VHF/UHF HT Maximum Achievable Range - Part 2: Understanding Line of Sight & Horizon
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- Опубліковано 28 жов 2024
- In Part 2 of this series, I discuss the importance of understanding VHF/UHF line of sight signal issues, natural horizon and horizon extension tactics.
Here's that formula I mentioned:
Antenna height 0.00 (meters) x 3.569 (kilometers) = 0.00 (kilometers) to horizon.
In the UK we have PMR446 CB radio power output 0.5w and I always wondered why not 5w since passing my foundation course I can understand now that extra watts wouldn't achieve much on 70cm, great videos
Outstanding instruction. Broken down so most all can understand. I have a medium background in understanding comms from my time in the Army in the 80's & 90's. At the platoon level we worked with the PRC 77 and then later came the handheld PRC 127 which was programmable like the UV5R. Can't wait for the segment on directional antennas & signals. Back then we used a Long Wire Antenna that was on a fly fishing reel, Keep up the great work.
Great info Scott. If you are a new Ham or GMRS operator, be sure to watch the next video. It's amazing how much difference having the right antenna can make in distance. I'll take a better antenna with a 4 watt radio over a crappy stock antenna with a 10 watt radio any day.
Scott very good video thank you for sharing 👍
I really like your videos, as a new ham I really dove deep trying to achieve maximum range for vhf from day one after my call sign hit the books. Here in Alaska it is very mountainous and hilly terrain so this can come as quite a challenge for simplex operation. Several days worth in hours of testing I found that a lot of information found in the ARRL handbooks about LoS comms is not entirely correct in all situations. I wanted to start small and make small adjustments to find out what really works and changes things (sometimes small adjustments do a lot). I started with two handhelds, one in my house with an old cell phone recording the receiving frequency, the other in my truck with me creating distance on the move. I found that I could only go about .5 of a mile in all directions from my house on 5 watts until I lost comms. After that I constructed and simple dipole and hung it on the roof line of my house. I repeated the test with some decent results, maximum range of about 1.2 miles in some directions and the same as the last test in others. I still wanted more out of it so I purchased a cheap comet mag based antenna for my truck to hook my other handheld to and got very good results! In only one direction I could get 5.5 miles out of it! But in other directions I could only get about 1 mile, even at 18 miles where I have perfect line of sight communication to my house from elevation on a mountain I could not make contact. I pulled the plug and bought a used 50 watt vhf radio off eBay and now that perfect line of sight communication is clear as day, I can make some what reliable communication from about anywhere without line of sight for about 6-10 miles. In some cases radio output power can over come line of sight communications unlike what the ARRL handbook says
Scott, great video and very well presented.
Another outstanding video Scott.
Thanks for mentioning the range 3 mile absolutely understand
This is fantastic. Super clear and useful. Are you planning on doing more videos on this series?
Great points on this.
Well you're absolutely right Scott then the two days were around yeah I know pretty much how to do your own repairs but now with everything transistor I'm same way as you I'm just the pilot to the plane I'm not the mechanic 👍
I've used VE2DBE's software extensively. You need to be conservative if you want FQ. But I've found the geo-plotting quite accurate.
120 miles is outstanding. I've never gone beyond 90 mi. - HT to repeater. But have done 45 miles HT to HT with DFQ.
Aside from obstructions, which cast a propagation "shadow," there is the Inverse Squire Law. That is, at ever increasing distances, the signal fades at some point below the receiver's signal to noise threshold and becomes unintelligible. As an example, if you were to install a 5 watt lightbulb in your porch light socket, it would illuminate the immediate surroundings. You'd probably see it if standing back at 100m or so. But at 10 miles, it may appear dimmer than a dim star in the sky - lost to the background noise, so to speak. Same with RF radio signals. In messing with this, theoretically, I suspect about 200 miles might be a good estimate for VHF / UHF from an HT, at 2.5 watts, nominal antenna. You can push out a signal with more power or a gain antenna, but you'll still be working against two things you'll not solve: The curvature of the Earth I think mentioned in the video, and the Inverse Square Law. You can win at this game but only so far. ~WA4JC
I believe that since both of your hypothetical stations are transmitting at 6 feet above the plane of the earth, the radio horizon for each is 3 miles, and the total is 6 miles; but like you said, getting one or both up even a few more feet helps. I have stood in the bed of my truck to improve effective range jsut enough to pass traffic.
Great video! Thank you!
Good info
My record was about 17 miles with a FRS. When I was with the Campo Minunite men. Campo is rolling desert terrain.s
And to challange your theory, there is the magic of tropospheric, When weather conditions are just right, a 2 meter signal can travel great distanced. Check out Gordon West's podcast on it.
You are not challenging any Line of Sight theory .
Will you be discussing the use of a "tiger tail" attached to the HT?
I use a 19 inch long Signal Stick antenna on my Ht's. I have four HT's, and four Signal Sticks. They are 19 inch long quarter wave antenna's. But yes I tell people, three to five miles. I've been licensed as a Ham, since 2016. And I kind of specialize in HT's.
We do Car convoy a lot .
With GMRS antenna centered on top of car roof .
Range is max out at around 3 miles too . 5 watts minimum power or 50 watts max power .
Still same 3 miles 😄.
I have power lines at the front of my house, will this affect where I should locate my external antenna?
metric formula?!? cool. 73
saw KENWOOD TS-480HX in the background, what can you tell about it?
It's a 200w HF mobile rig that I'm incorporating into a Go-Box. It's a discontinued model but it's still a very capable rig. I won it at one of our radio club Christmas party raffles.
Part two and still peed off
"win an argument with a flat earther" LOL
Lol, love the flat earther comment haha