Multi use antenna questions.

[WRCY896]

I have a repeater at my house which I acquired by accident two years ago when I got my license. It works well with an HT here at the house, and I do not have a base. I run it with a slim Jim Gmrs tuned antenna.

 

I have been trying to get the repeater on a mountain top with no success, so I have accepted the fact the repeater will likely be permanent at my property. There is a lot of good view feom where I am, so that is a positive.

 

Last year I acquired a 20 foot section of comm tower which is 2 feet wide on each side.

 

I also have plans in the future to get my HAM and have a VHF and UHF repeater in view. Not sure what else HAM might bring me later.

 

I plan to bury the bottom 4 feetand put the tower next to my shed which will be my radio shack and gun/reloading room.

 

No HOA or county code issues, but I am in an FAA zone and am limited to 20 feet with no permit.

 

What problems will I run into with spacing and elevation of various antennas on the same tower?

 

First, let's presume GMRS, VHF, UHF.

 

Any other suggestions are welcome as well.

I attached pictures of the tower and my current antenna.

 

Pictures had to be resized, so they may appear weird.

[kidphc]

Certain frequency can interact.

 

Spacing/distance can be partially resolved by having one vertical pointing upwards and the other facing downwards on a cross tee. With a 20' tower that can be an issue. Since some of the nicer vertical antennas can be in excess of 20' by themselves. Would be kinda funny if you were constantly kicking the tip of your upside down antenna. Well not really.

 

Grounding should be done at before the tower's foundation is poured

 

As far as the faa permit, I didn't think it was massively difficult. The installation of a beacon light is a requirement after a certain height, which sounds like you are at.

 

Which ham ticket where you shooting for?

 

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[WRCY896]

Tech for sure first, and will try for my general at the same time. I will get the books here soon to start studying.

 

For starters, it would just be VHF and UHF.

 

I did a quick search and it doesn't look like the application is a big deal for the FAA, so I will probably get that going anyway. It could still gain me a few feet even without the HAM ticket.

[kidphc]

Tech for sure first, and will try for my general at the same time. I will get the books here soon to start studying.

 

For starters, it would just be VHF and UHF.

 

I did a quick search and it doesn't look like the application is a big deal for the FAA, so I will probably get that going anyway. It could still gain me a few feet even without the HAM ticket.

Definetly do the tech and general at the same time. I wish I had alot of the material is the same.

 

Be on the look out for silent key estates. Their families alot of times will just want their old towers removed, which they will tell you to take apart. Then you may get a taller tower using some of your and buddies time. As well as get some free antennas. Give you a chance to inspect their install as well.

 

If you get lucky your 20' section may attach to the one you just pulled down and you get more height.

 

Downside setting up the tower cost $$$. Just in quality cabling it adds up.

 

Either case, good luck. Have a feeling you'll be that "guy" in the area.

 

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[mbrun]

I would not let the permit scare you away. Just because you need a permit does not mean you are not eligible for increased height. They probably just want make sure your elevation stays within the safe range for you distance you are from the air field.

 

In the event that you remain limited in height you can purchase multi-band antennas so that a single stick could perhaps serve you well. Recently learned that Diamond has a custom service available. A local GMRSr and ham reported this to me just two weeks ago as a result of a purchase he made for a dual-service repeater system he is installing.

 

If you cannot mount the antennas on the same tower and with vertical separation between them, then horizontal separation is likely what you will need. The more separation you can achieve the less transmissions from one of your radios will de-sense the radios served by on the other. You could perhaps put both UHF services (70cm and GMRS) on the same custom antenna but you would need to use external band pass filters and diplexers to split the band between the different radios. I would expect that if done well you would lessen your potential for UHF de-sense issue.

 

You are in a good position to do some experimentation on your property to get a good sense for how things would perform before you commit to any high-dollar equipment. You may also be able to reach out to a local ham club. They may have members that might enjoy some field-day-like experiments at your home.

 

I have a repeater at my house which I acquired by accident two years ago when I got my license. It works well with an HT here at the house, and I do not have a base. I run it with a slim Jim Gmrs tuned antenna.

 

I have been trying to get the repeater on a mountain top with no success, so I have accepted the fact the repeater will likely be permanent at my property. There is a lot of good view feom where I am, so that is a positive.

 

Last year I acquired a 20 foot section of comm tower which is 2 feet wide on each side.

 

I also have plans in the future to get my HAM and have a VHF and UHF repeater in view. Not sure what else HAM might bring me later.

 

I plan to bury the bottom 4 feetand put the tower next to my shed which will be my radio shack and gun/reloading room.

 

No HOA or county code issues, but I am in an FAA zone and am limited to 20 feet with no permit.

 

What problems will I run into with spacing and elevation of various antennas on the same tower?

 

First, let's presume GMRS, VHF, UHF.

 

Any other suggestions are welcome as well.

I attached pictures of the tower and my current antenna.

 

Pictures had to be resized, so they may appear weird.

 

Michael

WRHS965

KE8PLM

[WRCY896]

I just applied for the permit. 40 feet.

 

Pretty easy and I don't see any issues regarding approval. I qm not in the approach, just within the radius.

[mbrun]

I just applied for the permit. 40 feet.

 

Pretty easy and I don't see any issues regarding approval. I qm not in the approach, just within the radius.

Great. I think then could probably work out a scenario where your GMRS repeater antenna up top and then side-mount a dual-band amateur antenna lower on the tower.

 

 

Michael

WRHS965

KE8PLM

[kidphc]

Great. I think then could probably work out a scenario where your GMRS repeater antenna up top and then side-mount a dual-band amateur antenna lower on the tower.
 
 
Michael
WRHS965
KE8PLM

Don't you get more isolation by mounting it below and to the otherside?

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[mbrun]

Don't you get more isolation by mounting it below and to the otherside?

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Not sure I understand the question. Otherside? Perhaps you can clarify.

In the scenario I presented, I was imaging one vertical antenna on top of the mast, at say 40’. Then, lower on mast, perhaps at 20’ feet, another vertical antenna. The lower antenna could not be mounted collinear with the top antenna as it would need to be offset from the mast and coax that serves the upper antenna to work correctly. But being below the upper antenna as it would be, there would be some isolation that would occur. Not perfect, but closer to the null of the donut formed by the upper antenna and vice versa. This arrangement would be far better than two antennas mounted adjacent and parallel.

Comments?


Michael
WRHS965
KE8PLM

[kidphc]

Think I misunderstood your original post. I had always thought that mounting one upside down also accomplished the something.

Reading your second post I think we are on the same page.

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