Antenna mast question

[scan_nepal]

The goal is to erect a pole about 30 ft tall in the roof. House construction in this part of the
world is pillar based, that looks similar to the photo below:

Anyways, I am thinking of inserting the 5 ft tall / 2 inch diameter pipe inside the pillar during
pouring concrete phase. Once it dries up, I want to tie antenna pole made of PVC or maybe
even bamboo to hook future antenna that is not too heavy. E.g. ground plane, 3 element
yagi etc.

Any inputs for such system would be greatly appreciated. No need to worry about tornado
or damaging winds in my city. The maximum wind speed is about 9 miles/hour or
4 meters/second. Below is my rough plan I drew. Thanks again all.

 

[WB9YBM]

The goal is to erect a pole about 30 ft tall in the roof. House construction in this part of the
world is pillar based, that looks similar to the photo below:
View attachment 92030
Anyways, I am thinking of inserting the 5 ft tall / 2 inch diameter pipe inside the pillar during
pouring concrete phase. Once it dries up, I want to tie antenna pole made of PVC or maybe
even bamboo to hook future antenna that is not too heavy. E.g. ground plane, 3 element
yagi etc.

Any inputs for such system would be greatly appreciated. No need to worry about tornado
or damaging winds in my city. The maximum wind speed is about 9 miles/hour or
4 meters/second. Below is my rough plan I drew. Thanks again all.
View attachment 92029

Eventually the mast's going to need replacing: when it gets too rusty, bent from a burst of strong wind (no one's immune), so I'd recommend some kind of elongated hole in the pillar into which a mast can be inserted. This way the mast can get replaced or upgraded if/when needed.

 

[scan_nepal]

Eventually the mast's going to need replacing: when it gets too rusty, bent from a burst of strong wind (no one's immune), so I'd recommend some kind of elongated hole in the pillar into which a mast can be inserted. This way the mast can get replaced or upgraded if/when needed.

Thanks for your input. Yes, you are correct about the possibility of replacement of the mast down the road. If some type of elongated hole in the pillar is used, the problem could be possible water seepage/gathering in that hole. One possibility is to use this type of plate:

If the plate gets corroded, I can simply weld another plate. This will involve dismantling the antenna and some major work. But I suppose, this
is how it is professionally done.

 

[buddrousa]

Just note those bolts on the tower legs are not factory and will rust bad as they are not galvanized.

 

[prcguy]

I believe the bolts for a Rohn 25 and similar are supposed to be grade 5 and the ones in the pic look like Home Depot junk. Are some of those carriage bolts???

QUOTE="buddrousa, post: 3383026, member: 9642"]
Just note those bolts on the tower legs are not factory and will rust bad as they are not galvanized.
[/QUOTE]

 

[mmckenna]

Thanks for your input. Yes, you are correct about the possibility of replacement of the mast down the road. If some type of elongated hole in the pillar is used, the problem could be possible water seepage/gathering in that hole. One possibility is to use this type of plate:

As others have pointed out, whoever made that photo/video used the wrong bolts.
It's usually a good idea to take anything from amateur radio operators with a fair amount of caution until you've double checked with the manufacturer. Those are not the correct bolt for holding that hot mess together.

A properly galvanized pipe should work just fine. If you just need a pole to mount an antenna on to, there's really no point in installing an entire tower. Galvanized posts get used for fence posts and street signs and don't have a problem stuck in concrete. What you don't want to use is electrical conduit.
Make sure you cap off the top end to keep any moisture from getting inside.

 

[MUTNAV]

The goal is to erect a pole about 30 ft tall in the roof. House construction in this part of the
world is pillar based, that looks similar to the photo below:
View attachment 92030
Anyways, I am thinking of inserting the 5 ft tall / 2 inch diameter pipe inside the pillar during
pouring concrete phase. Once it dries up, I want to tie antenna pole made of PVC or maybe
even bamboo to hook future antenna that is not too heavy. E.g. ground plane, 3 element
yagi etc.

Any inputs for such system would be greatly appreciated. No need to worry about tornado
or damaging winds in my city. The maximum wind speed is about 9 miles/hour or
4 meters/second. Below is my rough plan I drew. Thanks again all.
View attachment 92029

Just a quick point... The location looks like a possible preferred strike point for lightning. Lightning seems attracted to corners of buildings, I don't have the references, but I would research and implement the most stringent lightning protection scheme possible.

Thanks
Joel

 

[scan_nepal]

I believe the bolts for a Rohn 25 and similar are supposed to be grade 5 and the ones in the pic look like Home Depot junk. Are some of those carriage bolts???

You probably meant something like this (found off amazon):

 

[scan_nepal]

As others have pointed out, whoever made that photo/video used the wrong bolts.
It's usually a good idea to take anything from amateur radio operators with a fair amount of caution until you've double checked with the manufacturer. Those are not the correct bolt for holding that hot mess together.

