You can still see some of VK1OD's comments on the PA0RDT antenna here:http://groups.yahoo.com/neo/groups/600m/conversations/topics/8070http://www.youtube.com/watch?v=EWqJHTOijdE
I've built one of these from scratch. I used it in a second-floor apartment situation where it was impossible to ground the antenna properly. My experience, using it for HF listening, was that the antenna had a lot of noise caused by common mode currents. I understand that these common mode currents are all but impossible to stop if you don't ground the antenna; in particular, choking the feedline without proper grounding is insufficient because the choke impedance will always be less than the extremely high input impedance of the amplifier (which is necessary because the small whip is a high impedance antenna). See these links for some more details: http://active-antenna.eu/tech-docs/comm-filter-ftp-10.pdfhttp://www.qth.net/pipermail/lowfer/2003-September/010196.html
I gave up on the active whip antenna and instead used an active loop antenna (which, unlike the whip antenna, has a very low input impedance, making it easier to choke off common mode currents), the M0AYF active loop design based on 2 BJTs in a differential amplifier arrangement. It works surprisingly well, even inside of a concrete building.