As an alternative to professional wide band HF receivers, this old timer the Sony ICF-SW77 is a great performer. I acquired one who needed a minor repair and gave it test on the 80 meter band using a tuned wire antenna. The results were amazingly good. More on this receiver on Media Wave Circle.
Understanding HF propagation
Jari Perkiömäki, OH6BG 12 July 2012 Sappee, Pälkäne, Finland
translated and revised English presentation: For full article see this link.