ADS-B DIY Antenna

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ab cd

Senior Member
I'm back, and I'm stumped!

A couple of months back I finally got around to raising the antenna onto my tower. Strange things happened....
The higher I had the antenna, the worse the performance was. My 2nd SDR & magmount whip antenna was still setup on the gutter and getting much better performance than the SDR 4m above it.
I removed the amplifier, worse again.
Swapped from the dipole to the pepsi-cantenna+amp. No change.
So I tried another spot, up the mast mounted on the chimney on the roof. Same result...
Switched off all my 2.4ghz wireless gear on the roof, still no better.
I gave up...

Gave it another shot today, built another cantenna. Tested it side-by-side with the magmount, similar/slightly better performance.
This time I decided to try mounting it on the chimney on the OTHER side of the house. Again it seems to be performing worse than the magmount sitting down on the gutter.

EDIT-attached pic:
Top window rpi2 is the cantenna on chimney (approx 4m above ground level). Second window is magmount on the lower gutter (approx 2.2m above ground level).
View attachment 867

Any ideas? :confused:

I'm thinking perhaps something to do with signal reflections from our tin roof?

Tempted to try a HPF or SAW to see if that might improve things.
Hearing your story, I am stumped too!
The power insertor, the amplifier, the coax cable to cantenna are likely candidates causing problem.

First check with BOTH the Amplifier AND Power Inserter removed.
A defective or wrongly connected Power Inserter can also worsen the reception.
A defective or wrongly connected Amplifier can also worsen the reception (antenna conneted to receiver port & receiver/power inserter connected to antenna port).

If that does not work, try changing Coax by a new one. A defective or lossy coax can also worsen the reception.

Can you please post closeup pictures of your power inserter & amplifier showing their terminal markings and indicating which terminal you have connected to what?
 
Last edited:

giacomo1989

Member
I'm back, and I'm stumped!

A couple of months back I finally got around to raising the antenna onto my tower. Strange things happened....
The higher I had the antenna, the worse the performance was. My 2nd SDR & magmount whip antenna was still setup on the gutter and getting much better performance than the SDR 4m above it.
I removed the amplifier, worse again.
Swapped from the dipole to the pepsi-cantenna+amp. No change.
So I tried another spot, up the mast mounted on the chimney on the roof. Same result...
Switched off all my 2.4ghz wireless gear on the roof, still no better.
I gave up...

Gave it another shot today, built another cantenna. Tested it side-by-side with the magmount, similar/slightly better performance.
This time I decided to try mounting it on the chimney on the OTHER side of the house. Again it seems to be performing worse than the magmount sitting down on the gutter.

EDIT-attached pic:
Top window rpi2 is the cantenna on chimney (approx 4m above ground level). Second window is magmount on the lower gutter (approx 2.2m above ground level).
View attachment 867

Any ideas? :confused:

I'm thinking perhaps something to do with signal reflections from our tin roof?

Tempted to try a HPF or SAW to see if that might improve things.
Do you have strong interference source? GSM Cells? DECT phones?
 

ab cd

Senior Member
New conetenna in the works. Now with corporate sponsorship. :D
I made this conetenna a little bit differently. Before cutting out the template shape I stuck strips of clear packing tape on the uncolored side of the metal. This gave the metal a "plastic" feel and it seemed more easy to work with and maybe less susceptible to dents and dings. Instead of gluing the edges together with super glue like I did last time, I put a strip of double sided craft tape (actually there's no tape, it's just a strip of adhesive that comes off a roll) on the inside of the non-tabbed edge and then joined the ends. Once it was cone shaped, I poked holes through three spots with a very thin awl (looks kind of like an ice pick), then followed by drilling the holes the correct size for the rivets (2.4mm). <-- metric :p
Looks Great! The "Corporate marking" :D have enhanced it's looks.
Thanks for "How To Make" tips.
So metric system has started "infecting" USA also :D
 

jepolch

Active Member
I just completed a 5-day test of the 8-legged spider on the 10-foot mast. I let it run that long because the weather's been bad and I didn't feel like going up on the roof. Well, it seems like that's also a good amount of time, because the range plot has stopped growing. Did you ever notice how when you open up VRS you see it update the edges of the range plot? Maybe it's just me, but I always keep my view set on "all altitudes" so I can see the areas that have spread out since the last time I looked. Anyway, I haven't seen any growth for at least a day, so I figure (and this is my point in describing all that!) the range has maxed out.

