MiniMortal T at home - can't you just shorten a Immortal-T?
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- čas přidán 28. 01. 2020
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FPVCycle MiniMortal-T is an interesting option of TBS Crossfire users: being roughly 1/3 of a length of a "full-size" Immortal-T, it allows for just enough range to fly freely with not-long-range kwads like toothpick and even 5" racers. Now, the question is: can you make an FPVCycle MiniMortal-T from full-length Immortal-T by shortening it? Can you convert a 1/2 wavelength dipole to a 1/4 wavelength dipole? Does even 1/4 wavelength dipole is a real thing? - Věda a technologie
![☀ Крошечная антенна на 900MHz - обманули физику? [TBS Minimortal T]](http://i.ytimg.com/vi/ISNthKMqSH8/mqdefault.jpg)
![☀ Крошечная антенна на 900MHz - обманули физику? [TBS Minimortal T]](/img/tr.png)
![☀ Делаем крутую антенну своими руками: инвертированный VEE диполь [Vee Dipole DIY]](/img/n.gif)
Thanks! You saved me an antennae and some headaches!
Pawel,
My wife enjoys listening to you as her grandfather was from Kuty, Slovakia and your English is much like his was. I enjoy the content. Keep your reports coming.
Joe
Thanks mate!
Great testing, Pawel! 😊
About that antenna, if I'm not mistaken it's made by TBS.
made, yes. But they very precisely say that they did not designed it!
Sorry for the antenna but good test, Pavel!
Cheers for that Pawel.
I’m no electrial engineer, but it seems to me that a 1/4 wave monopole made from a piece of coax would be smaller and lighter than a full Immortal T, and should work almost as well since monopoles and dipoles have the same gain. The monopole is just somewhat less omnidirectional. I might be wrong here, but I do plan on experimenting with this after I build a crossfire micro quad. Thanks for all of your wonderful videos. I have learned a lot from you, and I am very grateful for all the work you put into them.
Slightly off topic: Do you know which lead is the active element and which is the ground in a Immortal T antenna? Want to mount mine with the active element UP and the ground DOWN. Can't figure out which is which though. Both leads seem to have continuity to the ground on the Ufl connector, which doesn't make any sense to me if this is a standard dipole.
How can you tell which is the active element and which is the ground plane on the immortal T?
Hey Pawel, I think we all looking for a better way as mounting the 160mm antenna vertically on a quad...
What about a 868/915mhz spring coil antenna as an alternative? Did you ever thought about that?
Would be interesting to see how a spring coil Lora antenna performs.
Would a 2.4 ghz antenna at full resonance be good range?
It wuld be great if Bob can send you one of those minimortals for test.
Thank you Pawel. I'm an engineer and I trust you :-) But, what do you suggest for whoop style quad with 900mhz receivers?
the whole idea of w whoop with a 900MHz radio is somehow stupid to me. Even the real small Immortal-T from TBS is still kind a biggish for whoops
Can I trim about 2mm off each end of the immortal T? It’s just a bit too long.
If you want to shorten a 1/2 wave dipole your choices are limited yes as you said a coil to add inductance will work or a capacitative hat at each end of the elements but probably the simplest way is to loos half the antenna is go for a 1/4 ground plane the ground wire can run any way you want including along the feed line as long as it is insulated. also remember shortening an antenna with coils or capacitors will heighten it.s Q factor resulting in a narrower bandwidth.
Pawel, would it make sense to put it on a RF meter to see how does it receive and compare it to regular dipole?
You have access to equipmnent like that?
@@FPVUniversity No, sadly not :( only RF meter which is not sensitive enough...and You have one too I guess
Hi there .. thank you for your very informative videos ... can you make a video that replaces or solders the the mortal T antenna diecting to the receive itself??? ... my antennas are not broken ... but the connector on the receiver is broken - sso I am asking if it is POSSIBLE to solder the antenna directly??? Thank in advance.
Of course you can do it. Just remove the connector on receiver and antenna and solder it precisely
ok now :D real world testing :D I did this on R9 but not with a dipole....took my quad and replaced R9 antenna with some 2.4ghz spares....trimmed it to 1/8 wave length of 868 (did not add counterpart so it was no dipole)...then turned off telemetry so it was hopefully only receiving....flown more than 1000m with RSSI nearly identical to what a 1/4 dipole had.....no idea why then
I'm trying this.... why turn off telemetry though ?
