FlightAware Discussions

NooElec ADS-B 8.5cm Antenna Bundle gain JOKE

My elevation is ~300 feet over sea level - Denmark is quite flat though.

I’ll get better performance, when I get the antennas up. But lucky as I am, looked for a mast/pole at 11 meter, but it was sold already. I’ll find another one :slight_smile:

Use any of these to connect the shield of coax:
In first one, the SO-239 connector and radials form ground-plane, in second one the tuna-can lid acts as ground-plane.

NOTE:
The “ground” and “antenna ground-plane” are two different things.
The “ground” uses rods driven into ground.

 

The tin can looks like from “The Day After” - if there weren´t the cozy, clean houses in the background.

Thanks, ground plane vs. ground was clear. The question was how weird would it be to use the mains plug ground.

And that you use a 75 Ohms RG6 when else is 50. No reflections?

Just tried the NooElec vertically as suggested with no success. Sent the pic to support.

BTW: Would I need to restart dump1090-fa (for AGC) when I change antennas on the fly?

Thanks again
G.

In transmitters this mismatch can cause reflection of power which are in the range of few watts to several hundred watts, and to compensate one requires a transmitter with larger power output, which is a costly affair.

In receiving senario like ours, the power levels are in mili or even micro watts, and any loss can easily be compensated by a LNA which is not costly (FA ProStickj has one builtin with 18 dB gain). In terms of dB, the loss caused in each transition from 50 to 75 or 75 to 50 is only 0.177 dB which is easily compensated by Gain of Dongle and/or LNA

The receiver DVB-T is actually designed for TV reception (DVB-T = Digital Video Broadcast - Terrestrial). As the TV systems use 75 ohms Antenna with 75 ohms TV Receiver, the DVB-T’s input impedance is 75 ohms, and NOT 50 ohms.

SUMMARY: Dont worry, be happy. Just ignore the 75 vs 50 ohms issue

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As far as i know, Flightaware and Flightradar as well are delivering different antennas depending on the country.
In Germany the kit is shipped often with the well known antenna from Jetvision.

Yeah I think a lot of the old-skool HAM guys are more concerned about Ohm’s Law than they should be for a receive only system for ADS-B. To boot, I don’t think many here have very long cable runs (like 100M or more) so the perceived mismatches really don’t have an impact as they would for an Rx/Tx setup.

Being more concerned about keeping the components running cool and without interference should be top priority when putting a system together, don’t sweat the small stuff. Get the antenna as high as feasible for your location and the rest is back-fill.

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Sorry for the confusion. I bought the antenna directly from Jetvision, just refered to it as FlightAware, since they use it.

For everyone´s info:
NooElec support was quick to reply, but now they´re acting stupid by requiring a screenshot with the zero planes I get with their antenna, not sufficing with the one I sent them with the coiled whip mounted.

Refusing to change again to prove nothing.

But I just tried to stick a 68x1mm wire directly into the vertically mounted FA, here with the coiled whip


but 1 mm seems too thick. Need to try a wire from an RG6 tomorrow.

Good night Just saw I forgot to post this with all the NooElec ballyhoo. Good morning
G.

RG6 core wire has diameter of 1 mm, so wont go into hole of ProStick connector.

Straighten a small paper clip. It will fit the thin hole of ProStick plus. I have done it.

 

Radials from straightened paper clips
2019-01-07 21.44.41

After the NooElec support nonsense demand of an empty plane list in PiAware SkyAware when I use their antenna (Doesn´t show anything that I use their antenna or specific reception data) I think I found some culprit when I changed antennas several times:

I had two distinct coverage experiences with the coiled whip:
For some days I had a poor coverage of up to 160km and after some tinkering I had up to 400 km. (e.g. Sunday)

The antenna position was practically the same. (see attic picture)
The difference seems to be that I just screwed the SMA tighter than before.

Maybe the connector male pin just gets close and doesn´t make real contact when not screwed with some considerable force.

Wadayathink?
G.

I think you could use some more free-space around your antenna, no matter what you end up using. I’m willing to wager that you will see better results since surroundings have a direct effect, especially solids.

I pasted some side-by-side tests that included one of them coil antenna’s and they are truly trash. Grab an FA antenna and be done with brain-bleeding that portion of things, you will save in the end, money and heartburn. (I don’t work for FA or get anything by recommending their antenna, I just haven’t come across a cheaper alternative that performs as well, so until I do, I’ll continue to recommend them)

The Flightaware Antenna with Plastic Pipe Removed

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Best antenna to date for me :grinning:

Thanks, as mentioned above I already ordered a FA, AirNav, Jetvision or whatever clone Radarbox ships here via Amazon and I have it in my head how to mount it on top of the roof.

Sadly this was the first article where Amazon didn´t tell me a shipping estimate at all and Radarbox didn´t answer for 3 business days. (The mail bounced.)

Still, I´d like to nail why the NooElec barely works and why I get two very different results from the coiled whip, seemingly depending how tight I screw the SMA, cuz the position remains the same ±2cm.

Cheers
G.

You have the SDR very close by which is sth to avoid.

The SDR itself is a source of interference that can couple back through the antenna.

A loose SMA could account for the change in reception.

Also having the antenna positioned differently on that metal plate could significantly affect the outcome.
Then at the top of the antenna … 2cm there could make quite a difference because i’m sure there are nails exactly where the wood beams meet.
Get it to close to a nail at the tip of the antenna … tune goes completely off.

In other words, impossible to determine anything when your setup is that variable.

I have doubts regarding your cabling show in the picture. How did you fix the Raspberry? To me it looks like it stresses the USB connector towards the FA stick

Thanks for the input, but this is a Pi Zero W, I bet under 50 grams and the micro-USB-B to USB A needed is bigger, bulkier and heavier than the Pi.

This second major setup variant was to test the NooElec vertically without bending its knee, directly on the FA, with the Pi NOT on the same horizontal plane as the antenna – as suggested earlier.
Cheers
G.

Oh i see…

Yeah that’s better because the SDR isn’t backfeeding into the antenna as much.
Having the knee bent means you get lots of SDR noise back fed …

But they remain a joke no matter the orientation.

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With the NooElec and the vertical setup out, and waiting for the AirNav 66cm, I´ll check some coil whip variants according to your suggestions in the prior message.

First up: Move stick and Pi away from the antenna and see what other factors may influence antenna perf.
Thanks
G.

Even 50 gram of weight can cause issues. I would consider to take away the force on cable, connector, stick, raspberry independent from it’s weight