I know this is an old video but I'm just getting into antenna building and I went by these measurements and built my own antenna just like this for the R9. All I have at the moment to test with is the ImmersionRC power meter. I put the original antenna on the R9 module, with the RC on one table, transmitter set on 10mw.. put the meter on another table which is about 6 feet from the RC.. and I put the super 8 antenna on the meter and got a reference reading.. then put my 1st DYS antenna on the meter, which is built to these measurements, and it matched the power reading from the super 8 exactly!! So I will vouch on Pawels measurements. Good job!! I have the same VSWR meter on the way. Thanks for your time helping the little guys!!
It'll match the power, but it's the frequency that will differ in cases where the length is off. I think they are are tolerant to a degree and you may only lose a little bit of range if not absolutely _perfect_ . I've DIY'd a few antennas that weren't absolutely spec, and they seemed to work fine even out to distance.
I made one last night as I'm all about NOT paying $9 per antenna for my 20 quads (I had 10, 2.4 ghz monopoles), looked perfect, but when I checked for continuity between the active element/ipex and the ground/ipex I only had connectivity between the ground and ipex. I cleaned my magnet wire like a champ. This could have only been due to faulty instructions lol.
Sorry, one more question: could you please test the TBS Diamond antenna on your testing device? If you don't own one, I could send you one. Thanks again and best regards.
Hi Pawel,....How important is the 110mm base length? and is this also okay for the R9MM receiver...?...My FrSky antenna has a base length of only 80mm..? FrSky have different base lengths for their different receivers it would seem....even though they operate on the same (2.4G) frequency.
In theory, length of the feedline depends on frequency and velocity factor of the coax. Length should be a multiple of half wavelength in the coax. Here we assume that velocity factror is around 0.65. This is just a safe assumption and antenna would still work with 10cm or 13cm and so on
Hi Pawel, thanks for your answer, Using my 868mhz True-Mox and 200mw fixed, My RSSI is hopeless at around 40% only 1km out....even after i extended my std antenna as in your video. The R9MM receiver seems to give random results in terms of range...?
Hi, Teo questions, can I re-use my existing r9mm antenna and extent both parts of the dipole to 80mm for 868? The problem is that even doing that the feed line is too short and would be 8cm approx instead of the 11 you say. Second question is why you say 8cm for 868 while in the other video for the tx dipole you say 77mm for 868.
Hello Pawel, I was wondering how would one make an antenna that is smaller for micros 3 in and under kwads. I seen TBS has one for their rx but how would one go about making one for an r9 mini or mm? Thanks for your great content.
Any antenna is the same length as prescribed by the formula. The difference lies in how much of that antenna is a coil hidden by the plastic of a commercial one. These small dipoles have a coil that corresponds to the actual length, but the coil part is hidden in the centre plastic. Old analog car cellphone antennas had a coil in the middle of them. Not for aesthetics but just to make up the length without having to make a longer, floppy antenna.
Very informative video. I plan to build a micro quad and I wonder if it is possible to make a short crossfire antenna, half length of the regular antenna...
Thanks, I've made the same antennas..and they were working just fine. But after some more crashes, I've fixed the antennas on my both quads, just like I did before. But now I get some bad intereference on my video feed, on both quads. When I hold the antenna with my hand the lines dissapear, and of course when I turn off the radio they are gone too. What could be the problem, I think the range is not affected, just some lines in my video
Dear Pawel, is it possible to make a longer Pigtail as 11 cm and mount the passive-End tightend to the Pigtail, that you have an long "I" instead of an "T"? Or does it makes a difference for the reception? Causo with a strong enough "I" which is flexible, it would be easier to mount on my Quad. And you say its not the best but its a good antenna. How can i tune it to a better Antenna? What makes the difference? Is a use of 99,9% copper wire the best for reception?
Hi Pawel. Thank you very much for the video. 2 questions: how dependent are the 2 elements of the antenna on one another? What is the effect of bending the ground element 90 or to an L shape from the solder joint point on the SWR? 2nd question: Can you make the ground element start from a different part of the pigtail to the live element? Let's say I'd like to put the ground element on the back of the quad horizontally and the live from the top plate of the quad vertically. Thank you again!
Hi, so does that center piece have to lean to one side with heatshrink or can you epoxi it as an actual T and put some sguru stuff around it or a 3d printed part?
