Hi shrubber,
The powered Terks and the like are really just variations on the T-shaped dipole wire that you already tried. I've used the Magnum Dynalab vertical 1/4-wave whip antenna and it worked quite well in a dense urban setting if you placed it near a window.
Even better is the Tivoli Audio PAL FM/AM portable that I reviewed for Sound&Vision magazine a year or so ago. It's also designed by the late Henry Kloss and I found it a bit more sensitive than the Kloss Model One. And you can swing around its telescoping antenna to "tune" in weak FM signals (and suppress interference) which is a distinct advantage over the Kloss Model 1.
The PAL also has an excellent AM tuner. Overall, I received more listenable reception to FM and AM with the PAL than using the Magnum Dynalab and the tuner in my receiver. Most of the internal FM tuner chips in receivers are mediocre at best and the AM sections are awful.
The little PAL is compact, so you can carry it around the house to listen to NPR, and I like its tone quality better than the Kloss Model One. Its internal rechargable battery lasts about 3 or 4 days and recharges in a few hours (you can still use the radio on the AC adapter while its charging).
Regards,
