Hack my PowerBook an antenna
June 19, 2006 5:37 AM   Subscribe

How might I attach my (broken) wi-fi antenna to my PowerBook, or to a (non existent) PCMCIA wireless card...?

I have an old Lucent wi-fi antenna, which (back in the early days of 802.11b) I used to attach to an external PCMCIA wi-fi card.

Nowadays I use an old PowerBook G4 and its internal wi-fi most of the time. But there's no way for me to attach the antenna for those times when I need it. The PowerBook has a PCMCIA slot - but I don't have the accompanying wi-fi card, nor do I have appropriate drivers.

To make things more complicated still, the little attachment at the end of the cable on the antenna has partly broken off.

Is there a way to hack something together? Should I buy another antenna? Can I buy the little metal attachment to replace the broken one on the antenna? Is there another wi-fi PCMCIA card or USB card I could buy which would work with the existing antenna?
posted by skylar to Computers & Internet (7 answers total)
Here is an example of someone doing something similar with a Dell laptop. So unless you feel comfortable taking a dremel to your powerbook, I would look into a usb wifi solution like this one.
posted by Lazlo Hollyfeld at 6:44 AM on June 19, 2006

Why? But if you have to, the antenna connector in your Mac is on the Airport card, which is internal (depending on the vintage of your PB, there could be a number of variables here). The built in antenna, which I believe runs around the screen bezel, is currently connected to that. The older TiBooks had notoriously poor wireless reception. Yes, you will need to drill holes in your machine.

Lazlo's USB solution won't work on a Mac. There are some external wireless solutions for the Mac, but nothing I know of that is designed to interface with an antenna.

For what it is also worth, word on the street is the new MacBook consumer models (the plastic ones) have awesome wireless reception. A friend told me it was almost uncanny how good it was, but then this has always been a somewhat weak aspect of Mac laptop design.
posted by fourcheesemac at 7:01 AM on June 19, 2006

Response by poster: Wi-fi in the garden is the reason. Also, sometimes they have wi-fi at Burning Man.

I notice that everyone else's Windows laptop always seems to have a far better range of wireless networks than my Mac laptop can see.
posted by skylar at 8:08 AM on June 19, 2006

Wifi reception on my 12" G4 powerbook has always been pretty good, at least as good as any PC Notebook. But if you want better reception you might have more luck with a USB wifi card that has a small fold-up antenna. USB is cheaper than PCMCIA and less hellish with respect to drivers.

As the above post says, this seems like a safer way to go than hacking your machine's antenna, which is probably located in your screen bezel.
posted by drmarcj at 10:52 AM on June 19, 2006

If the main reason is to get wireless in the garden, you might consider getting a wifi bridge.
posted by Lazlo Hollyfeld at 11:16 AM on June 19, 2006

Response by poster: Are there any wi-fi USB cards that allow me to attach an external antenna, or at least a giant antenna?

Also, with the wi-fi bridge solution, does that require for me to plug in a powered bridge somewhere? My garden is communal and a little distance away from my apartment, so while an antenna works I might not get all that much extra signal from the bridge than I would from where the wi-fi router is currently situated.

Unless the bridge doesn't have to be powered, in which case I could put it *in* the garden - furtively!
posted by skylar at 11:22 AM on June 19, 2006

I sense a fundamental assumption here that's false: "A bigger antenna gets me a better signal."

That's not necessarily the case. It turns out that an ideal antenna is half a wavelength of whatever frequency you're operating on. When it comes to something like AM radio, which is where a lot of people get their intuition from, the wavelength is 300 meters, so for any antenna of practical length, the signal strength increases pretty close to linearly proportional to the length of the antenna. (Because sin(X)~=X for X< (pi/4).)br>
If the antenna is less than half a wavelength, increasing its size increases signal strength. But once you reach half a wavelength, continuing to increase it decreases signal strength. When the antenna reaches 1 wavelength, it's essentially useless. Then when it reaches 1.5 wavelengths, it is again at the maximum. (Almost; leaving out some detailed issues having to do with capacitance and inductance and the fact that the speed of electrical signals in metal isn't infinite.)

802.11 operates at about 2.4 gigahertz, so the wavelength is 12.5 centimeters and the ideal antenna is 6.25 centimeters, about two and a half inches. Making the antenna larger will decrease its effectiveness. If it's 5 inches, it might as well not be there. At 7.5 inches it's again at the peak, almost.

Your Powerbook has 802.11 built into it. It also has the ideal 6.25 centimeter antenna built in. Why would you want to add more antenna and degrade the resulting signal strength? That's the reason there's no way to attach an external antenna: there's no reason to do so, because it cannot make the situation better but it can make it worse.

(The above discussion relates to omnidirectional "whip" antennas. As soon as you start talking about directional antennas such as dishes, everything's different.)
posted by Steven C. Den Beste at 12:06 PM on June 19, 2006

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