Antenna ID Help

[joray]

Hello everyone,

This seems like the right place to help ID this antenna coming out of my building at work. We are a city government run greenhouse so, short of this being used for gathering weather station data, I'm at a bit of a loss for what it's doing on the building. Hopefully getting it ID'd will help solve this mystery!

 

[IAmSixNine]

Its a yagi antenna, directional. Where is it aimed at? My guess is a city tower.
UHF perhaps?
If your tied to a city buidling it could be for a wireless security system, or as you mentioned data. Go inside and see where the cable leads you.

 

[ka3aaa]

i would guess a 400 or 800 mhz yagi, aka beam antenna. the frequency depends on the size and spacing of the elements.

 

[joray]

Its a yagi antenna, directional. Where is it aimed at? My guess is a city tower.
UHF perhaps?
If your tied to a city buidling it could be for a wireless security system, or as you mentioned data. Go inside and see where the cable leads you.

I chased it through the ceiling panels and it actually ends in my office, terminating in my office. Attached is a picture of the connector.
The building is equipped with a security system that uses phone lines, so I'd be a little surprised if the antenna was for security purposes.
However, it is pointed in an easternly (maybe even southeasternly) direction, towards downtown and more city gov't buildings.

i would guess a 400 or 800 mhz yagi, aka beam antenna. the frequency depends on the size and spacing of the elements.

That's exciting you can tell that much from just a picture! Is there a chance it could be 900 mHz? I was planning on mounting a project with an outdoor antenna and it would be just too convenient if this could be a ready-made stand in.
Short of climbing up to it with a tape measure, is there a way for me to assess it from the ground? As I mentioned above, the cable does chase down into my office though I'm not sure how much help that would be.

Thank you both for taking the time to reply!

 

[chief21]

If the connector is loose (disconnected), it's obviously no longer being used for anything. Most likely was used by an earlier tenant of the building and abandoned in place.

If you can find someone that knows the history of the building, or someone that has access to an antenna analyzer (city radio shop?), they could probably tell you what frequency the antenna is designed for.

 

[mmckenna]

Hard to tell, but that looks like a mini-UHF connector. Holding a ruler or tape measure against it and taking a photo would help.

If it is a mini-UHF, it was likely connected to a Motorola radio or an older cellular setup. Pretty common with Motorola radios, used to be sort of common with some older (especially Motorola) cellular gear.

Without some measurements, it's hard to provide any useful info.

It is a Yagi design, so likely used as a base station pointed at a repeater or trunked system. If it was cellular, likely pointed at a local cell site.

Coax may or may not be any good. Often poor (or lack of) weather proofing of connectors allows water to get in and corrode the copper. If the jacket is damaged from sun exposure, it'll do the same thing. The rusty mounting mast, running rust down the wall, lack of proper coax support/strain relief would put it all in question.
If you have enough slack, the cable inside is probably good, and you could cut off the exposed stuff on the outside and re-terminate the cable.

 

[joray]

If the connector is loose (disconnected), it's obviously no longer being used for anything. Most likely was used by an earlier tenant of the building and abandoned in place.

If you can find someone that knows the history of the building, or someone that has access to an antenna analyzer (city radio shop?), they could probably tell you what frequency the antenna is designed for.

That's a good idea! I'll try and track someone down with an antenna analyzer. Unfortunately, records regarding this building or any of the documentation for the systems within are sparse and hardly reliable. City government, amirite?

Hard to tell, but that looks like a mini-UHF connector. Holding a ruler or tape measure against it and taking a photo would help.

If it is a mini-UHF, it was likely connected to a Motorola radio or an older cellular setup. Pretty common with Motorola radios, used to be sort of common with some older (especially Motorola) cellular gear.

Without some measurements, it's hard to provide any useful info.

It is a Yagi design, so likely used as a base station pointed at a repeater or trunked system. If it was cellular, likely pointed at a local cell site.

Coax may or may not be any good. Often poor (or lack of) weather proofing of connectors allows water to get in and corrode the copper. If the jacket is damaged from sun exposure, it'll do the same thing. The rusty mounting mast, running rust down the wall, lack of proper coax support/strain relief would put it all in question.
If you have enough slack, the cable inside is probably good, and you could cut off the exposed stuff on the outside and re-terminate the cable.

Getting up to antenna itself would be a tall order at the moment, but I had some calipers handy and can at least give you an idea of the connector's dimensions: the interior is 8mm wide and the center prong is 1.5mm wide. Does that mean anything to you?
I feel pretty good about the condition of the wiring, however. The weatherproofing looks thorough and intact coming into the building and the connector terminating in my office looks in great condition considering that it should be a couple of decades old. Having spent an uncomfortably long amount of time above the acoustic tiles in the ceiling, I can say with some certainty that the cable has plenty of slack.

 

[mmckenna]

Getting up to antenna itself would be a tall order at the moment, but I had some calipers handy and can at least give you an idea of the connector's dimensions: the interior is 8mm wide and the center prong is 1.5mm wide. Does that mean anything to you?

mini-UHF connector.

I feel pretty good about the condition of the wiring, however. The weatherproofing looks thorough and intact coming into the building and the connector terminating in my office looks in great condition considering that it should be a couple of decades old. Having spent an uncomfortably long amount of time above the acoustic tiles in the ceiling, I can say with some certainty that the cable has plenty of slack.

Sounds good.
What are your plans for this?

 

[joray]

Should I be so lucky and antenna ends up being suitable, I've got something of a hobby project I'd like to implement at work: I've got a LoRa gateway (915mHz) and want to get good coverage before putting some sensors out in the field. Right now I only have a little rubber ducky antenna and it's mounted to a low window.