I just put up the "corporate conetenna, Red Bull version" and I'll leave it up for 5 days ending Friday 1/17/15. I'll bet that after 5 days the difference between the conetenna and the spider will be negligible.
 

ab cd

Senior Member
Using my first RPi connected to TV flashed back my memory to 1970's/1980's, when Sinclair and Commodore 64 computers used TV as monitors. :)
 

jepolch

Active Member
Using my first RPi connected to TV flashed back my memory to 1970's/1980's, when Sinclair and Commodore 64 computers used TV as monitors. :)
I started with a VIC 20 and a TV, later a Commordore 64 ... and a TV. I just got rid of the TV a few years ago and it still worked! Oh, and I still have cartridges for the VIC! :D I have an AIR-1 RTTY demodulator card. I couldn't bare to part with it. I was not a HAM, but a shortwave listener. I still have my Sony radio!
 

ab cd

Senior Member
You know how you get ideas sometimes? How about a spidercone? An 8-sided pyramid.
Your paper model looks promising. Why not make one of aluminum and put on trial run?

You are unlucky that you were born 5000 years late. If you were born during Pharaoh's time, you were sure their chief architect, and all pyramids we see today would have been 8-sided :D
 

ab cd

Senior Member
I have installed PuTTy on my windows desktop, and could successfully access RPi from my Desktop over SSH.
However, the PuTTY showed only console, needing commands to be typed.
I hate typing commands in console...... sudo apt-get install mkdir
.
I love windows "point & click".
Is there a way to run GUI (Graphic User Interface) from SSH? I also installed Cygwin, but that also gives command line console.
 

Turorit

New Member
Hearing your story, I am stumped too!
The power insertor, the amplifier, the coax cable to cantenna are likely candidates causing problem.

First check with BOTH the Amplifier AND Power Inserter removed.
A defective or wrongly connected Power Inserter can also worsen the reception.
A defective or wrongly connected Amplifier can also worsen the reception (antenna conneted to receiver port & receiver/power inserter connected to antenna port).

If that does not work, try changing Coax by a new one. A defective or lossy coax can also worsen the reception.

Can you please post closeup pictures of your power inserter & amplifier showing their terminal markings and indicating which terminal you have connected to what?
Hi mate, thanks for your reply :)

I've removed the amp & injector, seems to be an improvement!
Stupid thing. Strange that it works OK at slightly lower elevation when side-by-side with the magmount on the gutter, yet further up the roof it gets worse.

Whats your signal like if you disconnect the amp and leave the injector, vs removing amp and injector?
Previously when I removed the amp, I still had the injector connected.
I haven't modified my injector at all, perhaps this is the issue? Its a standard DC pass splitter. Unfortunately the way mine is built has no way to open it nicely to modify if neccesary.
Below pic (excuse the mess): Left OUT connector is 14v DC Input. Right OUT connector goes to RTL dongle. IN connector 4m coax to amp.
IMG_20150112_132646 (Large).jpg


Cantenna attaches to ANT connector.
IMG_20150112_133230 (Small).jpg


So we have improvement but still not getting the range I was initially aiming for. More experimenting required, not sure what to try next!
Feel free to take a look at my VRS. You can switch between receiver 1&2 in the menu. http://dorifto.hopto.org:81/virtualradar

@ giacomo1989, there's probably a bit of interference from GSM, DECT & 2.4/5Ghz wifi, though I don't know how much!

