UHF Propagation

[tweiss3]

I figured I'd share this here for anyone wondering. If you have been around radio for any time at all, I'm sure you have heard of "E" skip or tropospheric propagation that happens in the summer time with 2 meters (144 mHz) and below.  The question has always been, well, does it ever happen to UHF. The answer is yes, but a little differently, which I didn't quite understand until yesterday.

Now, this was on the 70cm ham band, but could apply equally to GMRS being not that far off in frequency. Yesterday I woke up and had a good drive to a meeting. It was extremely foggy (important) and the 2m repeater I usually listen to was down. I started scanning with my radio, and ended up picking up a pretty good conversation, so I listened for quite a while. Never jumped in, but after my meeting, I figured I'd throw my call out. Luckily I got a response. Had a great 20 minute qso, and figured I was coming through a repeater in the middle of the state (wow). When I had more time, I looked up the repeater, my location and ran a line of site. Now I was in my truck (6' AGL 50W) and the repeater was on a tower (230' AGL 80W). Attached is the line of site calculation. No way in heck to make that 97 miles on a normal day on UHF.

So how did that happen? I started reading a bit more, and similar to right before a large storm mass when 2m/6m & 10m propagation picks up, a massive temperature inversion (remember the fog) can provide great bending/bouncing capabilities for UHF. I'm sure I read about it before studying for my ham licenses, but never had the pleasure of expeiencing.

How did I confirm it was the repeater I thought it was? I was using Yaesu System Fusion, and it gave me the repeater ID, and checked based on the frequency. The repeater owner, with whom my qso was with, also confirmed on the controller it was an RF connection.

Keep an ear out, you may experience something just as crazy. I've had voice contacts overseas with only 5 watts on HF, but UHF at that distance just boggles my mind.

[kidphc]

Tropho ducting rocks.

I want to experience sporadic e, I can't tell the difference unfortunately.

Sent from my SM-G975U using Tapatalk

[mbrun]

I figured I'd share this here for anyone wondering. If you have been around radio for any time at all, I'm sure you have heard of "E" skip or tropospheric propagation that happens in the summer time with 2 meters (144 mHz) and below.  The question has always been, well, does it ever happen to UHF. The answer is yes, but a little differently, which I didn't quite understand until yesterday.
Now, this was on the 70cm ham band, but could apply equally to GMRS being not that far off in frequency. Yesterday I woke up and had a good drive to a meeting. It was extremely foggy (important) and the 2m repeater I usually listen to was down. I started scanning with my radio, and ended up picking up a pretty good conversation, so I listened for quite a while. Never jumped in, but after my meeting, I figured I'd throw my call out. Luckily I got a response. Had a great 20 minute qso, and figured I was coming through a repeater in the middle of the state (wow). When I had more time, I looked up the repeater, my location and ran a line of site. Now I was in my truck (6' AGL 50W) and the repeater was on a tower (230' AGL 80W). Attached is the line of site calculation. No way in heck to make that 97 miles on a normal day on UHF.
So how did that happen? I started reading a bit more, and similar to right before a large storm mass when 2m/6m & 10m propagation picks up, a massive temperature inversion (remember the fog) can provide great bending/bouncing capabilities for UHF. I'm sure I read about it before studying for my ham licenses, but never had the pleasure of expeiencing.
How did I confirm it was the repeater I thought it was? I was using Yaesu System Fusion, and it gave me the repeater ID, and checked based on the frequency. The repeater owner, with whom my qso was with, also confirmed on the controller it was an RF connection.
Keep an ear out, you may experience something just as crazy. I've had voice contacts overseas with only 5 watts on HF, but UHF at that distance just boggles my mind.

Very cool you got to experience first hand. A similar thing happened in recent weeks on a repeater here in Cincinnati. I listened to a QSO between a local ham and another one that was operating just southwest of Louisville KY. About the same range as you. No line of sight there either. Just a limited window of the right conditions.


Michael
WRHS965
KE8PLM

[tweiss3]

41 minutes ago, mbrun said:

Very cool you got to experience first hand. A similar thing happened in recent weeks on a repeater here in Cincinnati. I listened to a QSO between a local ham and another one that was operating just southwest of Louisville KY. About the same range as you. No line of sight there either. Just a limited window of the right conditions.


Michael
WRHS965
KE8PLM

That's the crazy thing, it was extremely wide spread. It covered 20 miles east-west on I90, the same 20 miles east-west on I480, at at least 10 miles north-south on I71. It was also over 1 hour 15 minutes at a minimum of an opening.