In my recent experiments I've obviously been experimenting with various different USB wireless adapters. One of them was the D-Link DWA-125 A3 (rt5370sta), another was the NetGear WNDA4100 (rt3573sta, you need to modify the driver to add support for the new chipset, http://ubuntuforums.org/showthread.php?t=1942689), while another was Jaycar's YN8306 (all Ralink chipets funnily enough with decent Linux support, http://www.ralinktech.com/en/04_support/support.php?sn=501). Clearly, after doing a lot of experimental work I've discovered a lot about antenna technology as well as the current state of wireless technology out there. One of the things I didn't realise is how drastic some of the differences could be between revisions of both adapter and chipset. My original purchase of the YN8306 seemed to be reasonable but the performance was nothing spectacular (Ralink 3070L). After discovering the USB port was somewhat loose (it was constantly losing grip of the cable) I exchanged it for another one but discovered something similar so this time I opened up the device and made some modifications (extra solder to bolster the strength of the USB port). While I was in there I noticed that the chipset had been upgraded to the Ralink 3072L. My thoughts regarding the Rev A were that it was good but didn't have the level of sensitivity that I thought it would. Rev B was a bit different though. Based on initial observations it may be at least 20% stronger with regards to sensitivity when compared to the Rev A and transfer rates were far less likely to fluctuate. A significantly better device overall.
With my recent incursions into antenna design I should probably extrapolate on what exactly I mean. I've torn apart anything and everything that I could possibly get my hands on and have even resorted to modifying television equipment in combination with broad range amplifiers to boost signal strength (I know it's not 'tuned' to the correct frequency but I just wanted to see what would happen.). What have I learnt? With enough imagination a lot of weird and wonderful things are possible. While hooking up my wireless adapter to the home television antenna (yes, the one on the roof) prooved to be an interesting exercise it only yielded slightly better results than having no antenna at all. A broad spectrum amplification device brought it up to slightly better than the originally included 5dBi antenna and forays into using antenna systems extracted from a dead router only yielded neglible benefits. A 16dBi antenna purchased during a local swap meet did result in a noticeable (though still small) gain though. Using a sieve (it's actually quite difficult to find suitable parabolic/spherical sized shapes in the house (unless you're willing to tear up potentially valuable goods such as headlamps). I had to go out and purchase a sieve for $2.80 at a local 'value store') only helped in certain configurations (I later found out an antenna from an old eMac was actually able to significantly boost the sensitivity of the DWA-125 A3 depending on it's polarity.) unless I switched to a more forgiving Gregorian Satellite Dish design (I used another smaller sieve and some elastic bands to replicate the design).
I even tried extremely crude Cantenna and Yagi style antenna designs (I'm waiting for an order to come in). The difference was that I made mine out of solf drink bottles with the bottom cut out wrapped with aluminium foil and also something I call 'Ruler-Yagi'. Basically, an antenna that was made out of a wooden ruler (boom), gold paperclips (it's suprising what you can find these days at Officeworks), blu-tack, and connected to a wireless adapter using alligator clips. There was a significant boost in signal (50%) when my 'Softenna' was directed properly and surprisingly there was an actual gain for 'Ruler-Yagi' but once again it was only minimal (10-20% signal sensitivity increase).
In the context of cyber-intelligence/operations it interests me to see what sort of antenna systems we could possibly pursue. There is a high likelihood that given the right materials high gain antennas could be embedded or inserted inside of suit cases or even other devices with connectivity being provided via cable (or hopefully) wireless. For example, a supposedly long life battery could be modified to provide a genuinely higher gain antenna provided space/cells were cleared from the internal cavity. Alignment could be facilitated by an internal lens/reflective camera system.