Here are links to resources referenced in Daron’s presentation 12/7/22
From Daron N7HQR to Everyone 07:09 PM
this is the NVIS video: https://www.rohde-schwarz.com/us/knowledge-center/videos/understanding-near-vertical-incidence-skywave-nvis-video-detailpage_251220-908736.html
HF Propagation video: https://www.rohde-schwarz.com/us/knowledge-center/videos/understanding-hf-propagation-video-detailpage_251220-909312.html