Tropospheric Propagation

VHF propagation beyond that of line-of-sight occurs by using the troposphere, the Ionosphere, or an obstacle such as the moon or a building.

There are three types of tropospheric propagation, or “tropo”, which take signals a significant distance beyond the horizon:

1. Enhanced tropospheric refraction occurs when there is a significant increase above the normal value of the refractive index in the atmosphere.

2. Tropospheric ducting occurs when radio waves are trapped within channels bounded by sharp changes in refractive index and…

3. Tropospheric scattering, which arises from small-scale variations in the refractive index.

These modes occur almost exclusively in the lowest few kilometres of the troposphere where the air density and water-vapour content are greatest.

It’s also worth noting that the refractive index decreases with height.

0:00 | Introduction
0:46 | The troposphere
1:20 | Refraction
1:54 | The most common VHF and UHF propagation
2:11 | The 3 types of Tropospheric Propagation
3:05 | Enhanced Tropospheric Refraction
4:00 | Tropospheric Ducting
4:12 | Surface Ducts
5:28 | Elevated Ducts
6:33 | Tropospheric Scatter
7:48 | Radiation Inversions
8:19 | Subsidence Inversions
10:20 | Aerological charts (BoM)
10:52 | Propagation prediction charts
11:12 | VKspotter

[davidxbeats]

These are the highest quality videos explaining propagation I've ever seen! Great work!!! Thank You!!! 73!

[Uberhood]

A very good and thorough explanation with some great imagery! Thanks for sharing, 73!

[alimuqaibel]

The best video I found about ducting effects. Thanks you

[VUXE]

Outstanding professional video. Very informative. Thank you for this great share

[gpxk]

congratulations to making a fine film i found it very informative Thank you 8-)

[VKKRR]

I only found this this morning Andrew! There are alot of 'amateur' explanations about Tropo out there, but this would be the best Ive seen or read. There may be a few small things I could pick on but they are only minor of no real significance in the scheme of things and will not inhibit peoples understanding or curiosity to investigate and experiment further.
One thing you perhaps could have added inclusive with Radiation Inversion and Subsidence inversion is the phenomenon of Advection inversions, or the enhancement ahead of cold fronts, where the cold air surging in undercuts the warm air ahead of it resulting in warm air aloft and usually significant enhancement.
Overall, excellent job and I will share it now on my Twitter feed and the VHF WSPR group

[Desertwolf]

I just want to commend you on some excellent and exceptional quality videos! Best out there IMO. Please keep up the good work. They were a big help for my wife who os studying for her license. Cheers and touve gained a new subscriber!
73

[ktmman]

Please keep these videos coming... professional !!! Great work and very very informative ! Thank you ! Craig VK3NCR

[greentoptrekker]

Wonderful video and presentation. Thank you.

[se]

Most excellent! I absolutely love your videos. So well done start to finish.

[meteors]

Great propagation videos OM. Look forward to more. How about Au, AU-E, EME, Meteor scatter, etc.? Great job! Not Amateur at all, very professional.