4:00: What are you measuring there?? You did not go from the middle of the antenna. And you did not end at the tip of the antenna. Looks like there's still 1-2 mm to the end.
I agree, wasn't really scientific. But the tuning was so far of that the few mm don't matter
@@VincentFischer Maybe. Microwave transmissions are voodoo magic sometimes! Even what seem like subtle changes can have drastic effects.
A wet noodle would be sufficent as antenna for 900MHz for micros (which the fpvcircle antenna is targeting I think) considering the flighttime. Could you maybe look into these 900Mhz pcb LTE antennas found in smartphones? TBS has them in their shop and branded as super duper "xf race antenna". Available on aliexpress for cents or 6usd plus shipping from tbs.
Vincent Fischer - I had zero luck with the XF-Race antenna. Horrible range and penetration for me but I’ve seen others use them with great success. But I removed the ipex2 ufl pigtail and added the smaller ipex4 ufl pigtail for use with an R9MM receiver so that might have had an effect on performance but I don’t see why it would.
@@sketchpv3080 You soldered coaxial cables together or did you crimp the connector on? Sounds like a real challenge. Might as well desolder the connector from the R9mm and solder the antenna directly. I'm sad to hear that they didn't work well for you, I thought it's the only viable solution for micros :(. So whats left beside having an antenna dangling behind our micros half the size of an immortal t
The length of the cable between the antenna and receiver/transmitter needs to be tuned to the wavelength too. (not just the active and passive antenna elements)
Sasha Kruse Grim - That info is much appreciated. I couldn’t figure out why the signal strength was so low. I thought perhaps I flexed the PCB enough to break the element inside but it makes sense now.
How about the immortal L?
Coil loaded dipole like the ones that come with the full size rx wood be nice with a ufl plug so I can just pop it on my quad and fly
🥃cheers🍻
I don't dare, nor intend to question the results of your test and measurements, but from experience I can confidently say that an Immortal T chopped the way you did, still has a far superior range compared to the Minimortal antenna, not to mention the durability.
I need to admit here (not without some guilt) that I have been using such an antenna on my 2 TH Freestyle kwads and been pretty happy so far. Previously I had tried the Minimortals, but a) the range sucked, b) they were too fragile - I had mine fairly exposed in order to get maximum of range and it didn't take a big crash to snap the 'T'... The Immortals on the other hand live up to their name 🙂
Now that Express LRS is here, I'm thinking about switching to it, but I'm also hoping that seeing how popular Express LRS has become, TBS also releases a sub-nano Crossfire rx with a ceramic antenna, because I love the firm factor of my Tango 2 and don't really want to add an external module to it...
If you want to shorten the antenna just make a coil with the wires.
+1👍
i'm pretty sure this is exactly what the minimortal t is, you get a colossal loss of range, 2 to 4km instead of 40+km, but still pretty functional.
You would get the same effect just putting a random length of a wire instead. Range depends on the amount of power put into the air and receiver sensitivity, not antenna length
@@FPVUniversity That's what she said.
I'm pretty sure it is just a terribly tuned antenna. czcams.com/video/J2kghRbc1MM/video.html
Honestly what is the point of having shorter antenna? 🤔 Seems like we looking more stylish antennas than the quality ones. It does not make sence just use a proper sized antenna's and there will be no problem with reception 📶
well, when antenna is longer than the quad itself it get problematic :)
Got myself r9 slim+ so far no problems on super 8 antenna and my quad is 7 inch seems all good so far :)
Well my 2,5" toothpick isn't happy with the Immortal-T you know? And he doesn't mind not being able to fly 10km+ if he could get some shorter antenna :)
I got myself a tiny 5cm antenna today for the crossfire. I will put it to a test soon and will let you know how it works out.
@@Umarluch Their half dipole works great on toothpick builds. Just install it so that each end is on an arm with a ziptie and heatshrink, like we did for 2.4GHz. Yes, the carbon will block some in the middle, but I've flown about 1/2 mile out and never went much under 80 for my RSSI value in OSD, brief drops into the high 70s during turns and flips.
But crossfire has such good error correction so it work even if you unplug the antennae...😎
am... really? ;)
Nope...
Why would you need to anyway, if it's a mini fly it round your head quad..?...Just install a 2.4g reciever....ffs.
What is the point of a shorter antenna if you lose range. Might as well just use 2.4ghz🙄. If it's a question of more latency with FrSky 2.4ghz then you should have bought FlySky...lol
they are mostly for small toothpicks and whoops, where size and weight matters