This Antenna design was one that I used about 4 years ago, it worked exceptionally well on 80m and 40m. The size of the antenna makes a Half wave length on 80 meters, and with the traps a half wave on 40m with a SWR (standing wave ratio) of 1:1-1.5 across both bands.
It worked well also on 20m with the use of an A.T.U (antenna tuning unit).
I made my version of this antenna using 3mm multi strand copper cable which I left covered by the PVC insulation.
The traps can either be home brewed using some 40mm diameter plastic drain pipe and winding wire around the pipe approximately 10 turns, then connected in line after the 10 metre lengths. Or the alternative is to purchase some commercially made 7.1 MHz traps, and fit them in line the same way.
The antenna can be fed with 50 ohm coax with a home brew balan or again a commercially purchased balan.
The wire lengths of the dipole are 2x 10 metres and 2x 6.7 metres as shown on the diagram above.
This antenna can be mounted quite low to the ground if you wish to produce a high angle of radiated signal which is good for distances of 0-1500 km.
For DX work a lower angle of radiated signal can be obtained by mounting the antenna 10 metres or more above the ground. The higher the better!
If you get chance to try this simple design, I am sure you will not be disappointed.
Good luck and hope to hear you on the bands.
de 2E0HTS 73