ADS-B DIY Antenna

Status
Not open for further replies.
trigger said:
I was reading up about folded monopoles to see if I could build one for ADS-B. I came across this http://www.eham.net/ehamforum/smf/index.php/topic,95373.0.html
Knowing that jepolch loves cutting up cola cans so I thought I'd challenge him to build this one :cool:

You mean this one?

Maybe this one?
folded monopole.PNG


Or this one?
Folded Monopole.JPG
 
Last edited:
Hi all! New to the forums here. Seems like a really nice community!

Following a link someone posted to eHam, i found another link to this: http://ads-b-antenna.blogspot.com

Reading the description and the models he has run, this seems like a pretty nice optimized antenna. I'm not sure if the price of 25 euros includes shipping to the US or not, but I'm tempted.

Interested in opinions from those more knowledgeable than I.
The antenna seems very tempting. Never came across this design before.
Cannot say how it will actually perform. Someone who has used it can tell. Maybe in the forum from where you got this link some one has tried it. One option is to dig through that forum's posts to find out.
 
Which type of antenna is good?

TYPE 1
Physically small & simple antennas like 1/2 wave Dipole, Spider, Cantenna etc have advantage of having 75 ohm impedance hence perfect impedance match and good SWR without any need for phasing & impedance matching. These antennas are not sensitive to accuracy, and a few mm error will not substantially degrade performance, hence these are good for DIY novice. However these have disadvantage of low gain (of the order of 1.5 to 2 dBi), hence need an amplifier to cover for weak signals from distant plane and to cover for attenuation in coax feed line.

TYPE 2
Physically larger, multi-element antennas like CoCo, Franklin, Coiled Whips etc have high gain (of the order of 4 to 9 dBi), so give better results compared to tiny ones listed above. However they have biggest disadvantage that these should be accurately designed and accurately constructed to get proper phasing & impedance match. A few mm inaccuracy in design or fabrication completely knocks down these antennas and pushes these from excellent to poor category. The accuracy condition is met in factory environments with computer-aided design, model testing, fabrication templates & jigs, and final testing & adjustment by test equipment. The accuracy condition is very difficult to meet in DIY situation. Hence the failures.

For a new DIY enthusiast, it is best to start with simple tiny ones (type 1) with amplifier added. At later stage the DIY enthusiast can try the more sophesticated ones (type 2)
 
Yes, reply #11 in the post. There are some NEC files attached to the post so now ab cd has sorted his Pi out he will have more time to do some modelling ;)
ads-bview-png.1012

1. The files are in EZNEC format. I don't have EZNEC. I use 4nec2 for modelling.

2. What I can make out from discussions is that they are modelling a ground plane fed through a hairpin for increasing the impedance (funny).
The view in their drawing is badly chosen. It is hiding the hairpin. I have drawn another sketch which fully shows the hairpin.

Dipole Fed Through Hairpin.PNG
 
Yes, reply #11 in the post. There are some NEC files attached to the post so now ab cd has sorted his Pi out he will have more time to do some modelling ;)
ads-bview-png.1012
Is that just a disk with a whip? Might be good, but not very challenging. It's basically a cantenna without the can (just the lid). :) Unless I'm missing something.

Here's the antenna I've been building tonight. I have all the straight segments and one of the coils cut. One more coil to wind tomorrow. Making the coils is the most time consuming part, except for the soldering, probably. It's huge compared to the antennas we usually make. http://www.multimode.fr/articles/realisations/antenne-verticale-colineaire-1090-mhz/
 

Attachments

  • antenne_1090_sans_protection.jpg
    antenne_1090_sans_protection.jpg
    11.1 KB · Views: 103
Excellent! I've been feeding FlightRadar24 and I've never seen my stats like that. If I go to my account and click on My Feeds, I just get this:
  • Radar: T-KRDU17 Status: Online Last upload (~5min): 2015-02-01 03:48:16
No nice graphs like you have. Is there anything I need to set up to see that?

Edit: I figured it out. I've never looked at that page before. I've just been looking at VRS and my FlightAware page.
 

Attachments

  • fr24stats.jpg
    fr24stats.jpg
    91.2 KB · Views: 48
Last edited:
1. The files are in EZNEC format. I don't have EZNEC. I use 4nec2 for modelling.

2. What I can make out from discussions is that they are modelling a ground plane fed through a hairpin for increasing the impedance (funny).
The view in their drawing is badly chosen. It is hiding the hairpin. I have drawn another sketch which fully shows the hairpin.

