Flightaware antenna failed in service


#1

Anyone else had an FA antenna fail on them? All of a sudden the number of aircraft I was picking up dropped dramatically as did the range. After much swapping of dongles, connectors, cables, power supplies and Pi’s, it turned out to be the antenna. I had a spare antenna and when I swapped it in, everything sprang back to normal. …immediate jump from about 30 aircraft to over 100, and range from less than 100NM to over 150NM.

The failed antenna was bought Nov 2015, and installed on the mast on my roof shortly after that. I’m in the Toronto area, so it’s had a couple of years of cold, snow and ice, plus hot summer temps.

There is no noticeable damage on the outside. The connector was clean, dry, and bright. I’d wrapped the connector in self-sealing tape. No signs of water in the connector at all. The heads of the two screws on the aluminum base were quite corroded though.

I had noticed better reception on cold clear days (well below 0C), than warmer damp winter days. Any other ideas?

I guess I’ll have to buy another. I don’t think these things come with any warranty.


#2

Same here, I have on normal days a range of 400-410 Km, at clear days I hit 480 exceptionally 500+ Km. Rain and snowfall, freezing rain and fog, and humidity can significantly affect RSSI. RSSI can experience large variations when temperature fluctuates near 0°C and RH is close to 100%.
RSSI fluctuation in that period could be due to ice/snow on top of the antennas melting into liquid water and/or liquid water (due to condensation or rain) freezing into ice.

Have you managed to open the antenna? Water accumulated inside the antenna can also be a reason, and if the bottom is well sealed you won’t see corrosion (just as idea).


#3

Thanks EmilK. I have not tried to open it… not sure I know how.


#4

Try gently to remove the cap…
If you don’t want to force it then I can try this operation on my antenna if is manageable or not - don’t worry mine is not in use I have a different one


#5

I will give it a try. Mine doesn’t work anyway so there is nothing to lose.


#6

The top is glued on, but a firm twist with pliers will break the glue and you can slide off the cap. The inside was clean and dry. It looks like an empty tube, I’m guessing the antenna elements are in the tube wall. Down at the base you can see a copper center wire surrounded with dielectric foam. The copper is clean and bright with no sign of oxidation. If I had to guess, I’d say that, over time, the wind and temperature changes moves the stick just enough to break whatever electrical connections there are at the base. But I’m open to other ideas.


#7

@Jranderson777
@EmilK

Here is Flightaware 26 inch antenna taken out of outer plastic pipe:


#8

Thanks abcd567. That’s interesting. I can’t see anything like that inside the tube on mine, but it is very hard to see in there.


#9

I gently inserted a piece of dowel and it hits something about 6" down from the top. So there is something in there. How did you remove the tube from the base? I cut away the glue on the outside, and tried twisting the tube, but it is firmly attached.


#10

Well I just cut the tube and removed it. There are three pieces of white foam around various parts of the antenna… the top, the spiral bit and the thicker part below the spiral. Presumably this stops it from rattling around inside the tube. In my case, that foam was soaking wet. I could squeeze water out of it easily. So now we know why the antenna was not working, and why it worked in really cold weather. What we don’t know is how water got in there. The cap was glued on. I had wrapped the base in self-amalgamating tape.


#11

During the day-night cycle, temperature and pressure inside the antenna fluctuates and this way humidity gets inside and condensates on internal elements and remains there, the next cycle brings more humidity.
To go into detail a little bit: as the day begins the temperature inside the antena rises (unlucky colour chosen) and this tendency keeps going during the day, the air inside expands (pressure is temperature dependent) and during the end of the day as the temperature drops, the pressure inside antenna drops too. At a point the pressure is so low that the air from outside gets sucked into the antenna, this time the outside air contains more humidity and so the water gets into a - a first look - sealed antenna. Take into account that this process repeats itself every day even on cloudy days.


#12

Yes, that makes sense. So how do other folks keep the inside dry?


#13

My HOA solved this problem for me.
They dont allow outdoor antenna :smile: