Modelling NVIS Antennas (are they really cloud-warmers?)

Thanks for exploring the issue. You are generally correct in most of your presentation. However do look up the relationship between DB vs S-Units. If you have 6 db increase in receive signal you have only ONE S-Unit. So 3 db is only 1/2 S-Unit. Plus lowering your dipole closer to the ground reduces local QRM from many sources so your usable signals do not require the same strength to heardand understand your contact as when your antenna is a half wavelength or more in the air. We do share the same openion about hams who's ego is dependent upon how many kilowatts they can put on the air. What is really annoying to me is that so many seem to turn DOWN their RF gain so they don't have to admit to hearing those of us that are happy to run 100 watts or less.

I use 5 watts with an FT 817nd and an end fed 1/2 wave ( for 40 meters) which is about 7 meters off the ground in between my house and the neighbour's house. It dips in the middle so is not quite above roof height. Here in VK3 I get out to VK 2, 4, 5 & 7 no problems with just 5 watts and always good signal reports on 40 meters day time. My best has been Spain but that was a tough contact. I have reached ZL too but I too like "local". That is, VK contacts and chasing SOTA & POTA and other activations. NVIS works very well. Today I was 5/7 to Southern Tasmania and that VK7 was 5/8. I was 5 watts and she was 100 watts activating a park. I am a foundation licence (aka, an F call). 73 de VK3 FIMD, Ian.

Thank you for sharing, very informative. I understood with the modeling used , this will help me to have more confidence on the low height antenna for QRP operation. I am doing a research/check on the QRP and best NVIS antenna to be used for local emergency communications.

Isn't NVIS considered 40-60-80 meters. I've never heard or read of NVIS being used on 20-meters. That's why you are getting the distances you claim. Try modeling a 40 or 80-meter NVIS antenna and things get real. This is what the military uses when the NVIS concept came to be. Try a 40-meter or 80-meter NVIS antenna at 16 feet. That's NVIS, not a 20-meters antenna at 16 feet. Try a 40-meter or 80-meter NVIS dipole. That's real NVIS.