If anybody is interested, I have an EZNEC EZ file for the D2T antenna. LB put this together for me back in 2006 and I'm just revisiting it now as perhaps a worthwhile option for on the beach, vertically orientated between a couple of fishing poles. It seems to be a viable way to cover a wide range of bands with one antenna.
Yes, I know the antenna has a resistor in one section, and some may see this as too lossy, but as pointed out by G3LDO:
"The important thing to remember is that the D2T antenna is a high impedance antenna, so all other losses are small. If you consider the case of a small trapped mini-beam the radiation resistance is very low. For a given effective radiated power the current through the elements must be very high. This means that the resistance of the material used to make up the elements is significant : in effect with a low impedance antenna you have a built-in series resistor in the elements. The D2T is an ideal antenna for someone who has a restricted size location and has to install an antenna that does not require adjustment." (ref http://antenna.it/commercial/radiotoday.htm)
Is there any way of posting the EZ file here, or do I need to upload it somewhere and post a link to it?