Cheers
 

ab cd

Senior Member
@Turorit:
(1) Your amplifier is connected corretly
(2) You are using a Splitter instead of a DC Injector. The Splitter passes almost all you ADS-B signal to your power supply, and very little goes to the DVB-T USB Receiver.

You have either to modify the Splitter and convert it to DC Injector, or buy a DC Injector.
You are right, there is no nice way to open the splitter. I opened it by putting a flat screw driver in the middle of cover, then lightly hammered the screw driver, and the cover depressed inside and edges popped up. I then inserted a small screw driver below the popped up edges and forced the cover open. To convert the splitter to Inserter, you will need a capacitor and an inductor. Please see two (2) picture below:

Power_Inserter_steps-3.JPG



Turorit_IMG_20150112_132646 (Small).jpg
 
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Turorit

New Member
Classic case of user error then!
I figured something like this might happen when I used this splitter, gave it a shot anyway though.

This splitter is a "two halves joined" design, so there is no back cover to pop off. The seam goes lengthways through the F connectors too.
Perhaps this is an excuse to buy a Dremel and attempt to cut the back off :D

Thanks for your pics, I remember them from earlier in the thread. Will give it a shot :)
 

ab cd

Senior Member
Classic case of user error then!
I figured something like this might happen when I used this splitter, gave it a shot anyway though.

This splitter is a "two halves joined" design, so there is no back cover to pop off. The seam goes lengthways through the F connectors too.
Perhaps this is an excuse to buy a Dremel and attempt to cut the back off :D

Thanks for your pics, I remember them from earlier in the thread. Will give it a shot :)
In your splitter, it is not the back. The cover is on the front, on which the label & markings are printed. It is made of aluminum sheet, joined to the case by some adhesive. Put a screw driver in the middle and lightly hammer. The cover will deform, depressing in the middle & popping at edges. You can then put a screw driver under the popped corner and push open. Later when you finish the internal soldering and want to put back the cover, you can straighten it by a flat piece of wood & a hammer.
 

jepolch

Active Member
I have installed PuTTy on my windows desktop, and could successfully access RPi from my Desktop over SSH.
However, the PuTTY showed only console, needing commands to be typed.
I hate typing commands in console...... sudo apt-get install mkdir
.
I love windows "point & click".
Is there a way to run GUI (Graphic User Interface) from SSH? I also installed Cygwin, but that also gives command line console.
Just install a VNC server on your Pi and VNC client on your Windows computer. Then you can use the Pi desktop to work in graphical mode. I have this setup on one of my Pi's, but never use it. I'm an old Unix/Linux guy so I enjoy command line. http://elinux.org/RPi_VNC_Server
 

jepolch

Active Member
Hi mate, thanks for your reply :)

I've removed the amp & injector, seems to be an improvement!
Stupid thing. Strange that it works OK at slightly lower elevation when side-by-side with the magmount on the gutter, yet further up the roof it gets worse.

Whats your signal like if you disconnect the amp and leave the injector, vs removing amp and injector?
Previously when I removed the amp, I still had the injector connected.
I haven't modified my injector at all, perhaps this is the issue? Its a standard DC pass splitter. Unfortunately the way mine is built has no way to open it nicely to modify if neccesary.
Below pic (excuse the mess): Left OUT connector is 14v DC Input. Right OUT connector goes to RTL dongle. IN connector 4m coax to amp.
View attachment 869

Cantenna attaches to ANT connector.
View attachment 870

So we have improvement but still not getting the range I was initially aiming for. More experimenting required, not sure what to try next!
Feel free to take a look at my VRS. You can switch between receiver 1&2 in the menu. http://dorifto.hopto.org:81/virtualradar

@ giacomo1989, there's probably a bit of interference from GSM, DECT & 2.4/5Ghz wifi, though I don't know how much!

Cheers
I'm curious about a couple of things. 1) Why did you remove the outer case from the dongle? 2) Why didn't you plug the dongle directly into the Pi? I wouldn't call it cluttered, actually I think you did a neat job packing all that in a little box.
 
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