I keep hearing about LR quads. So I am using typical freestyle quads with either ELRS single or dual antenna Rx or TBS crossfire with Immortal T antenna. I studied Oscar Liang and Bardwell content. I go out flying and monitor the Betaflight LQI and RSSI dBm readings. And just about when I see that the readings are starting to deteriorate, BAM! Failsafe. LQI is sitting at 100, then it's bouncing around 90, then it's flashing 20 and gone, and I feel like I have hardly moved. Same with RSSI dBm, I just spent 4 hours over two days searching for 6" quad in tall grass. I found it but looking back at the goggle feed when my LQI went south the RSSI actually stayed above -90 dBm all the way down. With -115 to play with I thought I was safe? Now I am talking about a quad at high altitude, unobstructed over flat terrain and less than 1.5 km away, probably closer to 1km. That's nothing.
That is one recent example but there have been others. So I fly with the fear that the instant my readouts begin to deteriorate I have to turn back. 
Maybe real LR quads need different antennas, maybe I need to start using directional antennas on my goggles. Or maybe I just don't get it. 
This thread could also go in the beginner section because I am not really trying to fly Long Range, I am more trying to fly within the range constraints of the equipment I am flying.
A penny for your thoughts?

it shouldnt be the main issue, but what settings do you use? 150hz 250mw?

show us your antenna placement on the quad please
it might be something like antenna placement and interferences, a noise issue. tbs linkquality can and should be way better

I agree with Huggy, we need to see  your antenna placement.  

Make sure your TX antenna and RX antenna are polarized the same.  Make sure there is no battery, carbon fiber, or items that block RF are blocking the signal from TX to RX.  I could go on, but post up a pic of your setup.

Secondly, the Immortal T is a crappy antenna right from the store.  The antenna is tuned to between the European 868mhz and the USA 915mhz.  They do this so they only have to make one antenna for both frequencies.  The end result is an antenna that is not very good for either frequency.  I think I have a post here on the forum where I show this with an antenna tuner.  The Immortal T works fine for acro, but its limitations start to show pretty quickly as you get out a bit.  I know some LR pilots have reasonable luck with the Im-T, I never did.

Yes, directional antennas on your goggles are important if you are looking to go out at LR distances.  Also, not all goggles are equal in their ability to capture a signal, but all goggles should get  you out past 1-1.5km.

So post up a pic of your quad and we will take a gander.

Thanks guys. Im off for a couple days but when i get home ill post pics. But i mount my immortal t’s horizontal across and under the rear motor arms. On my Boxer Tx I am using the stock TBS antenna with the older 250mW module.

If you only have one antenna on your quad, forget horizontal polarization if you want to fly LR. The primary antenna must always be in vertical polarization, and of course on the Tx as well. The antenna must generally be as far as possible from the quad components, preferably at least a quarter of a wavelength away, and must not be shielded by the quad components. The further the better...

Hmm, would poorly aligned or placed antennae contribute to the sudden loss of signal that I keep experiencing? Or to put it another way does optimum antenna placement give the pilot more time to see the signal degrading and turn back? The goal is not so much to extend the range but rather to slow the rate of signal loss.

(08-Feb-2024, 03:56 AM)husafreak Wrote: Hmm, would poorly aligned or placed antennae contribute to the sudden loss of signal that I keep experiencing? Or to put it another way does optimum antenna placement give the pilot more time to see the signal degrading and turn back? The goal is not so much to extend the range but rather to slow the rate of signal loss.

Frequently signal loss can be sudden.  But with that said it can be slow enough depending on environmental conditions, and speed of the quad reaching limits there can be enough time for a warning.  Most of the time when I have begun to lose signal it happens very quickly.

Vertical polarization is best for this hobby.  In a strictly RF world horizontal polarization is superior, but in this hobby vertical is the way to go for LR.

Do the following tests, it will help you find out where the problem is. For the tests, you need an open area where there will be direct visibility for kilometers without obstacles, no trees, buildings, etc, without any other rf transmission, so preferably somewhere outside civilization.

