Crossfire Antenna: Mini Immortal vs. Immortal T V2

by Oscar

The Mini Immortal T Antenna is now available for TBS Crossfire receivers. These antennas are super tiny and should be great for micro quads such as Tiny whoops and “Toothpicks”. Let’s compare its performance to the Immortal T V2.

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Where to Buy?

Mini Immortal T

Immortal T V2

What’s Special?

So how tiny the Mini Immortal T is compared to the full size Immortal T V2? Here are the measurements.

Immortal T V2

  • Dimension 145mm tip to tip, 90mm long
  • Weight 3.5g

Mini Immortal T

  • Dimension 55mm tip to tip, 45mm long
  • Weight 0.9g

As you can see even both antennas use U.FL connector, the Mini Immortal is significantly lighter and smaller.

Thanks to the compact form factor, it’s great for micro quad. Here I am installing the Crossfire Nano Receiver and Mini Immortal Antenna in the Skystar Talon.

Performance Testing

As I don’t have the equipment to test these antennas scientifically, I sent them to my friend “Krohsis” from IntoFPV.

To sum it up, based on Krohsis’s test, both antennas should work on both 868MHz and 915MHz (CE / FCC frequencies), but the frequency tuning of these antennas are completely different.

The Immortal T V2 would work better at 915MHz than 868MHz, and for the Mini Immortal T, it would work better at 868MHz than 915MHz.

Here is his original reply and findings if you want to know the detail:

Testing Methodology

Below are the results of the testing I did for you. I tested both antennas at 915MHz and 868MHz, the results were fairly interesting.

Before I list the results of the testing, I wanted to cover some methodology. I tested the antennas both inside my shop and outside away from any buildings, etc. Neither location changed the readings of the antennas.

Some antennas do get different readings when you change their operating environment, but not with these two antennas. Also, some antennas change their readings if you touch the feed-line. The mini immortal antenna was like that. I could change the readings by touching the feed-line with just my fingertip and if I squeezed the feed-line it would change more. Touching the feed-line on the big antenna there was no change. Obviously touching the u.fl or moving the antenna so the u.fl moved on the analyzer would change readings so I was cautious not to do that.

Reading Results

I’m unsure if you know how to read the analyzer so I will explain it. There are two pages you can select for each reading. The main page is all numbers and page two is a graph.

On the main page at the top is the selected frequency. This is the frequency that the measurements are based on. The critical numbers below the frequency for this test are in purple which is VSWR, and the yellow which is Signal to Noise ratio (SNR). The other measurements are resistance, impedance, reactance, etc., not important for this test.

On page two, the graph page, there is a small yellow diamond. That is where the selected frequency is located on the graph and the red line is where VSWR is for a particular frequency. The scale for the graph is set by me, for this test I set it from a low of 814mhz to a high of 1015mhz, making each vertical blue line segment on the grid about 28mhz per. The purpose of the graph is to see how the readings on the main page line up with each other for a given frequency. For example, sometimes VSWR will be lower at a different frequency than the desired one. The graph allows for seeing where the readings on the main page are in relation to each other, and where the antenna resonate point is located.

Testing Immortal V2

As you will see below, the larger Immortal T V2 antenna is very serviceable from 868mhz through 915mhz and ended up resonating at 922mhz.

Measurements at the resonance frequency:

I don’t know if the big antenna is sold as a 915mhz antenna or an 868mhz antenna. I know the V1 of the Immortal T is tuned around 900mhz, with the thought being in the middle of the two frequency standards it should work fine on both frequencies. But this V2 version of the Immortal T seems more suited to 915mhz as it resonates at 922mhz.

But as you can see it would work on either 868mhz or 915mhz, just better on 915mhz, with better VSWR and SNR readings, with the best readings and resonate point at 922mhz. That is quite distance from 868mhz.

Measurements at 868MHz:

Measurements at 915MHz:

Testing Mini Immortal T

The small antenna is different. Here are the measurement at the resonance frequency:

As a 915mhz antenna its performance would be very reduced over 868mhz. I believe this antenna was tuned specifically for 868mhz.

