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NA7U's All-Band Doublet (80-10 Meters)

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Band Azimuth Plots on Great Circle Map
Band Elevation Plot
80 Meters - Your basic, average sky-warmer! I was surprised to see at least some gain at 30 degrees elevation though!
40 Meters - Even though the top is only up about 1/3 wl. for 40 it's starting to show some side nulls and fair gain at 25 degrees.
30 Meters - Looks a lot like 40 meters, but we're up 1/2 wl. here and the gain number is 3dB better. Not too shabby.
20 Meters - Now we're getting somewhere! Definitely some strong lobes and over 10 dBi gain. Unfortunately, just hitting a lot of water due to the orientation.
17 Meters - Hmmm, some side lobes starting to show up. The gain peaks here at 11 dBi. Probably not coincidentally, this seemed to be a natural resonance point for this antenna.
15 Meters - Wow, just all over the map, literally, with a commensurate drop in overall gain, only 6 dBi here.
12 Meters - Strong lobes in a quadrant pattern, very good gain, and finally covering Europe. 
10 Meters - Well, 10 meters is 10 meters, you expect to be able to work anything with a wet noodle. :)
SWR and Model Layout - Here's where theory meets reality. This was the first antenna modeling project I'd taken on and the software leaves a lot to be desired in terms of human interface, but after many, many (enjoyable) hours, I figured out how to model this doublet and confirmed that with an SWR plot matching my actual measurements.

Not perfect (esp. with respect to 80 meters, it is a lower SWR than shown), but very close. Using my auto-ATU, choke balun, and 4:1 voltage balun (optionally), I have no problem working all the bands plotted. Before this time I was skeptical about using open wire feeder, but now I'm sold! Low-loss and no RF problems at all.

Like most hams, I had to make do with the trees that someone else planted decades ago. Thus, the azimuthal orientation is not optimal, but I was fortunate to have enough horizontal space and trees with plenty of height. This antenna serves my very compact office station in the house, just my K2 and its power supply.