NooElec ADS-B 8.5cm Antenna Bundle gain JOKE

Isn’t the tip mounted with a screw on the socket? That’s what normally would be the case. You can remove the tip and replace it with a hard wire in the correct length.
That’s what i did without cutting anything on the original

If you’d searched here (or asked), you could have discovered they weren’t worth buying.

Sorry you got caught, but as they say: “When a deal sounds too good to be true …”

NooElec is all over the place with SDR hardware and quite some brand, so I didn´t expect such a lemon at all. I´m about to try support.
Thanks
G.

1 Like

Yeah, their SDRs and LNAs seem quite good.
Not sure why they would sell such lousy antennas.

Yeah - that’s fair. I was surprised to see they put their name to something like that.

I did not purchase the NooElec one. Mine was unbranded one from ebay.
I cut the plastic by a small hacksaw. The NooElec one may be open-able by twisting.

 

I have tried 2 similar to yours. See photo below. The left one is 300mm long (including base) and middle one 200mm long (including base) like yours.
Both performed miserably.

I have removed the bases and using the bases for my DIY antennas (Click here).

 

Unfortunately measurement of gain requires sophisticated and very costly equipment like Anechoic Chamber, signal generator, VNA etc.

 

I am using Flightaware 26"/66cm 1090 MHz antenna and am very satisfied with it. Have no experience of AirNav antenna, so cannot tell anything.

The Airnav antenna performs similar to the Flightaware but with the disadvantage of a fixed cable.

Thanks for your detailed reply!
Re NooElec disassembly: Did some twisting and bending. The top will need some (or more <g>) force to come off.

Re coiled whips: So the whips are connected to signal and the base to ground / shield!? No coils or sth. in the base?

Re measurements: Costly, yeah, what I heard in Andreas Spiess’ YouTube videos.

Is it worth it to try some tweaking? Saw some antenna-related settings in the SW, but can´t find them any more.

Re FA vs. AirNav: Planning to stick the AirNav onto some tube to raise it above the roof-top. (ca. 50 cm)
How much above the roof should the antenna-base be and does the tube material matter?

And: Would you shorten cables? Need a meter or two (depending on model and mounting).
The coiled whip has 3m, the AirNav seemingly 10m.

Thanks again for your help
G.

@gue22 - Definitely worth tweaking. There are some threads around here about those coiled wire antennas. People shorten them up to a specific length and stick the magnet mount on round metal lids to cookie tins or similar. The metal lid gives the antenna a ground plane and shortening up brings it better in tune for 1090. Not sure what to search for but you can optimize those wire coil antennas. When properly tuned, an antenna can help pull in signals of interest while “rejecting” noise.

Lots upgrade to different antennas like a discone or the FLightAware stick. I use the 26” FlightAware stick and it made a huge difference to my range and numbers of aircraft tracked. It was just a connect up and go kind of thing but i did need to also get coax and a proper adapter connector.

If mounting antennas outside, you may also want to look into lightning protection.

Those antenna settings you found - maybe to enable LNA power on the antenna cable? I think the Nooelec’s have that capability.

On shortening cables, it depends. There is per-foot/meter loss in coax and you can improve signal strength, but if the cable isn’t too much longer than needed, it gives you flexibility while sorting out your station. Hand wavy but hard to answer without knowing your coax and the length you are planning to cut.

Regarding the FlightAware vs AirNav antenna… I have both. It seems like the AirNav one are getting me more planes. Note: They are still indoor, placed 20 cm apart, and a lot of trees, buildings, etc. are in the way at the moment. The setup is the same for both. Antenna > Uputronics LNA > AirNav green stick > Pi 4B.
The persistence mode was enabled at the same time this morning to see the difference.

AirNav/RadarBox. Max range is ~155 nm

FlightAware. Max range is ~100 nm

No coils inside base. Only lower part of threaded
brass stud, to which core of coax is soldered
Please see details of base here.

Thanks for the schematic! This simplicity opens up a lot of options. Got the Mag Mount thread already open, but didn´t get around to it.

Possibly stupid q: If I don´t use the base I´d use a ground plane or where do I hook the shield?
I think I remember some VERBALLY grounded radio with a flat antenna (300 Ohms?) cable from my youth (for AM radio?). <grin>
Nothing else than the mains ground??

You´re also confusing me with your Quick Spider article. The RG6 apparently is 75 Ohms and not 50, like the RG174.

And is there a reason that the stuck-in radial part is 21 mm?

Lotsa q!
G.

Guess 150 NM and all kinds of obstacles is some accomplishment in Denmark. What´s your elevation?

I remember my flight instructor wanting me to find the highest “mountain” in Florida, called Mount Trashmore, a cultivated ex-dump, 150 feet “HIGH”. <rofl>

I´m on 300 m with unobstructed view of Alps peaks. :wink:

Cheers
G.

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

1 Like

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.

1 Like