Yet another antenna abomination.
I haven't done any real testing yet. It's sorta directional, shows some gain, and is cheap (about $9 in parts) to make.
Punch 1 3/8" dia hole in the bottom with a Greenlee or Walsco chassis punch. Do NOT try it with a rotary hole saw. It will grab and make a mess. Start with a 1/8" pilot hole. Enlarge to a 3/8" hole for the chassis punch. Then, use the 1 3/8" chassis punch.
In the hole, insert the 1" threaded to non-threaded PVC grey electrical adapters. Do NOT use the white PVC equivalents as they use a tapered, rather than straight, thread which is very difficult to crank tight. The washers are 1 1/2" to 1" reducing adapters. The flat bottom is a bit flimsy and should probably be reinforced with something (old CDROM disk?).
The center feed extension and handle are 1" PVC pipe. Any length will work. 3/4" pipe could have been used if the plastic case were removed from the USB device. However, 1" will work with other dongles.
The wireless USB dongle (or Wi-Spy) is connected to a USB extension cable and shoved into the pipe. Adjust the position so that it's close to the focus of the dish. It's NOT a parabola, so some trial and error will be needed. My current guess (probably wrong) puts the USB tip at 3" above the base.
A 1/2 wave (62mm) disk should probably be installed in front of the center pipe to block the direct path and to reflect some of the wasted RF back to the reflector. Next revision.