LoRa/LoRaWAN tutorial 46: Collinear Antenna
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- เผยแพร่เมื่อ 19 พ.ค. 2024
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This is part 46 of the LoRa/LoRaWAN tutorial.
In this tutorial I will explain what a collinear antenna is and how to build one.
A collinear antenna is actually an array of dipole antennas stacked one above the other so that they are all in a straight line, i.e., "co linear."
On internet you can find several designs how to build a collinear antenna:
Collinear antenna 1
www.thethingsnetwork.org/foru...
Collinear antenna 2
github.com/IRNAS/ttn-irnas-gw/
I have build both antennas and will demonstrate how these antennas performs in this tutorial.
Please note: I have made some modifications to both designs.
Collinear antenna 1 4NEC2 card deck:
www.mobilefish.com/download/l...
A more accurate procedure how your antenna actually performs in the real world:
github.com/LoRaTracker/Antenn...
More information about the end node, see:
www.mobilefish.com/developer/...
The end node uses the MCCI LoRaWAN LMIC Library:
github.com/mcci-catena/arduin...
The end node uses the following sketch:
www.mobilefish.com/download/l...
Google map with gateway locations:
drive.google.com/open?id=18SK...
Collinear antenna 1 performance test A logged data:
www.mobilefish.com/download/l...
Collinear antenna 1 performance test A tilted logged data:
www.mobilefish.com/download/l...
Collinear antenna 1 performance test B logged data:
www.mobilefish.com/download/l...
Collinear antenna 1 conclusion
Based on the results of performance test A and B, I conclude that the collinear antenna 1 performance is quite similar to the ½λ dipole antenna.
If I ONLY look at elevation angles (α) between -1° and 3°.
This assumption is supported by comparing the 4NEC2 radiation pattern in the vertical plane between the ½λ dipole antenna and the collinear antenna 1 at elevation angles (α) between -1° and 3°.
Collinear antenna 2 4NEC2 card deck:
www.mobilefish.com/download/l...
Collinear antenna 2 performance test A logged data:
www.mobilefish.com/download/l...
Collinear antenna 2 performance test B logged data:
www.mobilefish.com/download/l...
Collinear antenna 2 conclusion
Based on the results of performance test A and B, I conclude that the collinear antenna 2 performance is much better compared to the ½λ dipole antenna.
More gateways in my area were able to receive the transmitted sensor data.
This is also collaborated looking at the 4NEC2 radiation pattern in the vertical plane and the fact that all my nearby gateways operates at an elevation angle (α) between -1° and 3°.
Collinear antenna 2 has a better antenna performance compared to collinear antenna 1.
More gateways were able to receive the transmitted sensor data using collinear antenna 2 compared to collinear antenna 1.
Collinear antenna 2 has a higher gain at elevation angles between -1° and 3° compared to collinear antenna 1, according to the 4NEC2 radiation patterns in the vertical plane.
The 4NEC2 program simulates how the antenna behaves but MY collinear antennas are not accurately modelled.
Which means that the generated radiation patterns and other antenna parameters are just a rough indication of how the real collinear antennas behaves.
If you want accurate radiation patterns and other antenna parameters, these antenna measurements should be performed in an anechoic chamber.
If a collinear antenna is put inside a plastic / glass fiber tube, always measure the antenna parameters with an antenna analyser when the antenna is inside the tube.
It is possible to put the collinear antenna inside a PVC tube, but use a thin tube wall.
Gray PVC tubes may contain carbon.
Carbon absorbs or reflect RF signals.
To check if the PVC tube contains carbon, you can apply the "microwave" method.
The microwave method is explained at:
www.thethingsnetwork.org/foru...
WARNING: IF YOU APPLY THE MICROWAVE METHOD, IT MAY DESTROY YOUR MICROWAVE. DO THIS AT YOUR OWN RISK!
Check out all my other LoRa/LoRaWAN tutorial videos:
• LoRa/LoRaWAN tutorials
Subscribe to my TH-cam channel:
/ @mobilefish
The presentation used in this video tutorial can be found at:
www.mobilefish.com/developer/...
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This content probably won't become a viral video but as an electrical engineer and amateur radio operator, I was very interested and enjoyed the entire hour. Thank you. I appreciated the attention to detail when performing the real world tests, and the NEC modeling and how well that conformed to the demonstrated performance. You are the only person I've heard pronounce VSWR as "fizwahr". 🙂
thanks for sharing. looks like #2 is definitely a winner since #1 mostly radiates into the sky.
Thanks for your effort, this is one of greatest describing video about antennas I ve seen so far
Thank-you for this, I'm just an amateur radio ham, not a student but found this interesting, useful and easy to follow.
Just amazing explanation .. well done
Excellent explanation, thank you very much
super video, i get 1.29 swr with my build of your variant of the antenna nr 2. i tried a coaxial collinear antenna build but much harder than this and not near as good results, thank you so much!
I got a 1.7 swr, wondering how I bring that down...
What a great tutorial! Thak you so much!!
Excellent video, thank you.
Nice explanation thanks 💞
very informative!
very well done
Copper coated welding rods also make excellent radials. Steel inside with copper coat.
Is there a reason why you went with 1.8 mm copper wire? I'm in the US and closest one that I can find is 12AWG wire which is 2.053mm. 13AWG is 1.828mm and 14AWG is 1.628mm. 13AWG is very hard to find. Is it possible to use 2.053mm solid copper wire? Will that change the diameter of the loop? Can I still make the outer diameter of the loop to be 18.8mm? Thank you!
