I've been busy building my Arduino-based memory keyer (based on the work of K3NG) making antennas and doing some SDR work (with GnuRadio) in order to work some satellites.
I've built two quadrifilar helices, one for 2m and one for 70cm, and they both seem to work. The advantage of this particular antenna is that it is circularly polarized and nearly nondirectional. The circular polarization is good because the things I'm trying to do, repeaters, FM, and satellites, all need different polarization, and the required polarization for satellite work is unknown. The nondirectionality is a problem for receiving, so I'm considering my options. Right now, I think I want a set of short Yagi's that I can select with a remote switch. I think I can rig it up such that each one covers a portion of the sky and automatically switch between them. Of course, for transmitting, it's not a problem because I can always increase my power if I need to. I doubt I'll ever need to with low-orbit satellites.
I hope to have word on the SDR stuff soon, but the connector on the end of the 2m helix came off when I tried to unplug it from the diplexer and so I have to install a new one before I can test the system with off-the-air signals.