FlightAware Discussions

Moved antenna to attic ... and no improvements

Hi All, two days ago I moved antenna from 3rd floor window (on the side of the house) one floor up into attic to middle of the house (highest point available) and got no visible improvements in number of planes or messages (actually maybe 10-15% more messages).

Was I wrong to expect improvements? I thought higher elevation and less obstacles at least in one direction will bring something. But looks like I was wrong. Why?

I had similar results when I tested in my attic (above the 2nd floor) or anywhere indoors. I tested with the FA antenna and once with the much larger DPD 1090 antenna. In my case the issue is two-fold. 1) My house has above average wood/wall/roof thickness and 2) I’m surrounded by tall forest/trees on 3.5 sides which attenuates signal and creates a scenario of kinda having the antenna indoors twice.

Happiness was not achieved until making an outdoor location work, eventually on an antenna mast 30 feet up. (Still have tree attenuation, but range, messages, plane count is about 3x better than I imagined would be possible for my location).

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There is a thread somewhere here which stated that the elevation of the antenna is not that critical if the rest of the condition did not change (as long as you do not have a large difference)

I would assume the move to one floor up did not improve anything as long as your max range (heywhatsthat.com) was already good

Number of planes will stay the same if you still cover mostly the same airways.
But for how long you see them might change.

Really you’d need a before and after of something like this (from tar1090):

Or you can use this: https://github.com/caiusseverus/adsbcompare#polarsh

Actually even your FA stats should give you a rough indication, you can select a day before and after the change and compare.
Open in two tabs, select Thursday and the Thursday before that, then switch tabs and compare polar plots.
But it’s not as detailed as the other two methods mentioned.

Yeah, did that. We some imagination :slight_smile: I can see that it now has more reach in obstructed before direction. But at the same time I think it lost some distance in other direction.

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Another simple test you can do is to open your local PiAware map in your browser, and then in another tab open the main FlightAware site. Center that map over your location and adjust to a similar zoom level.

If your local map mostly shows the same planes as the FA map, chances are you are already seeing all of the planes that there are to see. If you are obviously missing a bunch, then there is improvement to be had in your hardware and/or location

From what I see I have pretty good coverage within 50 miles. Within 100 miles relatively good. Further away only high altitude planes and spotty coverage.

Moving antenna outside is not an option in a short term. I’m thinking about updating RTL-SDR to AirSpy mini and/or move from custom 10 element collinear to ADSBx antenna.

What upgrade do you think will bring more improvements?

Do you have any amplification in the chain? If not, the cheaper route might be FA Pro stick/plus (Get the blue pro stick plus if you will benefit from the filter). If you already have an LNA, then AirSpy will probably be better. It was for my situation.

Weren’t you pretty restricted according to heywhatsthat?

And as david said, filtered LNA before you think about airspy.

If you’re really sure your colinear is good you don’t really need a commercial antenna.
Could also try building this: https://www.mictronics.de/posts/G7RGQ-Antenna-1090MHz/
I believe it’s easier to get right than colinears and should have good reception.

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Yes, I already have Uputronics LNA.

heywhatsthat shows 250 miles for my location. But it does not take into account buildings and trees around.

You’re really fighting an uphill battle then.
It’s also not like there is a lack of receivers in the New York area :slight_smile:

Anyhow the antenna i mentioned editing my last post might be a good alternative to buying an antenna.

It seems like something wrong with G7RGQ web site but Google remembers everything. I really doubt I will be able build that one with necessary accuracy and I don’t have tools to tune it.

Probably will buy ADSBx or FA antenna as I really want to compare what I built vs commercial one. But at the same time want to see what Airspy mini can do for me. I have tons of nearby planes from 3 major NYC airports and few local airports. Wondering if Airspy can help with nearby traffic and keep or increase distance.

It depends on your geo restriction.
I am located in Germany and it looks like i have already my max reception.
Using the blue FA Pro Plus stick with a Jetvision antenna. I’ve tried an additional filter - no change
I also ordered an Airsquitter (a variant of Radarcape) which did not deliver a better performance.
Finally i asked about an Airspy and @wiedehopf replied that he also see it very unlikely that there will be an improvement.

That’s why i now stick with my current setup (Raspberry 4, blue Stick, Antenna)

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With an indoor antenna you can often get at least small improvements by going towards better gear.
Basically compensating as much as possible for the attenuation caused by the antenna being indoors, picking up even the faintest signals :wink:


Yes, indoor a small movement can make the difference. In my previous home i placed the antenne in the middle of the room under the room after several tests. Bringing it closer to the window reduced the message rate.

After the move i have it outdoor and it shows the best i can get.

EDIT: I tried to create a picture of my current range and heywhatsthat.

To the left heywhatsthat (blue range set to 12.000 meter elevation) to the right my actual reception how it is shown on Radarbox. Filtering does not improve anything. So it really depends on your location. Heywhatsthat should always be checked while trying to improve it.
Also obstacles which are close to the antenna cannot be compensated with a filter. Concrete is a killer, metal as well

If the roof has metallic panels (popular in some parts of Europe), it will be a killer too. Some roofs have a metallic anti-condensation foil backing.

Even wood and glass has a certain attenuation to the 1.1 GHz signal, so a LNA might be in order to be used there.

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Agreed, more and more modern buildings have some weird things for environmental insulation reasons. I’ve seen some insulation material with a solid metal-foil

I doubt it is my case. Usually builders here use cheapest material possible. In my case roof is made of standard asphalt shingles over plywood.

Buildings are obviously worse than trees, but trees certainly do attenuate, maybe not as much as you would think though.

I have experimented quite a bit with antenna placement, dense trees and attenuation, reflections etc. I have quite the tree lab around my station and figured out which trees are worse (long needle pines, especially when wet). My worst attenuation is north and west/sw (the directions in the photos below).

It’s not so bad for me since most traffic coming my way is from south and east. But in those directions I have up to 14,000 foot mountains… I do get roughly heywhatsthat range east and southeast to the mountains… (antenna is outside, 30 feet up, tucked inside a tree, I’m at 500 ft elevation which helps).

My indoor range was very short. The best results for me came from moving outside with FA antenna or DPD antenna and AirSpy + Uputronics LNA with a higher AirSpy gain that I would have thought. You may benefit from AirSpy with increased dynamic range at higher gain to compensate for attenuation.

8-hour plot