Mavic Antenna Tower?

[junyong]

Sorry if this has already been discussed but how difficult would it be (technically and financially) to incorporate a raised radio tower into the Mavic's RC? Personally, if I could get my point of transmission about 15-20 feet higher with a fixed structure I could clear most major obstructions and achieve massive improvements in range without having to fly higher (I reach the 400 ft ceiling fairly quickly before the signal cuts out). I'd imagine this would entail replacing the existing antennas with something that can adapt to a long coax with an SMA plug. Would such a coax and exposed external SMA connection kill the delicate signal?

If it worked, this would also be great for flying from indoors or setting up an antenna on top of a car and flying from inside without bad angles.

And I'm 99.9% sure I know the answer to this one is no but would something like this be possible without modding the original antenna. Like a repeater that communicates to/with an external antenna, possibly even boosting the signal along the way?

As always, I appreciate all the entertaining and informative discussions shared here.

 

[tictag]

Without modding the stock antennas? I've only seen parabolic reflectors that can be fitted around them.

There are antenna mods for your controller that purport to provide signal amplification. The one I watched (on YouTube) ended up with the two stock antennas being replaced with two R-SMA connectors, which you could then I guess extend with low loss coax. Remember that the actual length (and polarisation) of the transmission antenna needs to be chosen very carefully e.g. 1/4 dipole or one full wavelength at the transmission frequency.

 

[quibbler]

TL;DR: You're trading signal power for antenna-height; but it's almost always worthwhile if you think you need it.

• a directed, radiated 1 watt on a tower will reach (many times) farther than an omnidirectional 10 watts behind ground clutter.
• every inch of cable getting to the antenna, and each connection attenuates the RF a little, so quality counts! (both workmanship and using the best cable/connectors for freq.)
• there's no useful way to do this without modifying the remote, but there's no reason not to do so (except warranty, breaking it, or violating RF regulations).
• in theory, you'd attach to the delicate SMT(?) connectors on the board and run pigtails, and switch to a more robust, SMA connectors, preferably ones you can attach easily to other shorty antennas etc. (This is exactly what MaxxMod does btw.)
• in your bag-o-antennas, you keep one with a long cable going to your antenna of choice (if you're going to the trouble, >30° directional would seem to be preferred.

With a non-consumer product: “hell yes do it!”- but in a consumer product (type-accepted by authorities (FCC)) every component is designed together to stay below some maximum output (ERP Effective Radiated Power) as measured at the antenna, and in the loudest direction, not at the final amplifiers. This is why sometimes you'll hear people call after-market WiFi antennas 'illegal'; they're more effecient and actually emit more power because they waste less RF energy than the type-accepted stock antennas (and in many cases focus it all in one direction). You're asking to do the opposite; waste a little more RF energy from a fixed-power amplifier to locate the antenna ins a much better location which, in practice, is almost always a good tradeoff if you have a ground-clutter issue, or if you want a truly 'fixed' ground station that doesn't depend on 'how you hold it'.

Example:
1.4w amp ••> 33% attenuation from stock parts ••> .93w ERP
1.4w amp ••> 10%pigtail •> 30%cable •> 5%connectors ••> .84 ERP

...but .84w at the top of a 20' tower achieving unobstructed line-of-sight is much better than .93w at chest-level waving around as move. (Meanwhile, if you use a unidirectional instead of omnidirectional antenna, you can easily multiply that ERP past the stock .93w.)
Read up on antennas generally to learn more and always pay attention to polarization, the Mavic and remote's antennas are vertical!