NVIS on 10,11 and 12 meter's??? Dipole

[Onelasttime]

Ok maybe I am just out of date but as a kid I grew up with the military using NVIS Dad was career Army and Infrantry. I was taught that NVIS was best for 1-8Mhz and was for bridging the gap between ground propagation and sky skywave propagation. I was always taught that as you went up in Freq. it became less and less viable. I even read research from about 1920-1940's where they used 10K+ watts and tested in various soil types and the ocean.

So the other day I was laughing at some youtube video's mostly out of the UK but a few where USA based talking about "better" skip DX with ones ground plane closer tot he Earth. I was taught that this is a wast as ground loss becasue your just heating up the ground. Same idea as to why mobiles antena systems have such high loss aka ground loss.

I have a dipole I made years ago for the rental property I was in before buying my current home. My current home is wrapped in steel siding not aluminum, not vinyl but thick heavy steel siding. My shingles are foil backed as well. I was going to use this in the attic until I could set up a tower but that will not work.

So I was wondering if anyone has tried NVIS with a dipole close to the earth with passive reflector or ground wires on the earth as well on 10,11 or 12 meter and what you thought?

What about some of these CB operators in the USA and UK of the opinion that a ground plane or even just a vertical dipole end feed or otherwise with out the ground plane like a GM, A99 or IM2000 close to the ground? It violates everything I was taught as a young man but well times change and yesterdays facts often become subject to modification latter on. I think the first thing I was taught as a kid about antennas was "Height Makes Might" the higher the better.

I did search google for NVIS and HF but did not find much related to my specific band and freq. range of interest it was mostly a review of what I was taught 30 year ago.

Also any particular favorite height and antenna types especially vertical. I had never thought about putting one antenna 50 foot or higher up and one insanely close to the ground what is it under 1/2 or under a 1/4 wave length above the ground???

Thanks for catching me up or even just pointing me in the direction of good information. It is preplexingly difficult to find anything relevant or concise as it relates to citizen band or even 10m on the internet. Since this topic is very much influenced by freq. once you get way above or way bellow the 30mhz cut off the relevance drops off quickly. Plus I am not running any external amplifier and most of the amateur accounts of using this form of propagation are always using 200 watts or more of power so again relevance. The other issue is using complex antenna systems that are huge often having 4 or more radials that are 75-150 feet in length and meant to be used by special forces on very low freq.'s and not to be permanently mounted but portable.

Again thanks for any help, information or personal observations. I have grown tired of lots of searching and lots of dead ends.

 

[vkrules]

Near vertical incidence skywave, or NVIS, is a skywave radio-wave propagation path that provides usable signals in the range betweengroundwave and conventional skywave distances—usually 30–400 miles (50–650 km). It is used for military and paramilitarycommunications, broadcasting,[1] especially in the tropics, and by radio amateurs. The radio waves travel near-vertically upwards into theionosphere, where they are refracted back down and can be received within a circular region up to 650 km from the transmitter.[2] If the frequency is too high (that is, above the critical frequency of the ionospheric F layer), refraction fails to occur and if it is too low, absorption in the ionospheric D layer may reduce the signal strength.

There is no fundamental difference between NVIS and conventional skywave propagation; the practical distinction arises solely from different desirable radiation patterns of the antennas (near vertical for NVIS, near horizontal for conventional long-range skywave propagation)

Wikipedia Does explain it. But not specific to 11m. If you read up on HF propagation in general it should help fill in a few of the details for you.

Basically if you are over the MUF (no skyway propagation) NVIS ,or short skip ,wont do you any good. Now with the current sunspot cycle being low on 11 we are at or over the MUF. Most of the time all you are going to hear is locals via directwave so the nvis dipole is going to be a disadvantage.

There are some openings but getting few and far between.

 

[Captain Kilowatt]

I know of people that pointed their large yagis and even Moonrakers straight up thinking that the more RF they could throw straight up into the ionosphere the better. Those were the same ones that couldn't even spell the word "ionosphere" much less understand what it was and how it works. LOL NVIS is a low band propagation mode. Not to say that in a very high MUF situation it won't happen but don't hold your breath for a while.

 

[Road Squawker]

NVIS on 11 meters??,... not a chance

75/80 meters, sure,..... perhaps as high as 60 meters

 

[vkrules]

It does occur. Highly unlikely for the next 6 years though!

 

[wavrider]

NVIS on 11???? Dunno to that, sometimes 27 mhz acts like 54 MHz in tropo thermal ducting ( ground wave is not correct term but commonly used to describe early morning comms on 11 meters)

It is true the comms during desert storm was very bad so the ops lowered their vert ant to horizontal positions and it did help for comms, probably due to polarization more than NVIS.

Try both ways at your QTH and see what works for you.

 

[Onelasttime]

Ok that is what I thought. that is in agreement with what I was taught. 1-8Mhz ideal with it falling off the higher in freq. you went with a sharp cut off absolutely at 30Mhz. Just thought it was faster to ask than waste 3 days researching this. I take anything I see on youtube that violates what I was taught years ago with a grain of salt. Thanks guys.

 

[Uncle Ronnie 336]

so im gonna bring this back because.....observations. i have an EDZ about 20' up flatside between trees. i have heard maine off of the end of the antenna (most flatside gain being broadside to the west coast) which tells me i am doing a little cloudburning because i skip right over them and most of the time land in hockey-france or the maritimes/europe. so this is really interesting stuff