Can you confirm if I set it at 90 degress does the antenna remains with the same efficency and the loss is due to geometry between RX and the TX ? Thank you
Paweł Spychalski so i damaged a r9mm antenna can i use spare sma pigtails to make my 2.95" ends? just use the whole pigtail as my solid ground and signal? as long as the ipex 4 is seperated signal and ground? i dont have copper welding wire is why i ask..
Hi Pawel, thanks for the video. What do you think straight dipole performance compare to V-dipole? If V is better how I calc the length of each arm? Thanks in advance!
If I would use flexible coaxial core (the inner part of the RG178 cable or something similar) instead of "simple welding copper wire with shrinkwrap cover" what would be the size to cut?
I measured my TX and RX Immortal T-Antennas and both tips of them seem to be connected to ground/shielding? The inner feedline has no conact to both left & right ends, how does this work? Is it a different antenna type?
Just wondered how bad is the reception to use a 915MHz antennas on a radio that transmit 868MHz and a 915MHz on the model as well? I just wondered because i ordered the wrong ones...
AWESOME video, super helpful! Can I use 1.1cm instead of 11cm? I wanna make a super short one... Even better, can I solder directly to the SMA connector?
Siema kolego mam pewny pomysl i nie wiem jesli mozna uzyc do tx anteny te same rozmiary lub inne, tez nie wiem jezeli sma pigtail zamiast ipex pigtaila moze byc jakiego kolwiek rozmiaru? Cale to cos bedzie dla qx7 ze integrowana antena dla elrs do 868 mhz w madle tylnym ktore bedzie zamiast metalove z plastiku pewnie 3D druk. Dzieki za odpowiedz przodem
In vacuum? Yes. But antenna is not made from vacuum, so after adding velocity factor it's closer to 73mm. But it all depends on the antenna itself and material
Paweł I don’t have a 0.8mm copper welding wire but do have an electrical wire that contains a few cores however each of them has the copper core 1.33mm thick - would it be an issue? Or I should really find something exactly 0.8mm ? Thanks
dude i ii broke the freckn antenna of r9 mini and i bought some ipex 4 andb they dont matchhhh.. theyr not for r9 mini... so keep looking and found a guy here in mexico that sells antennas buttt they are LBT.... can i put them in the fcc r9 mini... or i have strictly having the fcc antenna what can happen if u buy that lbt what u recomend me .... i bought 5 antenas from horus rc.. buttt the havnt arrived about a month,,,,,,,those are 900mhz
Hello Pawel so far so good, but we all know the vertical mounting should be preferable... In most cases on mini quads the vertical mounting is not that easy with a quarter wavelength... So what do you think about eighth wavelength for 868/915 MHz?
I have an honest question regarding your comment......does it really matter if your TX antenna is aligned the same as the RX? (as in horizontal as opposed to vertical) If they match, do you really need a vertical antenna? I'm presently building a LR 7", and want to use an R9 slim+ flashed with ELRS and diversity antennas so I was thinking to put one in the tail horizontal, and one in front more aligned vertical to cover all the bases.
Where the "welding wire" comes from? By the spool and by the bends in the wire it looks like a soft pure copper wire. Welding wire should be (hard) steel coated with copper and come on easy to unspool roll.
One question Pawel :) Since you look like you might know :) When I was playing with 4nec2 program - basic "whip" antenna had a very similiar radiation patter to dipole. In this case do you think that the way we mount this antenna matters? Because if we wont mount it as a horizontal "T" then it is basically a whip antenna with an extra element. So could the way we mount the antenna change its performance? Not mentioning the "V" antenna :D which is practicaly any "T" antenna after a crash :D
You both forgot to take into account the velocity factor of the copper and heatshrink around it. The velocity factor of copper wire is around .95 and the heatshrink is likely similar making the ideal length around 78mm.
What exactly is 0.8mm "welding wire", never heard of "welding wire" except for use in a tig welder or something like that Edit: can I use solid core 12 or 14 gauge electrical wire? 2nd edit: looks like 28 gauge wire is close to the right size. Not 12 or 14
@@FPVUniversity Thanks, so i guess 0.3 is possible for wrapping them outside of my whoop airducts. The original dipole from frsky looks really thin also but there's no way for me to measure it lol xD
Cool stuff guy. I'm an old, retired engineer who couldn't explain what you just displayed so well. Cudos. "Live long and prosper." Thanks Spock.
