Are the WiFi and Bluetooth antennas interchangable???

[VFR_firefly]

I'm working on a reflow and a rebuild of a couple of old T4x's that I want to combine into one good one. One has a bad monitor and I got stupid and flipped the microswitch off of the LCD connector so I have to swap out the cables (of course I didn't break the microswitch off of the cracked screen assembly)

SO, while I've got the LCD apart I figured I'd put in a bluetooth antenna since one screen is a T40 and the other is a T41 neither have bluetooth antennas "ready." Can I just use one of the extra wifi wires instead? Will it work? I don't care if it isn't optimal but it has to be better than nothing. Ordering one off of ebay will take forever and I'd like to get this machine together this weekend after I try my reflow (I've got 2 motherboards so I figure I'll get lucky at least one of the times.

I know the frequencies of bluetooth and WiFi are different and should theoretically have different length antennas but how accurate do they have to be?

I tried searching for an answer but couldn't find anything even remotely close to an answer to this. I can't be the only one who has thought of this can I?

[Johan]

Although I have never tried to swap the Main and the AUX WLAN/Bluetooth antennas (in any laptop), I believe that that may be possible with no or little difference in performance... for reasons discussed in the threads Bluetooth antenna? and Have I BT antenna in my system? (and the links therein).

More experienced ThinkPad-users may no doubt confirm (or the opposite!) this belief.

Johan

[VFR_firefly]

I've been looking at the antenna kits on ebay and the manual a little bit more and it looks like the antenna end is a little different for all 3 antennas. The BT antenna looks like just a piece of metal while the other two look like they have PCB's on them at the top and then a piece of wire after that.

I'm thinking I might just have to figure out the frequency of BT, dig out my ham radio books and figure out how long an antenna should be at that frequency and just fabricate my own antenna at the end of that tiny, tiny, tiny little coax.

How good does a BT antenna have to be anyhow? It's only got to travel 30M right? If I can get it to work with stuff at 3M I'll be happy.

[VFR_firefly]

Heck, it looks like it is an itty-bitty J-pole antenna!

I don't have any copper tubing that little (only hams would get that joke .... .. .... ..)

[Johan]

Heck, it looks like it is an itty-bitty J-pole antenna!

I don't have any copper tubing that little (only hams would get that joke .... .. .... ..)

Well, they may look a bit like a J-pole, but in microwave terms these antennas are most often labeled "inverted-F" (try Google for "inverted-F and WLAN "and a bunch of hits will show up!). You may also try serac on eBay after "thinkpad wifi antenna" and you'll see how they look --> such as these.

...-/-.--//--.../...--//-.././/---/--../.----/./-.--/-..-/



Johan

[sjthinkpader]

Both WiFi and BT use the same frequency band, 2.4Ghz. The WiFi card do need both antennae for antennae diversity function.

The BT antenna is not as critical since the BT device is typically pretty close. I have used the Hitachi Cable antennae with short lead on both BT and WiFi with good results. You can just leave the BT antenna under the KB and it will work fine.