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Maximum GMRS Antenna Height


mbrun
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About 10-years ago when I obtained my original GMRS license the FCC had a limit on GMRS antenna height. It was 20 foot above the tree or building to which it was mounted (roughly speaking). In the current regulations that 20 foot limit seems to have been complete removed. Instead, 95.1741 (regarding height) merely redirects to 95.317 that seems to indicate antennae structure over 200 foot may need to be registered with FAA.

 

So, I am curious, has the 20 foot limit truly been removed? Is it now 200 feet? If restriction is specified somewhere else if the CFR, where would I find it?

 

Michael

 

 

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§ 95.51 Antenna height.
(a) Certain antenna structures used in a GMRS system and that are more than 60.96 m (200 ft) in height, or are located near or at a public-use airport must be notified to the FAA and registered with the Commission as required by part 17 of this chapter.
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§ 95.51 Antenna height.(a) Certain antenna structures used in a GMRS system and that are more than 60.96 m (200 ft) in height, or are located near or at a public-use airport must be notified to the FAA and registered with the Commission as required by part 17 of this chapter.

 

 

Antenna height.

Rodro123, I believe 95.51 was removed as part of the 2017 FCC update. My current understanding is that 95.1741 took its place.

 

 

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.,,95.51 was removed as part of the 2017 FCC update. My current understanding is that 95.1741 took its place. ...

That is correct. However note that part 95.51 then refers to 47 CFR § 95.317 which provides restrictions for all personal radio services under part 95. However, the restrictions are pretty much the same as they were under section 95.51. But with the addition of additional restrictions if you’re near a military installation or airport.
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IIRC the FAA regs state the structure has to have a light at its highest point. It's difficult to get an antenna to work properly when it has a light and power cable on it. The issue was uncovered when antennas started being put on bridges more than towers,

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My ultimate reason for asking the question has to do with my surroundings. My home is surrounded by acres of trees on three sides. I am considering an antenna on the home and originally figured 20’ above the home. But then I thought, I wonder if I could attach to house but put up high enough to peek out above the trees.

 

Not sure if I will do that or not, but its sounds like that is legal if I decided to go that way.

 

 

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  • 3 weeks later...

I was once offered space on a very large tower array (2 towers with a bridge at the top) in Crete, Illinois. They had a UHF antenna and 1 1/2" hard line at 350'...

 

I was all excited until I was informed that they charge $1/ft' per month. No way I could afford $350/month :blink:

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A bit too much for the hobby of an individual I would say.

 

I was once offered space on a very large tower array (2 towers with a bridge at the top) in Crete, Illinois. They had a UHF antenna and 1 1/2" hard line at 350'...

 

I was all excited until I was informed that they charge $1/ft' per month. No way I could afford $350/month :blink:

 

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  • 1 month later...

Testing done? How did it go? What radio are you using?

Yes and no. I have commented on some of my activities in other posts.

 

At present, the highest I have been able to test has been 41’ to top of antenna. Still strategizing how I can the get the antenna to 60’ to button of antenna in a temporary manner at limited expense so more coverage tests can be performed. What I am wanting to determine is, if I clear the trees only marginally, will that get me the local simplex coverage I seek (solid coverage >= 3 miles base to HT and >= 9 miles base to mobile). If my simplex coverage does not increase notably at 60’, then I won’t go for the expense for permanent installation.

 

I have been pondering the purchase of DX engineering 46’ telescoping mast, but that still does allow me to clear the trees.

 

So yes, I am done testing for now. No, I have not completed testing at my desired height...yet.

 

73s

 

Michael

WRHS954

KE8PLM

 

 

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  • 3 months later...

I finally made the purchase of the HD 46’ push-up fiberglass mast I referenced in my earlier post. This weekend I rigged things up in a temporary way to conduct tests with local (and not so local) repeaters, as well as do some local simplex work.

 

The image below shows my antenna at full elevation (56’ AGL to tip of Antenna). Mast was installed in a temporary way just for testing. Eventually it will get moved next to the house. Amazing how plumb the mast was being guyed only at 7’3” (not good long term, but good enough for testing).

 

457f71231e1eef8f893206ae40cb946a.jpg

The antenna is a Comet 712EFC Collinear 9dBi.

https://www.dxengineering.com/parts/cma-ca-712ef

Cable is TMW LMR400

Mast is from DX Engineering.

https://www.dxengineering.com/parts/dxe-tfk46-hd

 

All of my testing consisted of using two handheld 5w radios. One feeding the Comet antenna, one in the car using an MXTA-26 antenna.

