Using the LP100 digital vector wattmeter, we measured the performance of two antenna systems at AA6E. The signal source was the Ten-Tec Orion operating at about 5 W output power.
80 / 30 meter dipole. This antenna is constructed as suggested by Joel Hallas in his QST articles on the Folded Skeleton Sleeve Dipole (May, October, and November, 2011). He did not offer an 80/30 option, but it was not too hard to model one with EZ-NEC that performed OK. A model with an 80 M wire (2*62.54 ft) and 30 M (2*21.65 ft) seemed to work well. When installed, the optimum lengths proved to be a percent or so longer. Good idea: cut longer and trim to length.
A 1:1 "Sevick inspired" balun matches 50 ohm coax. The antenna is supported at the feed point at about 40 feet elevation and by trees at the end points.
(The SWR values are on the right-hand scale.) The antenna is optimized for the CW end of 80 meters, centered at about 3650 kHz, with a 2:1 SWR bandwidth of about 200 kHz. With an antenna tuner, the whole 80 meter band is usable.
The percentage bandwidth of the 30 meter band is quite small, so the dipole's bandwidth is not an issue. However, the drive point impedance is on the low side, preventing us from achieving 1:1 SWR. Still, the antenna is probably usable without an additional tuner, since the SWR is only slightly over 2:1 across the band.
40 meter dipole. This is a conventional wire dipole with a center insulator balun fed with RG-213/U coax. It is suspended from trees at either end, making the elevation about 30-40 feet above ground.
The dipole is centered at about 7150 kHz and yields SWR < 1.9:1 across the entire band.