Thanks for that most informative response, Avery, and also the link to Hans'
project.

Hopefully next week I'll get around to constructing my antenna (need to
visit a bike store and ask for busted rims this weekend... :-) ). From the
signal strengths you were quoting (100uV), it seems as though it's iffy
whether or not you'd see anything at all taking the output of the antenna
(with resonating capacitor) and feeding it directly to a spectrum analyzer
(since we're looking at, oh, -70 to -80dBm into 50 ohms, which is starting
to push the noise floor of at least one spectrum analyzer I have available
to use). If there's nothing visible at that point, however, hopefully after
a differential FET amplifier as you suggested the signal will be visible.
(I find it very reassuring to be able to see you actually have some signal
present at each point of a porject's development...)

---Joel