Antenna mods

MacIak · Sep 30, 2017

Brojon said:
Sorry but there's no way 42 mw is going out as far as it does.
Someone measured incorrectly or there was a feed mismatch with the modded cables.
I keep saying that there are matching factors at play that it would be nice to have tech details on.
Microwaves are sensitive to impedance mismatch. Just plugging into a meter isn't useful information without knowing how it was loaded.
I still think the "boost" mode is for the CE (EU) folks to get teh same power as US users. I may be wrong but I believe that was what I saw when I looked way back.
I'll see if I can revisit and look closer.

Aside from the numbers @CyberNate his explanation is quite accurate. The config file mod can be used to increase output beyond FCC mode. The output of the remote is fixed and can be measured, the output of the bird is dynamic and hard to measure (for amateurs like myself). Also hard to determine if also the bird side gets overheating issue as power increases with weakening signal.

mavicpro1000 · Oct 3, 2017

The mavics receiving antennas are linear polarised. Why are people using those circular springy eggcup things.??7

MacIak · Oct 3, 2017

mavicpro1000 said:
The mavics receiving antennas are linear polarised. Why are people using those circular springy eggcup things.??7

Totally correct you are BUT....These springy eggcup things actually work better than any other upgrade antenna (Unboosted. When boosted there is little to no difference). I ve tested them myself as well being sceptical about the polarization.

Brojon · Oct 3, 2017

mavicpro1000 said:
The mavics receiving antennas are linear polarised. Why are people using those circular springy eggcup things.??7

Because the MP might not be oriented perfectly up and down. Circular polarized eliminates that as a concern.
That said the springy looking things don't give me a warm fuzzy at all - a helix antenna should be longer than that at 2.4 Ghz.
If memory serves me the "length" of the helix in the directional plane should be about proportional to the # turns and coil spacing. Coils are typically spaced 1/4 wavelength apart so each coil should be about 3 cm apart. It should be obvious the design doesn't appear to adhere to this spacing meaning gain will suffer. A properly designed helix with only a few coils at 1/4 wavelength spacing would only give about 10 db gain to begin with so with narrower spacing it will be far less.

Brojon · Oct 3, 2017

MacIak said:
Aside from the numbers @CyberNate his explanation is quite accurate. The config file mod can be used to increase output beyond FCC mode. The output of the remote is fixed and can be measured, the output of the bird is dynamic and hard to measure (for amateurs like myself). Also hard to determine if also the bird side gets overheating issue as power increases with weakening signal.

Agreed but as I said the practical difference between 1 and 1.5 watts is insignificant. I'm not sure what you mean about the output being "dynamic" unless you are referring to environmental effects while flying in the real world.
Anyway - I'm not trying to argue - just stating the facts as presented by DJI and the FCC for power output. In the case of CE limiting power to a ridiculous 50 mw or so the FCC boost is *huge*. That additional 1/2 watt over a full watt isn't worth it from a risk standpoint IMHO.

Adamcain112 · Oct 3, 2017

Has anyone tried Titans Control antenna, and what's the differance between this and the Cyclone?

mavicpro1000 · Oct 3, 2017

We need IBcrazy to test these antennas!!

MacIak · Oct 3, 2017

Brojon said:
Agreed but as I said the practical difference between 1 and 1.5 watts is insignificant. I'm not sure what you mean about the output being "dynamic" unless you are referring to environmental effects while flying in the real world.
Anyway - I'm not trying to argue - just stating the facts as presented by DJI and the FCC for power output. In the case of CE limiting power to a ridiculous 50 mw or so the FCC boost is *huge*. That additional 1/2 watt over a full watt isn't worth it from a risk standpoint IMHO.

Dynamic meaning that the bird side increases tx power to a maximum when it senses signal gets less. So nearby the output is lower.

Adamcain112 said:
Has anyone tried Titans Control antenna, and what's the differance between this and the Cyclone?

The Cyclone is a boosted Control. Very good antenna for signal improvement.

Brojon · Oct 4, 2017

MacIak said:
Dynamic meaning that the bird side increases tx power to a maximum when it senses signal gets less. So nearby the output is lower

Huh! Didn't know that. It would certainly make those low power numbers mentioned make sense if they didn't have the bird at any kind of range. Clever engineering as a battery saving method.

MacIak · Oct 4, 2017

Brojon said:
Huh! Didn't know that. It would certainly make those low power numbers mentioned make sense if they didn't have the bird at any kind of range. Clever engineering as a battery saving method.

Yep. Needed to check the output of the system and used a spectrum analyzer. The bird side did not make sense and noticed output was increasing if rc was moved several walls away. I think @beanbubba had similar findings (put one of em in de microwave or somethin') blocking the signal.

Brojon · Oct 4, 2017

LOL - a SA is a little overkill - no field strength meter?
(wish I had a SA laying around)

MacIak · Oct 4, 2017

Brojon said:
LOL - a SA is a little overkill - no field strength meter?
(wish I had a SA laying around)

Haha!! I do not own one..initial readings from the strength meter did not make sense ( I thought, note im from the 3d heli corner.. so normally never need to check signal strength with good ole Futaba where output=output) so I took Mav to work. Subdivision Comms have a kickass shiny SA and had them give it a go!

mph300 · Oct 12, 2017

Brojon said:
Agreed but as I said the practical difference between 1 and 1.5 watts is insignificant.

No radio wave expertise here but common sense says 50% increase in transmit power would be significant. Am I missing something?

Brojon · Oct 12, 2017

Yeah - the inverse square law that says power drops off by the square of the distance.
So double the distance cut the power by a factor of 4. So if you have 1 watt at 10 meters you have 1/4 watt at 20 meters, 1/16 watt at 40 meters. So a 50% increase amounts to very little in reality since you need to *bump* power by a square factor. So if you have 1 watt at 10 meters to have twice as much power at 10 meters you actually need to 4x it = 4 watts. that 50% increase is also reduced by the square.

mph300 · Oct 12, 2017

This is exactly why I read this forum and many others. I try to learn something every day. Check.

lolo780 · Oct 14, 2017

Plan A is extended legs that position the stock antenna as far down as possible, and vertical. Plan B would be relocate the antenna entirely. Thoughts?