I know this is an old video but I'm just getting into antenna building and I went by these measurements and built my own antenna just like this for the R9. All I have at the moment to test with is the ImmersionRC power meter. I put the original antenna on the R9 module, with the RC on one table, transmitter set on 10mw.. put the meter on another table which is about 6 feet from the RC.. and I put the super 8 antenna on the meter and got a reference reading.. then put my 1st DYS antenna on the meter, which is built to these measurements, and it matched the power reading from the super 8 exactly!! So I will vouch on Pawels measurements. Good job!! I have the same VSWR meter on the way. Thanks for your time helping the little guys!!
It'll match the power, but it's the frequency that will differ in cases where the length is off. I think they are are tolerant to a degree and you may only lose a little bit of range if not absolutely _perfect_ . I've DIY'd a few antennas that weren't absolutely spec, and they seemed to work fine even out to distance.
Just a little tip, if you stretch the cobber wire a little, it will get harder (deformation hardening) and straight.
I made one last night as I'm all about NOT paying $9 per antenna for my 20 quads (I had 10, 2.4 ghz monopoles), looked perfect, but when I checked for continuity between the active element/ipex and the ground/ipex I only had connectivity between the ground and ipex. I cleaned my magnet wire like a champ. This could have only been due to faulty instructions lol.
Sorry, one more question: could you please test the TBS Diamond antenna on your testing device? If you don't own one, I could send you one. Thanks again and best regards.
I can do it. I have a swr 1201
yep. better diy than wait for 2 -3 weeks and be dissapointed. nicely done.
Nice tip, could I half all the values for a compact antenna? Not expecting to keep the range but to add crsf to micro quads and stick to one protocol.
Hi Pawel,....How important is the 110mm base length? and is this also okay for the R9MM receiver...?...My FrSky antenna has a base length of only 80mm..?
FrSky have different base lengths for their different receivers it would seem....even though they operate on the same (2.4G) frequency.
In theory, length of the feedline depends on frequency and velocity factor of the coax. Length should be a multiple of half wavelength in the coax. Here we assume that velocity factror is around 0.65. This is just a safe assumption and antenna would still work with 10cm or 13cm and so on
Hi Pawel, thanks for your answer, Using my 868mhz True-Mox and 200mw fixed, My RSSI is hopeless at around 40% only 1km out....even after i extended my std antenna as in your video.
The R9MM receiver seems to give random results in terms of range...?
either you have damaged hardware or you do something very very wrong. wht's the altitude in your case?
Try to bind again
I've seen two of your videos on antenna length and one gives 77mm for 866mhz and this one gives 80mm for 866mhz.
Which one should I go for?
Thanks!
Very good. Was thinking the two parts need to be 90° from each other, no?
Hi, Teo questions, can I re-use my existing r9mm antenna and extent both parts of the dipole to 80mm for 868? The problem is that even doing that the feed line is too short and would be 8cm approx instead of the 11 you say.
Second question is why you say 8cm for 868 while in the other video for the tx dipole you say 77mm for 868.
It's so much helpful for me. I'm planning to extend the feed line. Do i have to use 220mm for feedline? 110mm is not enough for me.
Hello Pawel, I was wondering how would one make an antenna that is smaller for micros 3 in and under kwads. I seen TBS has one for their rx but how would one go about making one for an r9 mini or mm?
Thanks for your great
content.
Any antenna is the same length as prescribed by the formula. The difference lies in how much of that antenna is a coil hidden by the plastic of a commercial one. These small dipoles have a coil that corresponds to the actual length, but the coil part is hidden in the centre plastic. Old analog car cellphone antennas had a coil in the middle of them. Not for aesthetics but just to make up the length without having to make a longer, floppy antenna.
Hai. I want to try to make antena 915.
The question is that coaxial cable must be 110mm?
If I make shorter for example 60-80mm?
Thank for the answer
Very informative video.
I plan to build a micro quad and I wonder if it is possible to make a short crossfire antenna, half length of the regular antenna...
