I didn't think it would be all that difficult for someone with better RF background than I have to make an educated guess of good placement. Is there no visitor here with that background, or is it a too-many-variables issue? Would a photo fill in a few? The Insert Image function here is disabled, but here's a URL to a photo:
This is a photo of the area behind the LCD panel, showing the existing antennas, aluminum shielding(?), and the new antenna coiled in the center. If the aluminum is present as RF shielding, why doesn't it interfere with the antennas? Is the square copper plane portion of each antenna not an "active" region that gathers signal? Is it only the zig-zag portion of each antenna, where the lead connects, that actively gathers signal? I ask that because if the aluminum is RF shielding, then it should be the areas not covered by it that would allow signal pickup, and the zig-zag portion of each antenna is in fact located so that it's just outside the shield. The Bluetooth antenna is also partially inserted underneath it, so that the whole of it is exposed to the outside, although that isn't true for the 802.11 antennas.
My best guess so far, without any more knowledgeable guidance, is that I need to lift up or cut away a portion of the aluminum shield and mount the third 802.11 antenna similar to the others, perhaps along the lower edge. Is the specific front-back orientation significant? I'd still appreciate an educated guess from someone else before I commit.
I couldn't wait any longer for a good Samaritan to appear. I replied upon my own limited judgment and installed the antenna. I don't yet know if it will enable the maximum bandwidth as I hoped.
Having seen all the unanswered requests for help and advice in this forum, it's apparent that Intel does not consider the people who post here to be customers at all, thus not worthy of any allocation of human resource. Considering the blunt "policy" rejection I received when I contacted Support directly, what I observe here isn't surprising. Anyone who dares to buy an aftermarket Intel WiFi interface card with the intention of *gasp* performing an unauthorized upgrade is more akin to a leper, pirate, or criminal than a customer.
A leper is precisely how I was treated by Support. That person was taught and trained to behave so callously; it is very unlikely it was that person's usual voluntary behavior. The decision-makers directing Intel's policies and employee training are directly responsible for that person's bad behavior. Putting an end to that unethical and irresponsible corporate behavior is one of the goals of the "Occupy" movement. I certainly hope that movement succeeds, so that no one else who needs help with a legally purchased Intel product is treated like a leper.