Antenna test roof vs. attic mount

Antenna test results for 8-element coaxial collinear antenna with prostick and filter. Attic mount vs. rooftop mount (attached to pvc vent pipe)

These tests/screenshots were done within 10 minutes of each other. The results were actually surprising. I actually recieved a few more msg/sec with the attic mount. I am going to probably call this similar performance between both locations. And possibly a “tiny” bit better in the attic. ???

I do have the antenna mounted under an aluminum roof vent in the attic, possibly helping?! I dunno.

The biggest surprise was that I figured that the roof shingles, sheeting, and all the other crap in the attic would have been a bigger detriment to the number of messages recieved in the attic. It really doesn’t appear that is the case.

I was actually about to mount my antenna on the roof this week (permanently), run ground wire, coax, etc. After viewing these results, maybe i’ll just stay put in the attic.

Everyone can now attack me for having results that don’t follow the rules of science … :laughing:

Nice data.

I’d say your rooftop is better with 3.38 positions per aircraft as compared to 1.44 positions per aircraft in the attic.

Flight Aware used to have the positions per aircraft on the site pages but dropped it. Not good to compare sites since they can vary wildly but really good for monitoring performance on a single site. You’d like lots of positions per aircraft as compared to a collection of single positons for many aircraft.

It is a fast check to see if things are working correct since positons per aircraft is relatively stable.

Oh wow, I didn’t know that positions per aircraft was more important than actual message rate per second. I was only looking at the message rate per second and thought that the attic had outperformed the rooftop by a hair. Oh well, maybe I will mount to the roof after all. Thanks for the info!

I’m also very impressed with the eight element coaxial Collinear homemade antenna. It really brought my numbers through the roof. I would encourage anybody looking for an increase in antenna performance to build one themselves .

No, I think the math was wrong there. Don’t use the “aircraft total”, use the “with positions” versus “positions history”. Many of the aircraft are “Mode-S only” around here.

In that case you have (144/25) versus (284/51).

5.8 attic versus 5.6 outdoors

Sometimes even a few feet higher will bring in more interference. Maybe a DME site that comes out of the noise and garbles things.

Wow. I’m really confused now. :stuck_out_tongue_winking_eye: I will definitely have to study this some more.

Thank you

I’m currently showing 31 aircraft with 1900 positions (been running all day). 124 Aircraft total, and about 520 messages/sec

Doesn’t seem like good numbers to measure anything :slight_smile: It may be apples and oranges…

Slightly away from topic of “antenna location”, as you mentioned you are impressed by coco.

Have you compared performance of coco witk 1/4wave ground plane (Spider or Cantena), both at exactly the same location, same cable, and same receiver? Just swap coco by spider ad compare results.

Trying only one antenna without comparison with a reference or benchmark antenna (under identical conditions), and declaring it good is like running alone in a race, and declaring I am the winner. :smiley:

I have built a 1/4 wave ground plane for my airband scanner, but ended up using a yagi because I needed a more directional antenna. I’ll definitely pull out the old 1/4 wave and trim it down to 1090mhz. I’ll give it a shot.

And btw, i’m not declaring anything "the winner. " I’m just trying to get the best performance out of the coco that it possible.

My numbers for the attic mounted coco are here
If a cantenna or 1/4 wave does better, I’ll gladly switch out the coco and use it as a wiffle ball bat. :joy:

That will be a lot of trimming!
If you convert an air band antenna to adsb antenna, you will have to cut the elements to about 1/8 of their current length.

Better make a new ground plane, it is easy.

5 snips of copper, and done. 8)

No reason at all to build a new one.