I've been interested in radar for so long. How do you get it to work at short range where you have nanoseconds to determine range? Well, I've been looking into what an RF module would be required to build a modular phased array setup. This has let me to believe how freaking expensive GHz class MMICs are. I've looked at Hittite's phase shifters. Analog and 4 to 6 bit digital. Nice parts... but somewhat out of my parts price range at around $100 each.
While I'd love to work on a 10GHz range design, I'm realizing that a 5GHz range unit is far more plausible with the advent of 802.11A/N and Wimax. Heck, TI's WLAN chipset might build the whole system at 2.4 and 5.2GHz with two chips and a few passives.
Research research research!