ADS-B DIY Antenna

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ab cd

Senior Member
Comparison of Spider with Cantenna
No amplifier, 5 meters/15 feet cheap quality RG6 coax between Antenna & USB Receiver - for both Spider & Cantenna.

Spider Antenna 4 hrs trial run - maximum range 225nm (range rings are 50nm apart)
DSC03471-R.jpg Spider Antenna 4 hr trial run -Dec21, 2014.png

Cantenna 3 hrs trial run - maximum range 225nm (range rings are 50nm apart)
DSC03477-R.jpg Cantenna 3 hr trial run -Dec21, 2014.png

Note: Spider's coverage screenshot was taken at 9:30 in evening, when number of planes is large, whereas cantenna's coverage screenshot was taken half an hour after midnight, when number of planes drops considerably.
 
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jepolch

Active Member
Comparison of Spider with Cantenna
No amplifier, 5 meters/15 feet cheap quality RG6 coax between Antenna & USB Receiver - for both Spider & Cantenna.

Spider Antenna 4 hrs trial run - maximum range 225nm
View attachment 735 View attachment 736

Cantenna 3 hrs trial run - maximum range 225nm
View attachment 738 View attachment 737

Note: Spider's coverage screenshot was taken at 9:30 in evening, when number of planes is large, whereas cantenna's coverage screenshot was taken half an hour after midnight, when number of planes drops considerably.
Great report! It looks like the spider and cantenna are equal in your test. That's what you would expect, right?

I have been thinking about the problem with my spider antenna and I think I've figured something out. When I made the PL-259 to F type connector I had to push the RG6 very hard into the PL-259 collar. I think all the pushing and twisting may have damaged the insulation or braid inside the cable. I'm going to make another one today and go up to the roof to install it. That is, whenever it stops raining. o_O

Thanks for the information about the coax. Speaking of which, it turns out I may have a large amount of real "commercial grade" coax on hand. I used to have Dish Network and there's a lot of coax leftover that was never removed after I stopped subscribing to the service. I will harvest that coax and replace the end connectors in case any water has gotten inside. I will cut about three feet off the end to make sure I get rid of any contaminated cable. Then I'll add new connectors and I should have about 100 feet of real commercial grade coax.

I "cut the cable", as they say, a couple of years ago. I never watched much TV, but finally I decided I was wasting my money paying for satellite TV. Now if I want to watch something, I just turn on Netflix on my Roku box.
 

ab cd

Senior Member
Great report! It looks like the spider and cantenna are equal in your test. That's what you would expect, right? .......
Not exactly.
The cantenna screenshot was 3 hrs run (9:30pm to 12:30 midnight), mostly low air traffic, as traffic starts to drop after 10pm.

Spider screenshot was for longer period of 4 hrs run (5:15pm to 9:15pm) during high air traffic hours.

When I checked Cantenna VRS at 2am in night (i.e. after 4-1/2 hrs run), the Cantenna maximum range was 250nm, though the number of planes were 1/3rd of what it was at end of Spider test/start of Cantenna test at 9:30pm.

I think I have to repeat the test of both, this time 24hrs run each to cover all ups & downs in traffic, making two test conditions as close as possible.

In nutshell, semi-finals show that the two are close contenders - a tie. We will see who wins after 24hrs finals.:D

I have been thinking about the problem with my spider antenna and I think I've figured something out. When I made the PL-259 to F type connector I had to push the RG6 very hard into the PL-259 collar. I think all the pushing and twisting may have damaged the insulation or braid inside the cable. I'm going to make another one today and go up to the roof to install it. That is, whenever it stops raining. o_O .......
GOOD LUCK. Hope this time you solve the problem for good.
 
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ab cd

Senior Member
I just corrected spelling of "screenshot" in my previous post.

Since o and i buttons on keyboard are side by side, and very small & closely spaced on my phone (from which I typed the last & this message), wen I pressed the o button, the i button clicked, typing 'screenshit' intead of 'screenshot' :D.

Luckily immediately after posting, I noticed it and corrected it. :)
 

jepolch

Active Member
Not exactly.
The cantenna screenshot was 3 hrs run (9:30pm to 12:30 midnight), mostly low air traffic, as traffic starts
to drop after 10pm.

Spider screenshot was for longer period of 4 hrs run (5:15pm to 9:15pm) during higeh air traffic hours.

When I checked Cantenna VRS at 2am in night (i.e. after 4-1/2 hrs run), the Cantenna maximum range was 250nm, though the number of planes were 1/3rd of what it was at end of Spider test/start of Cantenna test at 9:30pm.

I think I have to repeat the test of both, this time 24hrs run each to cover all ups & downs in traffic, making two test conditions as close as possible.


GOOD LUCK. Hope this time you solve the problem for good.
Thanks. It's really making me crazy, because the antenna worked so well for only one day, then stopped altogether!

