ADS-B DIY Antenna

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ab cd

Senior Member
I found this simple and easy to make antenna from another forum.
The Range mentioned in this post (200nm) is remarkable for such a simple antenna.


"Mine is made with 33cm unshielded TV coax and as a ground plane the bottom of a thunafish tin. More than 200nm."
tuna fish can monopole_9ame3ehe.jpg


 
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Turorit

New Member
After you have made and tried various antennas and have comparaed their performance, do one more project: add an inline amplifier.

The amplifier greatly enhances range of every antenna.

To make inline amplifier work, you will also need a dc power supply (dc adaptor) and power inserter,

The amplifier, dc power supply & dc inserter each will cost from $5 to $15 depending on make and the seller.
Its definately on the list :)
I already have an amp from my sat TV days, a couple of splitters laying around that I can repurpose for the injector & a few misc laptop PSUs which should be around the 15-18v mark.
I'm all set for things to do this long weekend :D

I'm looking at connecting the antenna & splitter directly to the r820t receiver with no coax feeder. Have you noticed any issues with frontend overload/the need for a saw filter in this configuration?
I'm running my receiver from a raspberry pi using dump1090 with default gain settings (not sure what they are)

Cheers
 

ab cd

Senior Member
Its definately on the list :)
I already have an amp from my sat TV days, a couple of splitters laying around that I can repurpose for the injector & a few misc laptop PSUs which should be around the 15-18v mark.
I'm all set for things to do this long weekend :D

I'm looking at connecting the antenna & splitter directly to the r820t receiver with no coax feeder. Have you noticed any issues with frontend overload/the need for a saw filter in this configuration?
I'm running my receiver from a raspberry pi using dump1090 with default gain settings (not sure what they are)

Cheers
Thanks for detailed info about your project.
If you see photographs of my various antennas which I have posted, you will find that my antennas are directly connected to "IN" port of the amplifier, without any coaxial cable. The coaxial cable starts from the "OUT" port of the Amplifier.
I never felt any issues of front-end overload or need for a saw filter.
If someone is close to a cell phone tower, a saw filter maybe required.
 

ab cd

Senior Member
I have run simulation of two CoCos, varying element length in steps, from less than standard length** (see below) to more than standard length, plotting gain, swr, and impedance against element length. Results show that antenna SWR/impedance vary considerably with relatively small changes in element length.

**Standard element length = 1/2 x 275 x 0.83 = 114mm.
Blue circle shows SWR for standard element length (114 mm).
Red circle shows element length where SWR is minimum.


4-element RG6 FPE ins 0.83 Vf
Rev2-TABLE- Variable element length CoCo (4 elements) from RG6 VF 83 percent.PNG




8-element, RG6 FPE insulation, 0.83 VF
Rev2-TABLE- Variable element length CoCo (8 elements) from RG6 VF 83 percent.PNG
 
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ab cd

Senior Member
Rein the Wild DIY CoCo

Since the SWR of CoCo is very sensitive to element length, in DIY situation which lacks proper test equipment, it rarely happens that a CoCo with reasonably low SWR is made. As a result the maximum range in most cases is moderate to poor.

Changing the length of elements in small steps is one option to improve SWR/Range, but very tedious, and will make most DIY enthusiast to quit. Further it is not known, in any particular situation, weather to increase or to decrease the length of elements.

The other option is to use an impedance matching network with VARIABLE capacitor or VARIABLE Inductor, and try to achieve matching by adjusting the variable capacitor/inductor. This is similar to tuning an AM/FM Radio by turning its tuning knob. This is far more easy than trimming the elements, and suits DIY enthusiasts.
 

Turorit

New Member
So I've been meaning to upload some pictures but I've been lazy!
I've built both the dipole & pepsi-can antenna and had them running on the amp. So far it seems the dipole has a better range than the cantenna.
I'm waiting on a few more parts from ebay, then I'll be putting my raspberry pi, rtlsdr dongle and amp power injector into a waterproof box at the top of my tower (photos down the page). Hopefully this will yield a better maximum range.
Unsure yet how the rpi & dongle will go with temperatures at the top of the tower, especially in our 40'C summers.

My aim is to be able to receive ADSB aircraft from west of Port Lincoln on the Eyre Peninsula, which requires a 300km receive range. Currently the best I'm doing is about 200km which is just shy of the east of Port Lincoln.

Baseline range plot - e4000 tuner with magmount antenna, approx 2.5m above ground sitting on the gutter. Range is approx 160km.
e4000 magmount on gutter.PNG

Baseline range plot with r820t tuner & magmount. Range increased slightly to.
r820t magmount gutter3.PNG

Construction of dipole & resulting range plot. Dipole elements in picture hadn't been cut to size yet.
IMG_20141003_214029nopm (Small).jpg r820t amp dipole 4days.PNG

Construction of pepsi-can antenna (using a beer can) & resulting range plot.
IMG_20141006_175259 (Small).jpg DSC02680 (Small).JPG r820t beercan w amp 3days.PNG

Receiver & injector - Using a old laptop power supply
IMG_20141005_213107 (Small).jpg

Antenna location - on the back of the house in a plastic bag, taped to a piece of bamboo.
DSC02681 (Small).JPG

A picture of all my other antennas and radio tower. Tower has Amateur 2m & 70cm yagi. Chimney pole has 4x antennas for 2.4&5ghz WiFi-long distance community wireless network. Also a airband J-pole and a 2m/70cm J-pole.
DSC02779 (Large).JPG

Thanks for looking :)
D.
 
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ab cd

Senior Member
So I've been meaning to upload some pictures but I've been lazy!
I've built both the dipole & pepsi-can antenna and had them running on the amp. So far it seems the dipole has a better range than the cantenna.
I'm waiting on a few more parts from ebay, then I'll be putting my raspberry pi, rtlsdr dongle and amp power injector into a waterproof box at the top of my tower (photos down the page). Hopefully this will yield a better maximum range.
Unsure yet how the rpi & dongle will go with temperatures at the top of the tower, especially in our 40'C summers.

My aim is to be able to receive ADSB aircraft from west of Port Lincoln on the Eyre Peninsula, which requires a 300km receive range. Currently the best I'm doing is about 200km which is just shy of the east of Port Lincoln.

Baseline range plot - e4000 tuner with magmount antenna, approx 2.5m above ground sitting on the gutter. Range is approx 160km.
View attachment 563

Baseline range plot with r820t tuner & magmount. Range increased slightly to.
View attachment 564

Construction of dipole & resulting range plot. Dipole elements in picture hadn't been cut to size yet.
View attachment 565 View attachment 566

Construction of pepsi-can antenna (using a beer can) & resulting range plot.
View attachment 567 View attachment 568 View attachment 569

Receiver & injector - Using a old laptop power supply
View attachment 570

Antenna location - on the back of the house in a plastic bag, taped to a piece of bamboo.
View attachment 571

A picture of all my other antennas and radio tower. Tower has Amateur 2m & 70cm yagi. Chimney pole has 4x antennas for 2.4&5ghz WiFi-long distance community wireless network. Also a airband J-pole and a 2m/70cm J-pole.
View attachment 573

Thanks for looking :)
D.
Your range is less than it should be with an amplifier and not very long coaxial cable.
The first & foremost limitation comes from the terrain. Even the best equipment cannot increase range beyond the limit set by terrain. Only antenna height can increase the range limit to some extent.

I have pltted the maximum range achieveable at your location with antenna height 20 feet above ground, Two range curves are plotted, the blue one for planes flying at 40,000 feet & orange one for planes flying at 20,000 feet,

You should be able to achieve this range. Your home is blocking signal in some directions with antenna at current height/location. When you will mount your antenna on the tower, above roof line of your home, range should increase to some extent.

Please see your Maximum achieveable Range plot based on your terrain & 20 ft antenna height.

Turorits Range.PNG
 
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ab cd

Senior Member
THE MAGIC OF ANTENNA TUNER

4-Element CoCo made of coax RG6 FPE insulation 0.83 VF element length 114mm

(1) Without Impedance Mtching
SWR=5.03, impedance = 181-j181 ohms - heavily reactive and far from 75 ohms


Without Impedance Matching-High Pass-variable length CoCo 4 element FPE insulated.PNG



(2) After inserting an Antenna Tuner (a matching L-network) at the point where feed cable meets the CoCo
SWR=1.01, impedance = 75.7-j0.75 ohms - almost 75 ohms pure resistive


Impedance Matching-High Pass-variable length CoCo 4 element FPE insulated.PNG

.
 

ab cd

Senior Member
.....I've built both the dipole & pepsi-can antenna and had them running on the amp......
I suggest a little improvement: apply a drop of hot-melt glue or other adhesive to secure loose limbs of cantenna & dipole.
The glue/adhesive will also prevent rain water/ moisture entering from these points.

See images below:

IMG_20141003_214029nopm (Small).jpg




DSC02680 (Small).JPG
 

Turorit

New Member
Your range is less than it should be with an amplifier and not very long coaxial cable.
The first & foremost limitation comes from the terrain. Even the best equipment cannot increase range beyond the limit set by terrain. Only antenna height can increase the range limit to some extent.

I have pltted the maximum range achieveable at your location with antenna height 20 feet above ground, Two range curves are plotted, the blue one for planes flying at 40,000 feet & orange one for planes flying at 20,000 feet,

You should be able to achieve this range. Your home is blocking signal in some directions with antenna at current height/location. When you will mount your antenna on the tower, above roof line of your home, range should increase to some extent.

Please see your Maximum achieveable Range plot based on your terrain & 20 ft antenna height.

View attachment 574

Thanks for the plot :)
I'm quite interested to see how it will perform once above the roof line. I still find it quite impressive how well it works in its current setup.
I've considered putting the antenna on the tower & running a 15-20m RG6 feedline back to the receiver. I calculated the loss to be about 4db for 1090mhz using RG6, so it seems like a bit of a pointless exercise as any gains will be lost in the return line.

