Which one is the best antenna?

Yeah, not having a connector on the Airnav antenna makes it somewhat difficult to get the LNA up there.
Don’t know when i can borrow the lift again, could be interesting to see if it makes a difference moving the LNA. But then i need some sort of PoE i guess.

I’m running gain at 49.6 - I’ve seen other running -10 without problems, i seem to remember his name is Chris.

This is a setting which is normally not used if an LNA/Filter is in the game.
The noise might become to high, but it also depends on the location

I don’t see problems here - I’ll say it’s normal; (Notice: it was set to a much lower value for 15 minuttes, just before the spike at -10 gain for same 15 minuttes) - I did not make a difference on max (or narrow) range. So everything from 32 to 49 seems to work equal on my setup.

Maybe not enough traffic or far away. I am located in the middle of germany with lots of traffic (peak today was 117 aircraft) and lots of aircraft passing by in less than 10km.
The noise level is way to high if set to 48 or higher. -10 gives me a noise of up to 15%.

I am currently running at 42.1 which i am totally fine with. Any higher gain will reduce the number of positions reported

Well, Germany probably has way more traffic - And our setups aren’t the same, so difficult to compare.

If I remove the LNA, and put a Blue filter in-line (FA or RB), my message rate drops to half.

So if you use 49.6 gain with that setup and don’t have signal overload, you have MASSIVE attenuation somewhere in that system.
Or i’m just missing something.

Really strange.

uh, then there’s something strange going on. Any mobile or other networks in range?

Don’t know - But i’m not the only one; Finding optimum gain visually

I have two recievers, two different antennas, two LNA’s, two sticks (four actually, counting the FA Pro stick + in), two Pi’s… How would one bad connection, or defective hardware copy to the other.

I have no idea - Maybe the LNA just do it’s job?

Can you show the graph1090 signal graph?

Might just be that you don’t have many close by aircraft.

Sure - 24H here;
EDIT: At around 18:30-19:00 or so, i replaced the blue sticks with green ones. Thats the strange bounce you’ll see.


Something doesn’t look right to me - not with the gain you said you’re running downstream of that LNA and blue/green radio which are also amplified. I’m with @wiedehopf

And there should not be that big of a bounce between the blue/green radios to boot. They are pretty close to being the same spec. I must be missing something as well.

Yeah there is something off.
I’d say you have an RP-SMA coax or some other connector that’s loose.

(but at least the gain seems to be at a reasonable level judging by the graphs, are you sure about the gain that is used?

pgrep -a dump1090-fa | grep --color=always gain

this should show the gain in use.

There’s no RP-SMA in the setup, all connectors are (gently) heightened with a 8mm wrench - I can see one of the receivers are going at ~10% strong messages, need to lower that a little. Maybe to 48.
Yes, i can confirm previous setting was 49.6. Edited it down now for a test.

Anyway, @chrislfa also seems to be running a high gain with the Uputronics LNA? Maybe he’ll chime in with his experience…
But as said 32 in gain seems to give almost same range.

I just got mine in over the weekend, this is how it looks on the VNA:

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Super! Preciesely tuned @ 1090 MHz, with SWR=1.12

What about dubious claim of 12 dB gain?
Of course gain cannot be measured without very costly equipment, but sided by side trial run with a known antenna such as Fligtaware 26"/66cm antenna will give good idea.

Yeah, I’m not smart enough to calculate the theoretical gain on this half-wave design (pop it into 4nec2? I don’t know how to use that program)- it will for sure be in my next round of comparisons since this unit could live in an outdoor environment if needed - the price is right and it’s properly tuned to boot. It could end up being the new low-cost winner since it’s not very obtrusive either.

Does this antenna has alternating narrow-wide pcb strips along its length? Please see this post in which member JLD posted a design which uses alternating thin-thick wires.


Later addition:
I found that I have already done simulation of alternating thick-thin wire design. It is here:


Any possibility that someone who has one of these antennae can take pictures which shows the design and measurements and which bit of track is connected to which other bit.

Dimensions would be great too.