09:52 PM
Out of curiosity, where have you been installing the antennas when you do it?

Typically I run them into the LCD housing, in the top corners. I get OKish results like this.

I've had less success positioning them in the base unit.

Stu
03-28-2008, 09:54 PM
Wave propagation is a science.

Are the antennas you're using multi-polarity? Ensuring that both antennas are of the same polarity (horizontal or vertical) can go a long way to ensuring you've got good signal strength. Of course you probably know metal attenuates the signal also.

No idea if they are multi-polarity or not. How would I find out?

MHCG
03-28-2008, 10:06 PM
what does the antenna element look like, is there more than one wire leading to the same element?

Are there one or two antennas? If there are two, they are probably single polarity. I would make sure that they are positioned 90 degrees from each other. In otherwords if one antenna is positioned like | position the other antenna like -

Make sure the antenna is mounted directly onto the plastic of the case not under the foil backing on the screen. It might be a good idea to cut the foil backing around the antenna element so it's not covered. on either side.

Stu
03-28-2008, 10:13 PM
What does the antenna element look like, is there more than one wire leading to the same element?

I believe they are what you would call the film type, with a single wire leading to each square of film. Very similar to the pic below:

http://www.myimagehosting.com/6903Is9sM-62725.pic

MHCG
03-28-2008, 10:25 PM
Read my post, I edited it.

Stu
03-28-2008, 10:40 PM
what does the antenna element look like, is there more than one wire leading to the same element?

Are there one or two antennas? If there are two, they are probably single polarity. I would make sure that they are positioned 90 degrees from each other. In otherwords if one antenna is positioned like | position the other antenna like -

Make sure the antenna is mounted directly onto the plastic of the case not under the foil backing on the screen. It might be a good idea to cut the foil backing around the antenna element so it's not covered. on either side.

Funny you should mention the 90 degree positioning because I've had better results when they are facing the same direction. Although I have observed the 90 degree angle in a few modern laptops recently and wondered what it was all about.

The foil cutting out I already tried, as I figured it may block the signal.

MHCG
03-28-2008, 11:08 PM
Funny you should mention the 90 degree positioning because I've had better results when they are facing the same direction.


That's probably just luck. The purpose of having the two antennas or a multi polarity antenna is so both horizontal and vertical polarities are available. Essentially it's so your WAP and laptop can work in any position. It just so happens your WAP had the same polarity. If you turn your WAP antenna 90 degrees, you'd lose probably 30 percent of your signal strength.