For what this little antenna is it really is doing a pretty darn good job. VSWR is a little elevated, but not so bad as to cause any real problems.

And the SNR is pretty darn good all things considered. It would be interesting to field test it to see what kind of range is really possible even though it was never intended to be a long range antenna. I think it would perform really well, at least the testing seems to indicate that.

Measurements at 868MHz:

Measurements at 915MHz:

That’s it! Any question please let me know in the comments.

Happy flying.

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Joqiz 2nd August 2022 - 4:48 pm

You van still measure what part is the active part, if you messure resistance between ground on connector and both sides the resistance of the active part is higher than the ground part because there is a little coil in between that is .1 ohm. Maybe it helps

Jim Leffler 13th October 2020 - 11:09 pm

I believe FPVCycle explained their antenna I has been retuned. Oscar did a great review from the only antenna at the time.

Brando Von Fronkenstein 31st July 2020 - 9:48 pm

The awesome dudes at FPVCYCLE designed this antenna. And made by Mr. Anderson and TBS does not claim this antenna as their own. I have like 6 or 7 of them. Awesome little units.

Bob 11th July 2020 - 6:06 pm

This is a really helpful and fantastic write up. We would really appreciate it if you mentioned where the antenna actually came from and where it was originally made available. Originally, this antenna was a project between FPVCycle and Michael Anderson. FPVCycle came up with the idea years ago, Michael was an avid user of micros and had some knowledge of the area. We asked him to do some tests and then asked TBS to make it for us.

Please mention makers and producers when available. If for nothing else, just a sense of pride for them so they are encouraged to continue. Thanks.

Oscar 12th July 2020 - 11:20 pm

I bought them from an RC shop. Wasn’t sure who designed them, thought TBS did, they look tiny and interesting so I asked a friend to test them for me and see if they are any good.
Thanks for the info though!

Mike. 1st May 2020 - 1:20 pm

It is totally incorrect to describe the yellow figure as “Signal to Noise ratio (SNR)”!

It is clearly labelled on the display as S11. The S11 figure is the reflection coefficient and is a measure of how much power is reflected back to the transmitter from the antenna. If is directly related to the VSWR reading.

VSWR can be calculated from S11 by:

VSWR = (1 + S11) / (1 – S11)

Describing S11 as signal to noise ratio is fundamentally incorrect and you should really correct the article to stop spreading incorrect information.

Josh 18th March 2020 - 2:18 am

I got a bunch from FPVCycle too- love them I use them on all builds now.

Clif 17th March 2020 - 9:01 pm now has the Minimortal antenna’s back in stock. That’s where they originated from to begin with.

David 5th February 2020 - 1:53 pm

Hugo, you can buy an adapter so you can use it with your R9 stuff, but then your lead would be longer so that ‘might’ be an issue…

Hugo Bokhorst 4th February 2020 - 3:13 pm

I bought 8 of them from FPVCycle, but found out they don’t fit my R9MM OTA’s… now I’m considering to buy the Tango 2 and a bunch of CRSF nano’s and switch over my whole fleet… especially since I’m in the EU and need 868MHz. I already hate my R-XSR’s because they introduce lines on my video feed when using telemetry (on micro’s and toothpick’s there’s no way to keep things far apart), so I switched most micro’s and TP’s to XM+ to at least get RSSI without telemetry, but I miss the audio warnings on my X-Lite. Does the CRSF system with its telemetry also make lines and noise on the analog video feed when close by (the reason to go Mini Immortal is for micro quads..)?

I will also miss the 1W output of the R9M Lite Pro.. The Tango 2 only does 250mW! How does that compare?

Oscar 18th February 2020 - 12:07 am

Crossfire and R9M both operate at the same frequencies, so it has no difference in interference to your video.

Christoffer Gylin 7th June 2021 - 10:38 am

Yes, I’ve had problems with wide lines in the fpv feed when using minimortal, and they dissapear when I turn off telemetry

Mantas 4th February 2020 - 11:00 am

Mini antenna SWR is 2.5 ! Loks like RX can start accumulate heat ? Right?

Ely 3rd February 2020 - 6:15 pm

You can buy the mini mortal t at, although its out of stock because of CNY.