Thoughts on what this antenna structure is?

[berkeman]

I saw this antenna matrix on the north coast of California this week on vacation (a couple miles north of Half Moon Bay). It's located about 1/4 mile from the beach on Highway 1. There is a powerline running past it, but it looks to just be getting much of its power from a trickle charge from a meter square solar panel.

Do you have any ideas what it might be used for? I'm guessing that there are 7 horizontal dipoles in the disks, aimed in different directions, but for what? A multi-directional low power repeater?

I couldn't easily get closer to the antenna pole (traffic is crazy on Highway 1 there). Maybe that would have provided more clues.

 

[Averagesupernova]

Multi directional that is horizontally polarized could be an ATV repeater. It seems a bit low for that. But you never know.

 

[jim hardy]

my guess

http://www.aqmd.gov/home/library/air-quality-data-studies/air-quality-monitoring-studies/near-road-air-network][/PLAIN]
Introduction
On February 9, 2010, U.S. EPA promulgated new minimum monitoring requirements for the NO2 monitoring network in support of newly revised 1-hour NO2 National Ambient Air Quality Standard (NAAQS) and the retained annual NAAQS. To implement the new monitoring requirements, SCAQMD is installing near-road NO2 monitoring stations at locations where peak hourly NO2 concentrations are expected to occur within the near-road environment in larger urban areas with consideration to traffic volumes, fleet mix, roadway design, traffic congestion patterns, local terrain or topography, and meteorology in determining where a required near-road NO2 monitor should be placed. Information on how sites are selected was presented at the http://www.aqmd.gov/home/library/clean-air-plans/monitoring-network-plan/near-roadway-air-quality-monitoring-workshop and also the Annual Network Plan Workshop (PDF, 5.3MB).

http://hank.baaqmd.gov/tec/maps/dam_sites.htm

right neck of the woods ?

 

[anorlunda]

How close is it to that power line?

What are those things three feet above the ground?

There appears to be something on the telephone pole at the same height as the big cylindrical thing on the antenna.

 

[dlgoff]

my guess

It does look similar to this Air monitoring device installed at San Ysidro border crossing.

 

[meBigGuy]

I think it is a stand-alone monitoring station of some sort. Those stacked disks appear often in monitoring equipment, and solar power makes sense for those applications.
Were you near the diablo canyon power plant? Was it in a wetlands? Can you post a higher resolution image?

 

[berkeman]

Wow, thanks for the insights, folks! It does indeed look to be an air quality monitoring device of some sort. Learn something new every day around here...

 

[cpscdave]

I totally could be wrong here.
But I don't think this is an antenna or some sort of monitoring equipment. Rather it is a tsunami warning siren.
I saw a few of those in around Tofino on Vancouver island, given the location and placement of whatever they are the only thing that made sense was a warning siren.
If you google images Tsunami warning siren you see various designs including a bunch that look similar to what you've posted.

 

[berkeman]

I totally could be wrong here.
But I don't think this is an antenna or some sort of monitoring equipment. Rather it is a tsunami warning siren.
I saw a few of those in around Tofino on Vancouver island, given the location and placement of whatever they are the only thing that made sense was a warning siren.
If you google images Tsunami warning siren you see various designs including a bunch that look similar to what you've posted.

You might be right! It certainly makes a lot more sense, since the Half Moon Bay area is one of the most vulnerable areas in the state of California for tsunami inundation.

I found this document about the tsunami preparedness for the San Mateo County coastline, and the picture of the siren has a different actual set of horns on it, but the same kind of solar panel:

https://www.google.com/url?sa=t&rct...al.pdf&usg=AFQjCNFYP-ek7RJlknduEAfSahHxH1hDDA

Other Google Images searches shows a mix of the traditional horns and the weird vertical array that I took a picture of. Guess I'm just going to have to get a closer look the next time I'm over at the coast. Thanks all