Thanks a lot!
tbh when i saw the loop fixed at 20mm while the antenna parts were in wavelength, i felt something was off about this design
Hi, great video!
I have a Q. Do you have info about the design of the loop ? Why this two different diameters (15 vs 29 mm)? Are loops geometry related to overall antenna dimensions? thanks
www.mobilefish.com/download/lora/lora_part46.pdf
(page 13) I started with a loop diameter of 15 mm and no radials but after measuring the antenna parameters this design is NOT good.
I have been tweaking the design and ended up with a final design (page 29), it has a loop diameter of 18.8 mm and radials.
The calculations of the lengths are a bit odd. Normally a colinear antenna constist of 1/4 wave to start, then 1/2 delay element, 1/2 radiating element, 1/2 wave delay element, 1/2 wave radiating element and then 1/4 wave element to close off the antenna. Thats a 2 element colinear antenna. In your design the 1/2 wave delay elements are exchanged for a coil which saves space. Which is nice!
But the 1/4 begin and 1/4 end and in between everytime a pair of 1/2 wave delay + 1/2 wave radiating elements are essential.
The electrical length of the delay+radiating element can be choosen depending on the radiation pattern is desired but should be a multiple of 1/4 wave. Like 1/4 or 2/4 wave or 3/4 wave.
The radiating element B in your video is 220mm long which is an odd length. For 868 MHz it could be 1/4 wave (*VF=0,96)= 82mm, or 1/2 wave (*VF) = 165mm, or 3/4 wave (*VF) = 248mm. And the beginning and end element should be 1/4 wave (*VF) = 82 mm. That should make the antenna more perfect in terms of elements length. Then the induction of the coils im not sure I never used coils in antenna's yet. But if those lengths for the elements are choosen atleast then the lengths of the elements are choosen correct, then modify the coils for best swr is what I would do. Or if the coils are unknown what to do with them, then for best colinear antenna the design is 1/4 wave then number of [ 1/2 wave delay element + 1/2 wave radiating elements] and then 1/4 wave element to close the antenna off. (can make a metal wip on the end to outside of pvc tube then after the antenna is contruction parts of the whip can be trimmed for best swr.
Its worth trying maybe you can get an enhanced colinear antenna out of it!
Also, great job at your tutorial video's I enjoy watching it, its very informational but also fun to watch!
Formula for the loop size if want to use on other freq?
How you calculate diameter of the rings according to frequency ?
Please calculate an antenna in 435 Mhz.
I have made 5 so far and they all work perfectly for mining NHT in 868 Mhz coins.
Great tutorial! Thak you.
Hi Liviu, sorry I do not have the time to create an antenna design for 435 Mhz. Have you watched LoRa/LoRaWAN tutorial 38: NEC Antenna Modelling Software, 4NEC2? With this knowledge and the 4NEC2 card deck (explained in tutorial 46) www.mobilefish.com/download/lora/collinear2_868mhz_4nec2.nec.txt you can modify the antenna design yourself.
It would definitely help if you have a N1201SA Vector Impedance Analyser (tutorial 40).
Hello,
Please when you can calculate my antenna and send it to galiviu@yahoo.com.
If I have the scheme and dimensions I have an antenna analyzer for measurements.
Thank you for the answer. YO3FYO- Liviu
@@liviugabreanu-yo3fyo354 I'm sure there is plenty of relevant info on the web to help YOU design and test such an aerial. You have the means to test it which is more than most people have.
how did you come to deter the size of the phasing loop size normally it got to be a 1/2 wave length to cancel out the radiating field yours is not even 1/4 wave im sure there is method in your madness
Hi,
I am wondering could it be used in VHF amateur radio?? And how would the diameter of space Computex, Thank you.
Can calculate one in 435 mhz ??
As i see this is max gain 5.22db on 11meters above ground ,so what if i am on on some 3 meters above ground? How can i make some 10-12db antena to make better cover of signal??Big regards, great video!
I took the LORA device near the antenna to use a very short 50 ohm 1 -2 meter cable.
It would be one of the methods.
Hi.....I am wondering if this antenna can be used in 144 MHz???
I am still confusing in the measurement of loop.
Thanks.
No. This particular antenna design & dimensions is for 868 MHz.
No, this is specifically for 868MHz, but could probably be scaled for 144MHz and tuned with some fiddling and experimentation. However, there are loads of designs for 2 metre aerials of all sorts around on the web if you do a search.
Hello, I learned so much with your tutorials. I created a own antena desing and send by e-mail to you. I would like to share with you and if possible, I would like a quick review from you. Thanks in advane.
I didn't see the velocity factor considered in your calculations!
Hi, I build this antenna version 2 twice and every time the best frequency was about 850Mhz. I could tune it a little bit but best frequency was never higher than 859MHz. So what can I do now or what did I wrong?
It is difficult to say what causes this. You can use the 4NEC2 antenna model and play with the parameters: www.mobilefish.com/download/lora/collinear2_868mhz_4nec2.nec.txt
I have noticed that the spacing S, see: www.mobilefish.com/download/lora/lora_part46.pdf is quite sensitive.
@@Mobilefish Thanks a lot for your answer 😊
At these frequencies, there is a lot of inductive and capacitive reactance created by using those wire connectors. Look how close the connector gets to the shield side of the chassis mount connector; that's NOT good. Similarly at the phasing coils.
Measure twice, cut once, test thrice squared.
How to get more swr? I nerd 1.5 to 2.5, thank you
I got 1.8 was wondering how to get it down to 1.5/1.2
Hmm - too little physics in here - the details dont matter much 0,5 mm ? - on the other hand you are testing long range antennas in a closed room in a distance of 6 meters...