Good luck with your testing. I know what you mean about comparing the results. Every hour and every day are different in aircraft activity, so it's hard to make an exact comparison, unless you are using two computer/receiver setups!
 

ab cd

Senior Member
Spider & Cantenna comparision: In nutshell, the 4 hrs semi-finals show that the two are close contenders - a tie. We will see who wins after 24hrs finals.:D
 

jepolch

Active Member
I made a new PL-259 to F type male adapter. This one is perfect. If this doesn't fix the problem, the only thing left will be to replace the entire RG6 feedline.
 

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ab cd

Senior Member
I made a new PL-259 to F type male adapter. This one is perfect. If this doesn't fix the problem, the only thing left will be to replace the entire RG6 feedline.
GOOD LUCK! Wish you success with new connector, without need to change the entire feed line.
 

jepolch

Active Member
I went to the roof and put in the new connector. The antenna is working now. Number of aircraft jumped from 35 to 53 after switching from cantenna to ground plane. Of course, the ground plane is six feet higher than the cantenna. One of these days when it's sunny and warmer I'll go up to the roof and move the cantenna to the same height as the ground plane and do a real test.
 

ab cd

Senior Member
I went to the roof and put in the new connector. The antenna is working now. Number of aircraft jumped from 35 to 53 after switching from cantenna to ground plane. Of course, the ground plane is six feet higher than the cantenna. One of these days when it's sunny and warmer I'll go up to the roof and move the cantenna to the same height as the ground plane and do a real test.
Congatulations.

Waiting for you to raise Cantenna to same height as Spider. Thanks for agreeing to compare the two antennas at same height. I know it is hard for you to go up & down the ladder.

More than one person carrying comparison test gives more reliable conclusion. 2 testers are better than 1, and 3 testers are better than 2. I am looking for one more volunteer to participate in this comparison
 
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jepolch

Active Member
Congatulations.

Waiting for you to raise Cantenna to same height as Spider. Thanks for agreeing to compare the two antennas at same height. I know it is hard for you to go up & down the ladder.

More than one person carrying comparison test gives more reliable conclusion. 2 testers are better than 1, and 3 testers are better than 2. I am looking for one more volunteer to participate in this comparison
I'll be glad to do it. I'm very curious myself.

When I opened the PL-259 adapter I found the insulation was split and some small bits of braid were loose. I just don't understand why that antenna worked - and worked great - for 24 hours. It's a mystery.
 

ab cd

Senior Member
.....When I opened the PL-259 adapter I found the insulation was split and some small bits of braid were loose......
The main reason I like Cantenna is its simplicity.

Workmanship for Cantenna does not require difficult coax connection and soldering skills.

Cantenna can be constructed with readily availble and almost free materials, with minimum of skill. It does not require special connectors like SO-239 & PL-259, which are avaiable only from speciality stores like Radio Shack, or should be ordered on line involving higher cost and shipment time.

Cantenna requires only an F type female barrel connector, which is commonly available, and extremely cheap.

F barrel connector female.jpeg

Any common can like pepsi or beans or coffee or tuna can be used, as long as its dia is larger than say about 65mm, and length longer than 69mm.

cans.jpg

For drilling the hole in can's bottom, a drill machine is required. If someone does not have a drill machine, he can make the hole by a thick nail & hammer.

Cutting length of can to 69mm optimizes the performance, but if some one does not have tin snips and the can is hard and difficult to cut like a beans can made of tinned iron sheet, it can be left uncut, without serious degradation in performance.
Cantenna - Beans can.jpg

Coax connection requires only simple screw-on F connector, very cheap and very commonly available everywhere, and can be fitted to coax easily without requiring any special skill or special tools.
F male screw on.jpeg
 
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giacomo1989

Member
I've bought and installed an Inline amplifer to my cantenna. It's a 47-2400 Fuba OSV110 with 16-20db gain.
I know it isn't the best option but coverage suddently became bigger after the installation!

I'll report back. I paid it only 5 euros! (tax included in the shop!)
 

ab cd

Senior Member
I've bought and installed an Inline amplifer to my cantenna. It's a 47-2400 Fuba OSV110 with 16-20db gain.
I know it isn't the best option but coverage suddently became bigger after the installation!

I'll report back. I paid it only 5 euros! (tax included in the shop!)
Lucky to have success with an amplifier which has lower frequency as low as 47 MHz!
For some strange reason, this type has failed with several hobbyists.
 

giacomo1989

Member
Lucky to have success with an amplifier which has lower frequency as low as 47 MHz!
For some strange reason, this type has failed with several hobbyists.
Then fact is maybe that it's designed to amplify dvbt and sat signals. On the specs they say also 950-2400. Maybe it has two different amplifiers for both bands?
 

ab cd

Senior Member
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ab cd

Senior Member
I'll be glad to do it. I'm very curious myself.
Thank you.

When I opened the PL-259 adapter I found the insulation was split and some small bits of braid were loose. I just don't understand why that antenna worked - and worked great - for 24 hours. It's a mystery.
Why it worked for 24 hrs & then suddenly died?: It seems the insulation inside connector got damaged during screwing-in the coax to connector, but not fully. It took 24 hrs expansion contraction due to temprature fluctuation plus mechanical stress due to wind to finally break it down to a short.

Why it worked great during those 24 hrs?: Due to very favourabe weather and atmospheric condition on that day
 
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