FlightAware Discussions

Ebay 1090 Antenna

Just put a Raspberry pi 30 feet up, but with an Ebay 1090 antenna screwed directly onto the dongle and my range will not exceed 50nm, every time an aircraft reaches 50 nm, the ADSB disappears.

With a bit of cut coax with the shield folded over as a sleeve , I was getting positions of up to 110nm. It’s a dangerous roof to be on, so tomorrow I will remove the Ebay and put up a short length of coax between the dongle and a home made antenna.

Any suggestions?

Sounds like the Ebay antenna might be one of those WiFi antennas masquerading as an ADS-B dedicated one?

Suggest you start out with a simple 1/4 wave GP built on a SO239 antenna socket or a ‘Cantenna’. Search on spider and cantenna should bring up the details.

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I will open it up and check the measurements. Being some 30 feet higher and getting a 50% decrease in range means something is wrong with the antenna and I’ll find out.

Lots of designs to chose from. I like folded dipoles and slim Jims or a multiple element Co-Linear which using TV coax is a gamble as to what the velocity factor is

I wasn’t sure where you were at in terms of antenna construction. My latest coco, built meticulously and using soldered connections, tunes beautifully but at 1024 MHz :frowning: Guessing velocity factor wasn’t as given in the specs.

What do you mean by a “coco” antenna?

A CO(ax) CO(linear) as you mentioned you were thinking of making.

Three Easy DIY Antennas for Beginners

Above thread has following:

  1. STARTER : Stock Whip of DVB-T, placed on a metallic surface (Food Can or Metallic Plate), whip cut to 67mm (1/4 wavelength).

  2. EASY ANTENNA #1 - SPIDER : 1/4 wave Ground Plane built on SO239 connector.

  3. EASY ANTENNA #2 - CANTENNA : 1/4 wave Sleeved Ground Plane. Uses Beer/Pepsi/Coke Can.

  4. EASY ANTENNA #3 - QUICK SPIDER : 1/4 wave Ground Plane. Uses only a one meter piece of coax, without SO239 connector.


I am going to make a “Slim Jim” 2mm copper wire 202 mm long with a
66mm stub 66 mm below the slim jim. All mounted on a bit of 1/2inch pvc

If anyone has done this and noticed a change in length required please let me know. My options were 2mm wire, 6mm and 12.7 mm copper pipe.

After you make the Slim Jim, I suggest you assess how good or bad you have made it. One way to do this is to measure antenna parameters. Unfortunately most DIY hobbyists don’t have costly and sophisticated test equipment required to measure antenna parameters and assess its performance.

The alternative left for hobbyist is to evaluate an antenna by COMPARISON with a reference. There are two easy references available for DIY hobbyists:

Comaparison #1: Determine what maximum possible range can be obtained at a particular location and antenna height, using method described in FIRST POST of thread What is the Maximum Range I can Get?. After this, also obtain maximum range curve of your antenna using VRS, and compare the two maximum range curves.

Comparison #2: Make an easy DIY 1/4 wavelength ground plane antenna (Quick Spider), swap the CoCo by Spider, keeping everything else same (i.e. same same location, height, coax to receiver etc.), and compare results.


Slim Jim has worked for me on other Frequencies,
This one did not appear to work, I replaced it with the bottom of a can of
AeroShell 500 oil with a 1/4 wave on top.
Again, no aircraft, so this time, I recycled the power and the screen jumped alive
with aircraft out to 186nm the record so far, but from Winnipeg, I can see aircraft crossing in and out of Saskatchewan and Ontario while going almost to Fargo in
North Dakota. I would need to go to some very directional antennas into a power divider to push the range out significantly.

Hi ramjet555:
Also consider the FlightAware 1090Mhz antenna : good performance and economically priced. Can purchase antenna through amazon.ca
Many people on the forum have had good success with them.
Mine happily operate near CYAV.

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Maximum Possible Range from your Antenna Location is shown by blue curve in map below.

I have used aproximate location, as I dont know your exact latitude & longitude, but it will be more or less same if you use your exact coordinates.

Yellow curve for flights at 10,000 feet.
Blue curve for flights at 40,000 feet.

Used method described in the thread:

What is the Maximum Range I can Get?

abcd567 Thanks for the diagram. Very nice and very accurate, it is exactly what I am able to see at present to about FL390

I’ve been building antennas all my life and the range I’m getting at present is excellent. I’ve flown in many of the directions and have a practical idea of what range I can get on VHF at various altitudes.
I’m getting over 200 NM in several areas.

Now its the Can of AeroShell 500 Oil with a quarter wave element and its that 1/4 wave sleeve that makes a difference.

The next antenna will be with quality 50 ohm coax, presently I’m using junk RG6U with 67% steel shield that does not solder.

I did pick up 12 chassis mount TV female connectors for making el cheapo’s . Next will come out the N-Connectors, LMR 400 and 6mm copper folded dipoles or other antennas which I expect will add more distance. These will have far higher gain than anything commercial.

I can get 200NM in one direction and my antenna is less than 100ft/30m AMSL.
I have seen a few tracks over PEI from NYC.

The other directions are blocked with buildings and ridges.

If you have no local shielding, you should be able to get out to the heywhatsthat.com distances.
Give it a try for an idea of what you could expect.

As you can see, an aircraft is crossing the 200 nm radius, and the
heywhats that gives a radius about 10 nm less than what I can see
from time to time when an aircraft is at extreme range.
I can see in other directions, it is right on the arc or less.
Overall, its doing slightly better than compared to the prediction.


Glad to know you have achieved, and even crossed the limit predicted by heywhatsthat. The limit predicted by heywhatsthat is slightly conservative. This results in actual maximum range slightly larger than predicted.

Can you please post photos of your “Slim Jim” and “Can of AeroShell 500 Oil with a quarter wave element”? What is dia of Can?

Yes, its a CAN Antenna with a Diameter of 100 mm.

Any large coffee can or similar should be ok.

These things start to look like beer barrels at VHF Frequencies

  1. Why it is called “Cantenna”?

  2. When born?


With the receiver of another service I use this antenna: https://radial.ru/catalog/antennas/vertical/a10_1090/eng/ She and the funnel is dead almost imperceptible, but if you have to put the LNA, hipocrite.