ADS-B DIY Antenna

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jepolch

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I have tried Cantennas with both higher and lower diameters than 66 mm., from as low as 3/4" (20 mm) dia copper water pipe with cap, to 10 cm dia can. Lowering the dia below 66 cm reduces range. Increasing the dia above 66 mm does not show ant noticeable increase, almost same as 66mm Can.

No harm in trying a 7 cm dia beans can, provided it is cut to 69mm height, like pepsi/coke can.
Please see two (2) pictures below.


Picture 1 of 2 - smaller can dia
View attachment 647


Picture 2 of 2 - larger (10 cm) can dia
View attachment 648
I'm getting great reception with my soda can and I won't be experimenting with cans for the time being. After doing so much work building antenna poles out of bamboo and lumber I'm going to abandon those and go with a roof mount. My reception is blocked to the northeast by the house, even though the antenna is 14 feet off the ground. Here's the roof mount I will buy:

http://smile.amazon.com/gp/product/...act_title_1?ie=UTF8&psc=1&smid=A3CICS5XQ6W3LE

I don't remember if I asked you if it's possible to feed two receivers off the same antenna using a coax splitter? If so, which one should I buy. After I put this antenna on the roof I don't want to add more antennas up there if I can help it! :D
 

ab cd

Senior Member
I'm getting great reception with my soda can and I won't be experimenting with cans for the time being. After doing so much work building antenna poles out of bamboo and lumber I'm going to abandon those and go with a roof mount. My reception is blocked to the northeast by the house, even though the antenna is 14 feet off the ground. Here's the roof mount I will buy:

http://smile.amazon.com/gp/product/...act_title_1?ie=UTF8&psc=1&smid=A3CICS5XQ6W3LE
Great! Congratulations.

I don't remember if I asked you if it's possible to feed two receivers off the same antenna using a coax splitter? If so, which one should I buy. After I put this antenna on the roof I don't want to add more antennas up there if I can help it! :D
Yes, it is possible, but splitters add about 5 dB insertion loss. Most splitter won't declare this niether on the name plate, nor in specs, but it is always there.

Since manufacturers/sellers dont declare how much is their splitter's insertion loss, it is hard to say which one is better. Buy one made by some reputable manufacturer even if a bit costlier. Only after inserting it at ground level end of antenna cable and connecting two receivers, you will know if your reception is still good. The amplifier with 13 - 18 dB gain should help in overcoming 5 dB insertion loss.
 

jepolch

Active Member
Great! Congratulations.


Yes, it is possible, but splitters add about 5 dB insertion loss. Most splitter won't declare this niether on the name plate, nor in specs, but it is always there.

Since manufacturers/sellers dont declare how much is their splitter's insertion loss, it is hard to say which one is better. Buy one made by some reputable manufacturer even if a bit costlier. Only after inserting it at ground level end of antenna cable and connecting two receivers, you will know if your reception is still good. The amplifier with 13 - 18 dB gain should help in overcoming 5 dB insertion loss.
The cost of the splitter is certainly more than the cost of making another cantenna. I didn't know about the loss issue. I'm trying to squeeze all I can out of my antennas, so I don't want to insert something that adds signal loss. I'll probably just make another antenna. I actually have everything to make one, including the cable. I was just trying to avoid creating an "antenna farm" on the roof. Having said that, I live out in the country and because of the trees, no one can see my roof anyway. :p
 

ab cd

Senior Member
The cost of the splitter is certainly more than the cost of making another cantenna. I didn't know about the loss issue. I'm trying to squeeze all I can out of my antennas, so I don't want to insert something that adds signal loss. I'll probably just make another antenna. I actually have everything to make one, including the cable. I was just trying to avoid creating an "antenna farm" on the roof. Having said that, I live out in the country and because of the trees, no one can see my roof anyway. :p
With another antenna, you need another amplifier, another power inserter, another dc adapter and another voltage blocker!

Inserters are cheap, $3 to $6. First try a splitter just near receiver, between receiver & power inserter. If things don't workout as you like, order another amplifier, power inserter, dc adaptor & voltage blocker, make another cantenna, and you have 2 independent systems.

http://m.ebay.com/itm/121051029740

http://m.ebay.com/itm/371105165694
 
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jepolch

Active Member
With another antenna, you need another amplifier, another power inserter, another dc adapter and another voltage blocker!

Inserters are cheap, $3 to $6. First try a splitter just near receiver, between receiver & power inserter. If things don't workout as you like, order another amplifier, power inserter, dc adaptor & voltage blocker, make another cantenna, and you have 2 independent systems.

http://m.ebay.com/itm/121051029740

http://m.ebay.com/itm/371105165694
I have a couple of those splitters, now that I see the items you're linking to. But I was thrown off by the frequency range. I know you said that for the amplified it needs to be from 950Mhz up, but for the splitter the lower frequency doesn't matter?

Believe it or not, I have all the hardware for another amplifier, etc., except for the power supply. But, I have a few spare laptop power supplies lying around, so I might have everything - oh wait, except for the amp. I don't have any yet and will get one in the mail - hopefully tomorrow.

