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Adding internal wireless antennas to T23



Built-in wireless or not?

Lid differences Several models of the IBM T23 came with factory wireless already built into the system. Two internal WiFi antennas are located inside the lid near the top left and right corners. You can tell the difference between the non-WiFi models and the WiFi ones by looking along the sides of the lid (see picture at right). The T23 on top is the non-wireless model. It has a smooth, unbroken finish just above the hard disk bay. The T23 on the bottom is the wireless model. It has a small plastic "grating", behind which, sits the antennas. This was done because of the titanium composite lid blocks the microwave signals used by the 802.11a/b/g systems. This plastic panel provides a window for the radio signals to enter and exit the laptop.

Assuming you have a non-WiFi model and you wish to install some antennas, what does it take to do this upgrade? And why bother at all? Are there any drawbacks?

Pluses and minuses

There are several reasons why an internal wireless system is desirable. Generally, they center around these things: Some possible reasons why you wouldn't want to perform a wireless upgrade:

Laptop Disassembly

Bottom view showing screws to remove It's pretty easy to take the T23 apart as long as you take your time and have the Hardware Maintenance Manual handy. The only tools needed are a small Philips screwdriver and a possibly a small needle-nose pliers or tweezers. The picture to the right shows all of the screws on the bottom that need to be removed in order to take the keyboard, keyboard bezel and hinge cover off of the system.

Top view with keyboard removed This picture shows the top of the system after the keyboard has been removed. Three more screws need to be removed in order to free the keyboard bezel and hinge cover.

LCD bracket Two more screws to remove. This bracket covers the end of the LCD flex cable. It needs to be removed so that the antenna wire can go underneath it. This completes the disassembly of the bottom half. Now it's time to route the antenna wire.

Placement of first antenna

Mounting the antenna The first antenna is going to be mounted at the end of the battery bay, between the bay and outer edge of the laptop. This point was chosen as it is above the bottom half of the laptop, where presumably some more of the titanium composite is being used. It is up against the keyboard bezel which hopefully is just plain plastic. This area is what the eBay seller "wireless4laptop" diagrammed as the suggested mounting position for the T2x systems. It is also the same place where I had independently determined where the most effective spot is. Some suggestions have been made to place the antenna underneath the keyboard. As the bottom of the keyboard frame is metal, that's not a good place for the antenna. For best reception, the antenna needs to be as close as possible to the outer edge of the laptop, free from any metallic obstructions. Here the antenna has been positioned in the little nook besides the battery bay with the wire leading up towards the Ultrabay and then along side of it.

Routing the antenna cable The antenna wire is routed along the edge of the Ultrabay and then up behind it. The wire is placed underneath the LCD cable and finally shoved through the oval hole in the motherboard next to the fan.

Close up of LCD cable Here's a close up showing the way that the antenna lead is routed under the LCD cable and into the MiniPCI area.

Excess wire from first antenna The antenna I happened to have on hand for this experiment had a lead that is 32" long. You really only need about 22" if the antenna is placed where I've shown. I had to coil up the excess wire inside the MiniPCI area but fortunately it all fits inside. At this point I plugged in a Broadcom BCM94306 802.11b/g card and fired up the system. This card can be used with Network Stumbler and therefore can give me a good indication on how well the wireless system is operating. I was not too surprised that it does not work as well as a factory setup. Signal strength with the newly enabled wireless laptop was about -75db whereas my 2647-HNU indicates a -60db signal. That's actually not too bad when you consider that the embedded antenna is on the opposite side of the laptop from where my access point is. Being orientated horizontally as opposed to the vertical antennas on the access point doesn't help either. When I rotated the laptop 180 degrees (antenna in laptop was now closer to access point) AND put it on edge, the signal strength went up to -70db.

Seeing how I needed to replace a broken latch on the lid, I decided to try installing a second antenna inside the lid to see if it would help improve my coverage.

Second antenna - lid placement

LCD bezel screws to remove Getting into the lid is easy compared to the base of the laptop. Only three screws to remove and then it's a matter of prying the LCD bezel off of the lid. Four screws on the side of the lid hold the LCD panel. Since there are two different suppliers of panels, there's four screw holes on each side of the lid. Only two per side are actually used, however. Why am I trying to install an antenna inside a lid that doesn't have any plastic windows to "see" out of? Didn't I say earlier that the metal in the lid would interfere with the radio signal? Well, I thought that I might have discovered a placement which would work.

Ultraport You know that thin rubber plug at the top of the lid on the T2x systems? Yeah, the Ultraport. Well there's a HOLE in the lid that might allow a microwave signal through. Since I don't own any Ultraport device, nor am I planning to, I figured that this may be a way of getting better reception since the antenna would be at the highest point in the laptop. Yes, it's a tiny hole and yes it's still not orientated the "normal" way (horizontal, not vertical). But I thought, why not try. So here's a picture of the LCD panel after it has been dropped out of the lid and showing the ThinkLight (on the left) and the Ultraport (on the right). The end of the Ultraport ribbon cable is taped to a plastic frame.

Frameless Ultraport ribbon cable Simply pull the ribbon cable off the frame and tape over the contacts so that you don't get any strange USB errors.

Second antenna For this antenna placement I could not use the same one as in the base of the laptop since it was too large. I had another WiFi antenna which is significantly smaller and flatter so I taped it up behind the Ultraport opening. The rest of the wire was coiled and taped to the lid and then routed out the bottom of the lid near the left hinge cover.

Antenna lead out of lid Here's where the antenna lead comes out of the lid, gets threaded underneath the keyboard bezel and alongside the CPU heatsink to the hole in the motherboard. Plugged into the second antenna connector, the signal strength didn't change all that much, maybe a -2db improvement.

Final Analysis

Well, after all of that work how does a homebrew internal wireless system compare with the factory (HNU) version? It's a little bit worse and this is using the same Broadcom MiniPCI cards, same drivers and operating system so it's comparing "apples-to-apples". Is it better than a PCMCIA solution? I guess that depends upon the PCMCIA wireless card that's being used. The Netgear and D-Link cards that I use on my other 600X and T23 systems have a fairly poor signal on the opposite side of the house from my access point. The newly-enabled wireless T23 that I updated today has almost the same performance as those PCMCIA cards. It tends to drop the signal more often. However, my 2647-HNU beats all of them in signal strength and distance.

wireless4laptop suggests the placement for the second antenna to be next to the heatsink/fan assembly. I don't like this for two reasons: a) it's HOT there! and b) a huge hunk of metal which will cause a blind spot towards the back of the laptop. I had hoped that the small opening at the top of the lid would be enough to permit the radio signals to get to the antenna. I may have to play around with the positioning of the antenna to see if it can be improved, but for now, I'm happy with the new system.



Raymond Kawakami
San Jose, CA
E-Mail: r k a w a k a m i AT y a h o o DOT COM

Copyright 2006
Version 1.0 - Released February 11, 2007

All photos were taken by me using a Canon A10 camera and prepared for web posting using Paint Shop Pro 7. You have permission to link to this page but not to claim it as your own.