Thanks, I've made the same antennas..and they were working just fine. But after some more crashes, I've fixed the antennas on my both quads, just like I did before. But now I get some bad intereference on my video feed, on both quads. When I hold the antenna with my hand the lines dissapear, and of course when I turn off the radio they are gone too. What could be the problem, I think the range is not affected, just some lines in my video
Dear Pawel, is it possible to make a longer Pigtail as 11 cm and mount the passive-End tightend to the Pigtail, that you have an long "I" instead of an "T"? Or does it makes a difference for the reception? Causo with a strong enough "I" which is flexible, it would be easier to mount on my Quad.
And you say its not the best but its a good antenna. How can i tune it to a better Antenna? What makes the difference?
Is a use of 99,9% copper wire the best for reception?
Hi Pawel. Thank you very much for the video. 2 questions: how dependent are the 2 elements of the antenna on one another? What is the effect of bending the ground element 90 or to an L shape from the solder joint point on the SWR? 2nd question: Can you make the ground element start from a different part of the pigtail to the live element? Let's say I'd like to put the ground element on the back of the quad horizontally and the live from the top plate of the quad vertically. Thank you again!
Great question.. too bad it never got answered 😞
Hi, so does that center piece have to lean to one side with heatshrink or can you epoxi it as an actual T and put some sguru stuff around it or a 3d printed part?
Can you confirm if I set it at 90 degress does the antenna remains with the same efficency and the loss is due to geometry between RX and the TX ?
Thank you
Paweł Spychalski so i damaged a r9mm antenna can i use spare sma pigtails to make my 2.95" ends? just use the whole pigtail as my solid ground and signal? as long as the ipex 4 is seperated signal and ground? i dont have copper welding wire is why i ask..
Hi Pawel, thanks for the video. What do you think straight dipole performance compare to V-dipole? If V is better how I calc the length of each arm? Thanks in advance!
If I would use flexible coaxial core (the inner part of the RG178 cable or something similar) instead of "simple welding copper wire with shrinkwrap cover" what would be the size to cut?
I measured my TX and RX Immortal T-Antennas and both tips of them seem to be connected to ground/shielding? The inner feedline has no conact to both left & right ends, how does this work? Is it a different antenna type?
Just wondered how bad is the reception to use a 915MHz antennas on a radio that transmit 868MHz and a 915MHz on the model as well?
I just wondered because i ordered the wrong ones...
AWESOME video, super helpful!
Can I use 1.1cm instead of 11cm? I wanna make a super short one... Even better, can I solder directly to the SMA connector?
Hey. good video and useful. Where did you buy sma-ipex4 for swr metr?
Hi Pawel, Great video. Does anyone know where to get a meter like the one in the video that works at 5.8ghz?
They all seem to max out at 2.7.
Siema kolego mam pewny pomysl i nie wiem jesli mozna uzyc do tx anteny te same rozmiary lub inne, tez nie wiem jezeli sma pigtail zamiast ipex pigtaila moze byc jakiego kolwiek rozmiaru? Cale to cos bedzie dla qx7 ze integrowana antena dla elrs do 868 mhz w madle tylnym ktore bedzie zamiast metalove z plastiku pewnie 3D druk. Dzieki za odpowiedz przodem
Ale co? Napisz to jeszcze raz, zdanie po zdaniu tak aby nie tylko autor zrozumiał o co chodzi
@@FPVUniversity jestem z czech to troche za trudno dla mnie znów przypominać sobie polszczyzny ze szkoły podstawowej ale w domu spróbuje znowu
try in English maybe
Veryn nice dude. But you cant put your finger on antenna when you mesure the swr?
What does the feed length matter?
Can I use silicone glue in place of epoxy?
Great video! 👍 Just a stupid question i guess, buuut the same anenna-rules goes for the Transmitter-side too right?
Merry Christmas!
yes, the same rules
What is the best kind of wire to do this?
