ADS-B DIY Antenna

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jepolch

Active Member
[B
ALL collinears are very difficult for DIY. Reason: being multi element, require phasing elements between vertical receiving elements.

The phasing elements are extremely sensetive to dimensions. An error of few mm in DESIGN, or CONSTRUTION can push a collinear from excellent to poor category. The phasing element are coils (coiled whip), stubs (franklin), core wire of coax (coco).

The collinears are best when they are designed by Computer Aided Design software, followed by production using templates and precision metal forming macinary, followed by testing/trimming/adjustment with test equipment & anechoic chamber.

It seems the designer of your collinear has paid no attention to phasing coil's accuracy. The design does not include height of the coil, a very important dimension fir correct phasing.
GRRRR! :mad: ;)
 

ab cd

Senior Member
I just checked the website from where you got this coiled whip design. I can see in the diagram the height of coils is 10mm, but dia of coils is not shown in the diagram. Text is in french? ,I did not understand. Does it give dia of coil?

The phasing depends on dia of coil, number of turns, height of coil, and dia of wire.

Even if dimensions are given, what is the gaurantee it has been worked out by a reliable antenna modelling software?

antenne_1090_fouet-200x300.jpg . ADS-B-antenna-drawing.gif
 
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jepolch

Active Member
I just checked the website from where you got this coiled whip design. I can see in the diagram the height of coils is 10mm, but dia of coils is not shown in the diagram. Text is in french? ,I did not understand. Does it give dia of coil?

The phasing depends on dia of coil, number of turns, height of coil, and dia of wire.

Even if dimensions are given, what is the gaurantee it has been worked out by a reliable antenna modelling software?

View attachment 1056 . View attachment 1057
Actually, the gap between turns is 4 mm and the diameter of the coil is 10 mm. I probably didn't observe those directions very literally, and I made the length of the coil 69 mm (so my diameter was more like 12 mm) as I thought that's what it should be if it's 1/4 wave. Well, can you point me to a better design for this kind of colinear? I'd like to make one that works. I have lots of wire and much free time. :)
 

ab cd

Senior Member
Actually, the gap between turns is 4 mm and the diameter of the coil is 10 mm. I probably didn't observe those directions very literally, and I made the length of the coil 69 mm (so my diameter was more like 12 mm) as I thought that's what it should be if it's 1/4 wave. Well, can you point me to a better design for this kind of colinear? I'd like to make one that works. I have lots of wire and much free time. :)
I have simulated and built several designs of coiled whip & coiled dipoles. ALL FAILED. Reason: the antenna simulation software was not accurate enough, and I dont have machinary to make it accurately, and dont have any test equipment (except analog multimeter) to test & trim/tune.
:mad:
 

jepolch

Active Member
I'm just very glad I have at least one good antenna. It performs great and it's the standard I measure all other antennas against. The cantenna comes closest to this antenna.
 

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ab cd

Senior Member
I'm just very glad I have at least one good antenna. It performs great and it's the standard I measure all other antennas against. The cantenna comes closest to this antenna.
The easiest antennas which are simple, have dimensional tolerance, do not require very accurate & difficult shape, and have perfect swr(1)/impedance(75ohm), are the ones whose upper limb is ¼ wavelength whip. The down limb can be another ¼ wavelength limb (½ wavelength dipole), a ground plane disk, groundplane horizontal radials, groundplane slanting radials (spider), or a combination of groundplane disk+¼ wave cylindrical down limb (cantenna).

All these ¼ wavelength whipped antennas have advantage of swr=1, impedance=75ohms, but disadvantage of low gain (1.5 to 2 dBi). The low gain can easily be compensated by an amplifier. Hence these antennas+amplifier make the most practical and easy solution for most DIY enthusiasts.

Once the DIY enthusiast has put his system in successful operation using these simpleton antenna+amplifier, he can try his luck with collinears. Some lucky ones do hit a gold mine or jackpot.
 
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Sjacket99

Member
Here is a couple pictures of my little server room that we built. We closed it in to make a room. I have a 12x12 inch filter grill on the bottom of the door. There is two 120 mm fans (120Volt) that is on a thermostat, so when it gets warm the 2 fans will turn on. Plus I finished my temp sensor using a Raspberry Pi. I also hooked up a LCD screen to show the temp of the room. Plus it has a web GUI to view the temp from a internet device. The LCD will show the temp and hight and low temp also. I just need to finish mounting the Pi and screen to a plate I have and mount it in the rack. Pictures to come soon.
 

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ab cd

Senior Member
Here is a couple pictures of my little server room that we built. We closed it in to make a room. I have a 12x12 inch filter grill on the bottom of the door. There is two 120 mm fans (120Volt) that is on a thermostat, so when it gets warm the 2 fans will turn on. Plus I finished my temp sensor using a Raspberry Pi. I also hooked up a LCD screen to show the temp of the room. Plus it has a web GUI to view the temp from a internet device. The LCD will show the temp and hight and low temp also. I just need to finish mounting the Pi and screen to a plate I have and mount it in the rack. Pictures to come soon.
Wow, GREAT!
Room # 127.0.0.1 :)
 

jepolch

Active Member
The easiest antennas which are simple, have dimensional tolerance, do not require very accurate & difficult shape, and have perfect swr(1)/impedance(75ohm), are the ones whose upper limb is ¼ wavelength whip. The down limb can be another ¼ wavelength limb (½ wavelength dipole), a ground plane disk, groundplane horizontal radials, groundplane slanting radials (spider), or a combination of groundplane disk+¼ wave cylindrical down limb (cantenna).