View attachment 1024
Hi guys,
This is what I understand.
The vertical is attached to the disk a couple of mm away from the centre and is connected to braid. The hairpin connects the core to the vertical. Someone has calculated that the hairpin length has to be 10.8mm

See here although still not a good photo it shows the attachment of the hairpin. The vertical is NOT attached to the centre but offset. http://g7mrv.blogspot.co.uk/2014/03/an-ads-b-receive-antenna-from-scrap-2nd.html

Read through the whole post especially #21 http://www.eham.net/ehamforum/smf/index.php/topic,95373.0.html
 

Attachments

  • Untitled 1.jpg
    Untitled 1.jpg
    10.2 KB · Views: 39
Last edited:
Hi Bram!
If you install your antenna outdoors above roof, your range will increase greatly.
The ADS-B reception is line of sight. It is limited by curvature of earth.
The maximum range limit due to curvature of earth is about 250nm/500kms if the terrain is nearly flat and there are no high obstructions like mountains.

There is a very interesting and useful site which plots maximum range from any location by entering that location's coordinates (Latitude & Longitude) and height of antenna above ground. You can check for your location by following steps:
1. Go to http://HeyWhatsThat.com
2. Click tab "New Panorama" on top left of the page
3. In New Pnorama page, enter your Latitude, Longitude, and antenna height above ground
4. Click button "Submit request" and wait for a minute or two for map to generate.
5. At bottom right of the generated map enter two flight levels, then click "up in air" button on top right of the map. The mx range rings for two flight levels will be generated.
6. Zoom out if you dont see the max range curve which may be outside map boundries.

I have generated a max range curve for planes at 30,000 feet & 40,000 feet, with antenna at 25 feet (8 meters) above ground level.
I have taken the location of antenna at the center of city of Almere in Netherlands. Please see below:

View attachment 977

Hi All,

The Franklin Antenna is outside now ,

Regards Bram


Screen Shot 2015-02-01 at 15.32.38.png


Screen Shot 2015-02-01 at 15.48.21.png
 
Excellent! I've been feeding FlightRadar24 and I've never seen my stats like that. If I go to my account and click on My Feeds, I just get this:
  • Radar: T-KRDU17 Status: Online Last upload (~5min): 2015-02-01 03:48:16
No nice graphs like you have. Is there anything I need to set up to see that?

Edit: I figured it out. I've never looked at that page before. I've just been looking at VRS and my FlightAware page.

Just 162nm?
 
Hi guys,
This is what I understand.
The vertical is attached to the disk a couple of mm away from the centre and is connected to braid. The hairpin connects the core to the vertical. Someone has calculated that the hairpin length has to be 10.8mm

See here although still not a good photo it shows the attachment of the hairpin. The vertical is NOT attached to the centre but offset. http://g7mrv.blogspot.co.uk/2014/03/an-ads-b-receive-antenna-from-scrap-2nd.html

Read through the whole post especially #21 http://www.eham.net/ehamforum/smf/index.php/topic,95373.0.html
Here's another picture that shows it more clearly. The dimensions are written on the disk.
 

Attachments

  • 20140304_213357.jpg
    20140304_213357.jpg
    122.2 KB · Views: 99
Here's another picture that shows it more clearly. The dimensions are written on the disk.
Hi jepolch, I'm not sure my diagram above is correct. I think the vertical is only connected to the ground plane. The hairpin seems to be connecting the ground plane to the centre core of the plug.
 

Attachments

  • Untitled 1.jpg
    Untitled 1.jpg
    10.5 KB · Views: 33
Hi jepolch, I'm not sure my diagram above is correct. I think the vertical is only connected to the ground plane. The hairpin seems to be connecting the ground plane to the centre core of the plug.
Here's what's written on the second link in your post. It sounds different from what you drew, and also from the picture I included:

Imagine a vertical rod mechanically mounted and grounded to the groundplane. The coax connector is next to it, and a conductor from the center parallels and taps onto the vertical element some distance up.
 
Still not sure I understand the geometry of this :confused: When you've built it and found that it works brilliantly, please post some detailed instructions and photos ;);)
 
Still not sure I understand the geometry of this :confused: When you've built it and found that it works brilliantly, please post some detailed instructions and photos ;);)
I don't know why everyone thinks I'm building it! :) As I said above, it doesn't look very challenging.

I just finished building a colinear based on the attached pic. I am tired of messing with it now, so I'll take pictures of it tomorrow. It came out really nice. And it feels fragile, because it's so spindly. I will get some 1/2 inch PVC tube to put it in.
 

Attachments

  • ADS-B-antenna-drawing.gif
    ADS-B-antenna-drawing.gif
    25.8 KB · Views: 109
Status
Not open for further replies.
Back
Top