New Antenna - Doublet or Loop Extension?

Even though my Twitter box says I've been QRT for several days, it lies. There have been a couple short stints on CW this week, but mainly I'm spending my radio time working on a new antenna. Nothing exotic this time, just a new doublet for my workshop station where my in-repair K2 and the Ten Tec Scout live.

I was also playing with an old Johnson Matchbox tuner and the AA-54 analyzer finding the correct settings for the 400 foot loop that is the only antenna down at that station these days.

I have gone back and forth several times in my mind whether to extend the loop with a new section that would raise the lower side of the loop about 20-30 feet or to put up a new long doublet that would be an average of about 70 feet above ground. I settled on the latter, and if later I want to absorb the doublet into the loop, most of the infrastructure work will have been done.

The line of the doublet hangs over a steep drop-off in terrain, probably about 100 feet at the deepest point. The choice of making the doublet 200 feet long was mostly a back of the envelope guess. I cut the wire to that length and Sean and I went to work placing the two pulleys, scrounging rope, and threading the wire through the "forest" of trees below the antenna line.

I later modeled that length, and even though I could go quite a bit longer (or shorter obviously) 4nec2 shows me that that length really is the best compromise for what i want to accomplish. In the plots below, due to the nearly E-W orientation of the wire, North is at the top and the strong lobes give me pretty good (theoretical) access overall to Europe, Australia, Japan, and South America, depending on the band. In the plots below the TO angle for 30M is 15 degrees, and 10 degrees for the plots of the higher bands.

As we pulled up the wire yesterday we had to do quite a bit of cutting of obstructing branches, sometimes whole trees (small ones, no more than 4 inches diamater), and we're still not quite done. I'll feed the antenna with homebrew open line for which I'd cached some plastic fence insulators some time ago for just such an occasion. The wire for the open line will be 14 gauge solid copper house wire. I haven't quite worked out how I'm going to interface the open line to the station, but I have several options to try there. Stay tuned (pun intended)!

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Thanks very much for your comment! 73, Casey


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