A properly galvanized pipe should work just fine. If you just need a pole to mount an antenna on to, there's really no point in installing an entire tower. Galvanized posts get used for fence posts and street signs and don't have a problem stuck in concrete. What you don't want to use is electrical conduit.
Make sure you cap off the top end to keep any moisture from getting inside.

Yes, I do intend to cap off the top end and maybe check every few years to make sure it is holding fine from the elements. Galvanized water pipes are available in the market and I am guessing those should stay put for a long time.

 

[scan_nepal]

Just a quick point... The location looks like a possible preferred strike point for lightning. Lightning seems attracted to corners of buildings, I don't have the references, but I would research and implement the most stringent lightning protection scheme possible.

Thanks
Joel

The stock picture in the original post was just for reference. The actual location of the planned mast will be in the center of the building as shown below:

 

[WB9YBM]

Thanks for your input. Yes, you are correct about the possibility of replacement of the mast down the road. If some type of elongated hole in the pillar is used, the problem could be possible water seepage/gathering in that hole.

That's why, at the bottom of the hole, a typical installation will include gravel and sand under the cement, to give drainage. (I picked up that trick when putting an over-sized pipe in the ground that held up a collapsible cloths-drying stand in the back yard...)

 

[mmckenna]

The stock picture in the original post was just for reference. The actual location of the planned mast will be in the center of the building as shown below:
View attachment 92096

If that's your application, then you may want to rethink this.

If you are doing a tower, they make brackets especially for this. Go with the manufacturers specified design. I have a couple of towers on top of reinforced concrete buildings, and one uses a shelf type base, and the other one is mounted on top of two I-beams that bridge across the roof.

If you are going to do a pole, then use brackets to support the pole, don't mount the pole in the concrete. You could have a welder fabricate two brackets that could be bolted into the finished concrete.

 

[MUTNAV]

Go with the manufacturers specified design.

That sounds like a great idea. The manufacturers probably had engineers actually do the design work in advance. When messing with roofs and towers, errors can get expensive.

Thanks
Joel

 

[mmckenna]

That sounds like a great idea. The manufacturers probably had engineers actually do the design work in advance. When messing with roofs and towers, errors can get expensive.

Thanks
Joel

Yeah, so I think a lot of us thought this was going on a single family residence.
From the picture, it looks like a apartment/condominium. Not sure what the building/electric codes are like in Nepal, but I'd think there would be some differences between a hobby type install on a home versus a commercial type install on a multiple family building.

Grounding will be important. Simply sticking a pole into concrete isn't going to work. The grounding will (probably) need to involve building steel, any metal plumbing, building electrical ground, and maybe additional ground rods.

Support for the tower needs to be designed with the person who is designing the building. A couple of expansion bolts into masonry probably isn't appropriate for anchoring a tower like that. Through bolting might be a better option, and if there is a steel frame under the masonry, working with that.

Having a tower come down on someone due to improper installation won't do any good. Consider the weight of the tower, cable, antenna, and climbers as part of the design. Wind load, ice load (if you get ice in the area) need to be figured in also. Usually manufacturers of the towers will have some documents that can help you with the design, but the anchoring/mounting really is a local thing.

I wish I was at work today, I've got a couple of similar installs that I could take photos of for you.

 

[scan_nepal]

Yeah, so I think a lot of us thought this was going on a single family residence.
From the picture, it looks like a apartment/condominium. Not sure what the building/electric codes are like in Nepal, but I'd think there would be some differences between a hobby type install on a home versus a commercial type install on a multiple family building.
*snip*

Actually it is not a apartment or condominium. Just a single family design. And, I am not planning to erect any fancy tower system. The maximum height will be no more than 30 ft pole attached side by side to the planned mast stuck in concrete pillar. And I will put the guy wire to the long pole so it won't swivel too much.

 

[buddrousa]

A unsupported 30 foot pipe will move alot in the wind also what are you putting on top for an antenna?

 

[WB9YBM]

If that's your application, then you may want to rethink this.

If you are doing a tower, they make brackets especially for this. Go with the manufacturers specified design. I have a couple of towers on top of reinforced concrete buildings, and one uses a shelf type base, and the other one is mounted on top of two I-beams that bridge across the roof.

If you are going to do a pole, then use brackets to support the pole, don't mount the pole in the concrete. You could have a welder fabricate two brackets that could be bolted into the finished concrete.

Or maybe even go a step further; it sounds like we're talking about some kind of commercial building in which case it would probably be a good idea to get the building maintenance department (or someone similar) involved. Since these folks know more about the construction of the building, they'd be more likely than the rest of us to know how to mount something securely and safely. (that would also avoid potential lawsuits if something goes wrong.)