Hey, what about plugging two USB RTL-SDR receivers into the same computer? I'm not sure if my Raspberry Pi could handle it (it has four USB ports), but a desktop computer?
 

ab cd

Senior Member
I have a couple of those splitters, now that I see the items you're linking to. But I was thrown off by the frequency range. I know you said that for the amplified it needs to be from 950Mhz up, but for the splitter the lower frequency doesn't matter?
Since I never used splitters with ADS-B, I dont know if lower frequency will make any difference. If you have any splitters, connect and see what is the difference with & without splitter.
Hey, what about plugging two USB RTL-SDR receivers into the same computer? I'm not sure if my Raspberry Pi could handle it (it has four USB ports), but a desktop computer?
Once I tried two DVB-T USB in my windows computers Desktop (XP) and laptop (Win7). Both the computers picked only one of the two USB.

But computer hardware differ widely. Best way to know is to try two DVB-T USB in your computers.
 

jepolch

Active Member
Since I never used splitters with ADS-B, I dont know if lower frequency will make any difference. If you have any splitters, connect and see what is the difference with & without splitter.
I'll give that a try and let you know what happens.

Once I tried two DVB-T USB in my windows computers Desktop (XP) and laptop (Win7). Both the computers picked only one of the two USB.

But computer hardware differ widely. Best way to know is to try two DVB-T USB in your computers.
I can see where it would get confused. Probably best to just use one receiver per computer. :)
 

giacomo1989

Member
Hey, what about plugging two USB RTL-SDR receivers into the same computer? I'm not sure if my Raspberry Pi could handle it (it has four USB ports), but a desktop computer?
I use two on them connected to the same usb external HUB (not powered). They works flawlessy on every computer I have.
Dunno if raspy has enough power. Just try it. (Use a strong external power supply 5v 2A minimum)
 

jepolch

Active Member
I use two on them connected to the same usb external HUB (not powered). They works flawlessy on every computer I have.
Dunno if raspy has enough power. Just try it. (Use a strong external power supply 5v 2A minimum)
Very interesting. How does dump1090 handle the input? Is it possible to see the reception/stats for each receiver? Right now I have a 2.1A power supply and it's enough for the Pi, receiver and USB WiFi minicard. I also have a powered USB hub in case I need it. I only have one RTL-SDR dongle right now. I'll soon get another for Christmas. Thanks for the info.
 

ab cd

Senior Member
.....Today I put my cantenna outdside. It's on top of a 14 foot 2x6. I used a 100 DVD case for the cover........
How you managed with the spindle which is right in the middle of the DVD case, from bottom of the case all the way through to the top of the case?
 

giacomo1989

Member
Very interesting. How does dump1090 handle the input? Is it possible to see the reception/stats for each receiver? Right now I have a 2.1A power supply and it's enough for the Pi, receiver and USB WiFi minicard. I also have a powered USB hub in case I need it. I only have one RTL-SDR dongle right now. I'll soon get another for Christmas. Thanks for the info.
Just choose the receiver with -d option :) -d 0 = dongle 0 -d 1 dongle 1
Then you have to choose different ports (30001 30005 8080...) for each process.
 

jepolch

Active Member
How you managed with the spindle which is right in the middle of the DVD case, from bottom of the case all the way through to the top of the case?
I cut out the spindle to get it out of the way. That also made a nice hole in the bottom to put the cable through. I can't take a picture now because it's on the pole, but I think you get the idea.

I still haven't gotten my amp yet! I was so disappointed when it didn't come in the mail yesterday. I hope it comes today. I'm all set to install as soon as I get it.
 

ab cd

Senior Member
I cut out the spindle to get it out of the way. That also made a nice hole in the bottom to put the cable through. I can't take a picture now because it's on the pole, but I think you get the idea.
Got it, good idea, thanks.

I still haven't gotten my amp yet! I was so disappointed when it didn't come in the mail yesterday. I hope it comes today. I'm all set to install as soon as I get it.
"Patience is bitter, but its fruit is sweet - Aristotle"
 

jepolch

Active Member
Got it, good idea, thanks.

"Patience is bitter, but its fruit is sweet - Aristotle"
Didn't come today, either. :eek:

But I did get one thing accomplished. I built a power supply out of a "wall wart" type power supply and some coax cable. The power supply says 15 VDC, but it's putting out 18.2 volts. I'll take a picture of it later. Just sat down for a little rest.
 

ab cd

Senior Member
Splitter Insertion Loss, declared by at least one manufacturer
- 4.9 dB as "Low Loss".
How much for not-low-loss splitters?

Splitter-Insertion-Loss.jpg
 

ab cd

Senior Member
Didn't come today, either. :eek:

But I did get one thing accomplished. I built a power supply out of a "wall wart" type power supply and some coax cable. The power supply says 15 VDC, but it's putting out 18.2 volts. I'll take a picture of it later. Just sat down for a little rest.
Remember to connect Amplifier's IN port to Antenna and OUT port to power inserter. See image below.

jepolch-RCA D903.PNG
 

jepolch

Active Member
Remember to connect Amplifier's IN port to Antenna and OUT port to power inserter. See image below.

View attachment 659
Thanks for the reminder and for making the great graphic. I have lots of your designs and pictures saved to my hard drive for future reference and so I don't have to go back through this thread again and again. I have gone back over this thread at least a dozen times just to look at your posts and pictures! ;)

The amp didn't come in today's mail. Very frustrating. I did get my roof mount though. I'll be putting my cantenna on top of the roof with this: http://smile.amazon.com/gp/product/B00DJWNYT0/
 
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