RE glue in your subsequent post, both antennas do have a drop of hot melt, it just wasn't shown in the pictures. Thankyou for pointing it out though!
 

kyle macarthur

New Member
Gentlemen,

I have been lurking here for awhile, but tonight I assembled the parts I purchased on eBay to built my amplifier. Despite my horrible soldering skills, everything went together without a hitch. And, the moment of truth as I plugged in my wall wart didn't result in any blown fuses.
The result has been pleasant. My RTL1090 has gone from an average of 2-3 lights on the packet rate to an average of 4-5.

I have a DIY omni antenna around 25-feet in the air (it's the green one shown in the photos people post), but I do have a 5/8 vertical wave that seems to "pull in" more packets, but not the seemingly wider footprint of my current antenna. I will double-check it again tomorrow, as I switch them.

Overall, very pleased.
 

ab cd

Senior Member
Gentlemen,

I have been lurking here for awhile, but tonight I assembled the parts I purchased on eBay to built my amplifier. Despite my horrible soldering skills, everything went together without a hitch. And, the moment of truth as I plugged in my wall wart didn't result in any blown fuses.
The result has been pleasant. My RTL1090 has gone from an average of 2-3 lights on the packet rate to an average of 4-5.

I have a DIY omni antenna around 25-feet in the air (it's the green one shown in the photos people post), but I do have a 5/8 vertical wave that seems to "pull in" more packets, but not the seemingly wider footprint of my current antenna. I will double-check it again tomorrow, as I switch them.

Overall, very pleased.
CONGRATULATIONS!

Posting a few photos of your system (amlifier, power inserter, antenna etc) will help us to enjoy your success.
 

kyle macarthur

New Member
Well, here they are... in all their glory.

Notice how I screwed the splitters to a piece of wood. It cleans up the project a bit, and it sits nicely on the window ledge.

The map shows how my antenna is pulling in signals from across the region. I understand my geography is VERY flat, so this may aid my attempts. I may swap out my current antenna for my 5/8 tomorrow, depending on the weather. Hope you like the photos...

Kyle
 

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ab cd

Senior Member
Well, here they are... in all their glory.

Notice how I screwed the splitters to a piece of wood. It cleans up the project a bit, and it sits nicely on the window ledge.

The map shows how my antenna is pulling in signals from across the region. I understand my geography is VERY flat, so this may aid my attempts. I may swap out my current antenna for my 5/8 tomorrow, depending on the weather. Hope you like the photos...

Kyle
Nice work, very neat & crafty. Thanks for sharing the photos.
 

ab cd

Senior Member
Comparison of three versions of 4-element CoCo made of RG6 coax FPE insulation, VF=0.83

(1) Max Range - Basic CoCo (4-elements, each element 114mm RG6)
CoCo-4-Element-RG6-114mm-24hrs run-30 Oct 2014-R1.jpg




(2) Max Range - Basic CoCo + 1/2 element shorted at top

CoCo-4-Element-RG6-114mm-24hrs run-31 Oct 2014-R1.jpg





(3) Max Range - Basic CoCo + Twin-Lead TL for impedance matching - gives best results
CoCo-4-Element+42mmTL-RG6-114mm-18hrs run-03 Nov 2014.jpg







Layout - Basic CoCo + Twin-Lead TL for impedance matching - gives best result

DSC03420-R.jpg




Test Setup
DSC03395.jpg



Twin-Lead Length Calculations
DSC03417-R.jpg

 
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ab cd

Senior Member
The beauty of Twin-Lead SWR reduction method is that it requires only changing the length of Twin-Lead, while observing the max range & max number of aircraft picked by rtl1090/adsbScope/VRServer.

With push-pin construction in above sketch, Twin-Lead's length adjustment is easily achieved by pushing the feeder coax towards CoCo to reduce the length & pulling feeder coax away from CoCo to increase the length.

Another beauty of this arrangement is that even if the RG6 coax's exact VF is not known, and the CoCo is made with the element length 114 mm, the SWR can still be reduced to below 2, by adjusting the length of Twin-Lead between 30mm & 60mm.

For guidance, a table is given below which shows the optimum length of Twin-Lead for different VF (obtained by simulation).

Twin-Lead Table.PNG
 
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ab cd

Senior Member
If after making a coco, one find it is not working good, one can't fix it. He has to discard it, and start over by making a new one, which may again not work good. This is a normal situation in DIY coco.

If this happens with twin-lead compensated coco, one does not have to discard it. Performance can be made good by adjusting length of twin-lead.

The main beauty of twin-lead compensated coco is that it is adjustable by simply sliding the feeder coax a few mm towards or away from coco.

The drop in performance caused by inaccurate VF or not-so-good workmanship, is largely compensated by adjusting the twin-lead length, and one does not have to discard the coco.
 
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