The first part of the test will give you information about whether your antenna is shielded by the quad component. In the current configuration with horizontal polarization, fly the quad straight from your position in a straight line at a distance of at least a kilometer so that the Tx and Rx antennas are parallel. This ensures that the antenna of the quad cannot point to your position with its tip. In the OSD, watch the "RSSI DBM" parameter, this value should slowly decrease, in any case there should not be any jumps in the value, the value itself is not important now, no jumps. Don't come back in a flat turn, instead do a split-S, this will ensure that again the tip of the quad's antenna is never pointing to your position. During the split-S for return, the possible shielding of the quad components will be manifested separately, the influence of bad polarization of the antennas will not be noticeable. If your antenna is too much shielded by the quad, the "RSSI DBM" value will drop significantly during split-S, if the antenna is shielded acceptably, the drop will be small. When returning in a straight line, the "RSSI DBM" value should be just a little less in overall than when it flew away from you, and slowly increasing as you come closer to your position, I assume you have the antenna on the back of the quad.

The second part of the test is about polarization. The only difference from the first part is that you will be turning back in a flat turn and at one point the antenna tip will be pointing directly at your position, at which point you should notice a short-term deep drop in the "RSSI DBM" value. The second test is more of a demonstration, as we wrote earlier, horizontal polarization with one antenna is physical nonsense suitable only for close range, where it is simply not necessary to solve it.

If you have jumps in the "RSSI DBM" value not caused by the phenomena described above, you have a problem elsewhere, faulty Rx, faulty antenna feet, wrongly connected antenna.

For LR, in the case of antennas of the monopole or dipole or sleeve dipole type, two antennas are always needed on the quad, at the back with a vertical orientation, at the front with a horizontal orientation, the rear vertical antenna must always protrude well above the quad so that it is not in any way in the direction back and forth shielded quad components. The front horizontal antenna solves situations when turns or acro turns are made, when the rear vertical antenna will not be in vertical polarization, and in the turn the front horizontal antenna will go to vertical polarization. The transmitter on LR always has an antenna in vertical polarization (I am not dealing with Gemini's case here now).

Hope this helps.

The photo shows a quad with an ELRS dual receiver. In front is a white antenna in horizontal polarization, stretched forward and down as much as possible so that nothing shadows it. Well, the main thing is the rear long antenna, which is in pure vertical polarization when the quad is flying in tilt of about 30-40 degrees. In this tilt, the antenna protrudes even higher, and it is definitely not shielded by anything, regardless of whether I am flying towards or away from myself. The same applies to the front antenna when the quad in this tilt, the antenna is as low as possible and outside the components of the quad.

I agree with much of Momo's comment, but there is one exception that is not correct.  Momo said "For LR .....two antennas are always needed on the quad".  This is completely untrue.  I've got over 1450 LR flights with quads and have NEVER ran 2 antennas and never had a problem at all.  IF you blend acro and LR at very long ranges there could be a need for a second horizontally polarized antenna that will become vertically polarized during rotation in acro.  But the second antenna isn't there for long range, it is there for acro.

OK, good point ...
It is the method of return - turning back at the end of the road, on top of the mountain 10 km away, that is the key thing. Not all of us turn in a flat turn where vertical polarization is functional ... When you do a deep dive, you don't start with a flat turn. That second antenna is crucial, just for those moments when one wants to avoid initiating GPS Rescue and ruining the shot. And sometimes reflections also help when flying, for example through a canyon, every antenna is good. I also have an LR quad with one antenna in vertical polarization, I have tried it, you can fly with it and pull the halves of the ass when turning back. It's somehow uncomfortable for me, I've never had a problem with two antennas and I'm at peace...

I think do what works for you, is as good a concept as any. If one antenna works for one person and two for someone else, then both work, but usage cases are probably different. If you fly completely flat, then do a yaw spin and fly back, then maybe one antenna is enough. If you fly 5 km out to some mountains and then shoot down the sides of them, hugging the terrain, maybe a different configuration is better.

I suppose in some ways, mountain surfing is probably more Cinematic than LR, but it takes parts of both to do it.

I don't do LR like you all do, but I do find this part of the board quite interesting.