Pretty nice work, dude! Fantastic! 😃
Merry Christmas and a happy new year! 😊
ho ho ho and stuff ;)
for 915 Mhz should the quarter waver antenna length be 82 mm ? since the full wavelength is 328mm
In vacuum? Yes. But antenna is not made from vacuum, so after adding velocity factor it's closer to 73mm. But it all depends on the antenna itself and material
@@FPVUniversity oh yes forgot about that, thanks for the clarification
Paweł I don’t have a 0.8mm copper welding wire but do have an electrical wire that contains a few cores however each of them has the copper core 1.33mm thick - would it be an issue? Or I should really find something exactly 0.8mm ? Thanks
that should work as well. But overall tune might be slifghtly different
dude i ii broke the freckn antenna of r9 mini and i bought some ipex 4 andb they dont matchhhh.. theyr not for r9 mini... so keep looking and found a guy here in mexico that sells antennas buttt they are LBT.... can i put them in the fcc r9 mini... or i have strictly having the fcc antenna what can happen if u buy that lbt what u recomend me .... i bought 5 antenas from horus rc.. buttt the havnt arrived about a month,,,,,,,those are 900mhz
Hi ! Happy new year 2019 !
Could you test Diamond immortal and classic TBS antenna ?
Hello Pawel so far so good, but we all know the vertical mounting should be preferable... In most cases on mini quads the vertical mounting is not that easy with a quarter wavelength...
So what do you think about eighth wavelength for 868/915 MHz?
I have an honest question regarding your comment......does it really matter if your TX antenna is aligned the same as the RX? (as in horizontal as opposed to vertical) If they match, do you really need a vertical antenna?
I'm presently building a LR 7", and want to use an R9 slim+ flashed with ELRS and diversity antennas so I was thinking to put one in the tail horizontal, and one in front more aligned vertical to cover all the bases.
Where the "welding wire" comes from? By the spool and by the bends in the wire it looks like a soft pure copper wire.
Welding wire should be (hard) steel coated with copper and come on easy to unspool roll.
One question Pawel :) Since you look like you might know :) When I was playing with 4nec2 program - basic "whip" antenna had a very similiar radiation patter to dipole. In this case do you think that the way we mount this antenna matters? Because if we wont mount it as a horizontal "T" then it is basically a whip antenna with an extra element. So could the way we mount the antenna change its performance? Not mentioning the "V" antenna :D which is practicaly any "T" antenna after a crash :D
BTW FINALLYYYY! Thx for the DIY :) trying it out right away
Whips, as monopoles need good "ground plane". This is why dipoles are used - they provide ground plance . And antennas always vertical
Well that will work for me dude!
Cheers
do you still use the same device to measure antennas?
yes
Ottimo lavoro
Thanks very much Pawel
Happy Christmas
Can I make a antenna of 0.8mm copper wire because I have that?
yes, 0.8mm is perfect
@@FPVUniversity the thickness of the copper doesnt really matter at all right?
@@arendmookhoek4314 don't go too thin, we need the skin effect
@@FPVUniversitywould that matter if it is enameled coated?
For 868MHz you need exact 8,84cm (1/4 Lambda). 8cm is way too imprecisely for long range distances.
I guess he really wanted it tuned to 937 mHz at 8cm. 868 is actually 8.64cm
You both forgot to take into account the velocity factor of the copper and heatshrink around it. The velocity factor of copper wire is around .95 and the heatshrink is likely similar making the ideal length around 78mm.
Hi Pawel, is this work with 2.4 (for longer range) ?.
no, this is 868/915
@@FPVUniversity, thanks for the reply. 👍
What exactly is 0.8mm "welding wire", never heard of "welding wire" except for use in a tig welder or something like that
Edit: can I use solid core 12 or 14 gauge electrical wire?
2nd edit: looks like 28 gauge wire is close to the right size. Not 12 or 14
Please estimate what max distance could be reached with it nice antenna?
any distance, if you put any high power through it. how far can man throw a stone? depends on the power of the thrower, right?
range depends on dozens of reasons and antenna is only one of them.
This is really helpful! Thank you so much.
Is the gauge wire important?
not that much. Circa 1mm is diameter is fine
@@FPVUniversity Thanks, so i guess 0.3 is possible for wrapping them outside of my whoop airducts. The original dipole from frsky looks really thin also but there's no way for me to measure it lol xD
Will 1mm copper wire be ok???
yes
Awesome information!
If you put copper wire into drill, spin a few times without breaking, straight as an arrow, just saying
What alternative for copper wire??
aluminium? But copper is just better
@@FPVUniversity one more is the thickness of the copper wire matters?
Thank you, a big plus.
Thank you
Great job!
Suscritooo amigooooo un abrazo gigante
Thanks
seems to be difficult enough for frsky to fuck up
yeah sure with your hand on the connector will never show the true potential...