All these ¼ wavelength whipped antennas have advantage of swr=1, impedance=75ohms, but disadvantage of low gain (1.5 to 2 dBi). The low gain can easily be compensated by an amplifier. Hence these antennas+amplifier make the most practical and easy solution for most DIY enthusiasts.

Once the DIY enthusiast has put his system in successful operation using these simpleton antenna+amplifier, he can try his luck with collinears. Some lucky ones do hit a gold mine or jackpot.
Thanks for the excellent explanation. You summed up just about all the wisdom of your writings in this thread into one post (minus the illustrations :)).
 

jepolch

Active Member
Here is a couple pictures of my little server room that we built. We closed it in to make a room. I have a 12x12 inch filter grill on the bottom of the door. There is two 120 mm fans (120Volt) that is on a thermostat, so when it gets warm the 2 fans will turn on. Plus I finished my temp sensor using a Raspberry Pi. I also hooked up a LCD screen to show the temp of the room. Plus it has a web GUI to view the temp from a internet device. The LCD will show the temp and hight and low temp also. I just need to finish mounting the Pi and screen to a plate I have and mount it in the rack. Pictures to come soon.
Very nice job! Welcome back. :)
 

jepolch

Active Member
The easiest antennas which are simple, have dimensional tolerance, do not require very accurate & difficult shape, and have perfect swr(1)/impedance(75ohm), are the ones whose upper limb is ¼ wavelength whip. The down limb can be another ¼ wavelength limb (½ wavelength dipole), a ground plane disk, groundplane horizontal radials, groundplane slanting radials (spider), or a combination of groundplane disk+¼ wave cylindrical down limb (cantenna).

All these ¼ wavelength whipped antennas have advantage of swr=1, impedance=75ohms, but disadvantage of low gain (1.5 to 2 dBi). The low gain can easily be compensated by an amplifier. Hence these antennas+amplifier make the most practical and easy solution for most DIY enthusiasts.

Once the DIY enthusiast has put his system in successful operation using these simpleton antenna+amplifier, he can try his luck with collinears. Some lucky ones do hit a gold mine or jackpot.
I really like the cantenna, in principle. It's easy to make and works great. The only problem I have with it is that the top of the antenna (bottom of can) is concave and acts as a well to hold water. I don't know, but it seems like it will affect the operation of the antenna. Put it in an enclosure and you have the problem of condensation outside and inside the enclosure. The conetenna seems like a good compromise as water can't sit on the surface. I don't think I have gotten it perfected yet, though.
 

Sjacket99

Member
I really like the cantenna, in principle. It's easy to make and works great. The only problem I have with it is that the top of the antenna (bottom of can) is concave and acts as a well to hold water. I don't know, but it seems like it will affect the operation of the antenna. Put it in an enclosure and you have the problem of condensation outside and inside the enclosure. The conetenna seems like a good compromise as water can't sit on the surface. I don't think I have gotten it perfected yet, though.

What if you drill like 1/16 or 1/8 inch hole in the can to let the water drain out.
 

jepolch

Active Member
What if you drill like 1/16 or 1/8 inch hole in the can to let the water drain out.
I considered that. It's a little difficult to waterproof the coax connection up inside the can. Nice thing about the cantenna is that it's a sealed dome over the coax connection, so you don't have to waterproof it. Drill the hole and you have water running over your coax connector.
 

ab cd

Senior Member
I really like the cantenna, in principle. It's easy to make and works great. The only problem I have with it is that the top of the antenna (bottom of can) is concave and acts as a well to hold water. I don't know, but it seems like it will affect the operation of the antenna. Put it in an enclosure and you have the problem of condensation outside and inside the enclosure. The conetenna seems like a good compromise as water can't sit on the surface. I don't think I have gotten it perfected yet, though.
I tried can of swiss sausage. It's bottom is flat with no rim, but it's length is too short.

I am considering to pour water on the bottom of cantenna, then put it in freezer for couple of hours, then with water at top frozen to ice, hook the cantenna to my antenna testing platform, and see how it performs.

My logical guess is that cantenna with water or ice in concave bottom wont affect performance.

Alternatively why not use beans can with flat bottom like giacomo1989 has done?

Cantenna - Beans can.jpg . Cantenna.JPG.jpeg
 
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Turorit

New Member
I've mounted my cantenna inside a piece of 90mm stormwater pipe with 2 endcaps. Seems to work ok :)
Coax feeds through the bottom, silicone around the hole.
 

trigger

Member
@jepolch I'm just very glad I have at least one good antenna. It performs great and it's the standard I measure all other antennas against. The cantenna comes closest to this antenna.

There are lots of antenna designs that work at 1090 MHz as we have found. We are comparing different antennas to find the "best" which is why we've rejected so many designs.

As ab cd says the collinears are difficult. I seem to have made one which works well. I've made dozens that didn't. :rolleyes:

All good fun and a great learning experience.
 
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