 

First, the high-point of the testing. I was able to communicate from my home southeast of Cincinnati to the Dayton 700 repeater located 50 miles north(straight line distance) using approx 3 watts of input power into the antenna. Signal report from a Dayton area resident was “very good” and “into the repeater solid”, perfectly suitable for a QSO. That alone made my weekend.

 

On the local front I was able to get into three local repeaters located 20, 21 and 26 miles way. Got in with full quieting to the one 20 miles away (“just as though I was next door”), and with just a hint of noise on the ones 21 and 26 miles away. Getting the antenna up high obviously makes a huge difference.

 

On the simplex front I found I could achieve pretty reliable coverage out 4 to 5 miles where things transitioned to hit and mis out to about 7-8 miles when all seemed to die completely. I expect the reliable range will decrease as foliage comes back. Not bad though for a couple of lower power HT and with good external antennas.

 

It will be nice to experience the positive change to simplex coverage after I up the power of the base and mobile to legal limits.

 

 

Michael

WRHS965

KE8PLM

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This needs simplified.

 

Repeater antenna.  No Limit to height in rules.  In certain area's around airports FAA regulations limit the tower height.  In all locations, towers exceeding 200 feet need to be registered with the FAA and lit with a type accepted lighting system.

Base station antenna's.  Meaning antenna at a fixed location that is talking and receiving from mobile and other bate stations where no repeater is involved.  50 feet

Control Stations.  Meaning a fixed station (base type station) that is communicating with an off site repeater to extend coverage.  I believe is 20 feet (for sure with commercial radios but this run gets broken constantly)

No limit on mobile / portable antennas that I have seen in rules.

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Thanks Michael for sharing this... You're are a good teacher.  

Jack

I finally made the purchase of the HD 46’ push-up fiberglass mast I referenced in my earlier post. This weekend I rigged things up in a temporary way to conduct tests with local (and not so local) repeaters, as well as do some local simplex work.
......................

Michael
WRHS965
KE8PLM

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Control Stations.  Meaning a fixed station (base type station) that is communicating with an off site repeater to extend coverage.  I believe is 20 feet (for sure with commercial radios but this run gets broken constantly)

 

Actually, the limit is 20' higher than the support structure. If one lived in the penthouse of a 40 story building, imagine the range one could enjoy even on simplex!

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I finally made the purchase of the HD 46’ push-up fiberglass mast I referenced in my earlier post. This weekend I rigged things up in a temporary way to conduct tests with local (and not so local) repeaters, as well as do some local simplex work.

 

<snipped for brevity>

The antenna is a Comet 712EFC Collinear 9dBi.

https://www.dxengineering.com/parts/cma-ca-712ef

Cable is TMW LMR400

Mast is from DX Engineering.

https://www.dxengineering.com/parts/dxe-tfk46-hd

 

That is a very nice antenna. I installed one on the roof of my house about seven years ago on a 20' mast secured by a heavy duty tripod. I went a bit overboard by using 7/8" Andrews heliax. It's been a rock-solid performer and has survived many gusts in excess of 60mph, and a derecho last year with highest steady winds of ~90mph!  See: https://twitter.com/i/status/1292938287296974856 showing an apartment building being "de-roofed."

 

Those masts are great, although measuring and marking each section and gluing the toggle clamps was a PITA! I have two of them and use the tall tripods from MFJ along with two levels of guy lines to support my G5RV (106' HF antenna) on field days and other club events such as POTA (Parks on the Air) activations.

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You know, I was watching that video expecting to see an antenna still standing while the roof was ripped off.

 

I read about the glue up PITA issue you talked about and was fretting it too. The version I received did not require glue. The couplers simply slide over the lower section and are tightened in place with an allen wrench. Nice!

 

That is a very nice antenna. I installed one on the roof of my house about seven years ago on a 20' mast secured by a heavy duty tripod. I went a bit overboard by using 7/8" Andrews heliax. It's been a rock-solid performer and has survived many gusts in excess of 60mph, and a derecho last year with highest steady winds of ~90mph! See: https://twitter.com/i/status/1292938287296974856 showing an apartment building being "de-roofed."

Those masts are great, although measuring and marking each section and gluing the toggle clamps was a PITA! I have two of them and use the tall tripods from MFJ along with two levels of guy lines to support my G5RV (106' HF antenna) on field days and other club events such as POTA (Parks on the Air) activations.

 

Michael

WRHS965

KE8PLM

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Actually, the limit is 20' higher than the support structure. If one lived in the penthouse of a 40 story building, imagine the range one could enjoy even on simplex!

 

 

That's the only thing that makes me envious of the 15 story building at the top of my line of sight facing north.  If we had a repeater up there, it would be golden

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