Aircraft Antenna Mod

[beanbubba]

So this is the first design. Please come with suggestions for improvements. I am looking for an Arduino programmer to embark with me on this mission, please holla at me.

View attachment 18167

Hey wynnhoj,

I have worked with rasberry pi's in the past, but no experience with Arduino. Send me the model number you are considering and I will get one and start hacking at it.

 

[beanbubba]

So this is the first design. Please come with suggestions for improvements. I am looking for an Arduino programmer to embark with me on this mission, please holla at me.

View attachment 18167

When considering breaking distance records, this antenna system will far exceed the battery capacity. I was hoping (when time allowed) to craft a battery jettison system something like this:

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Maybe this could be part of this overall project??

 

[wynnhoj]

Do you have any initial estimates on overall size and weight?

Oh I do; L75 x W55 x H35mm (without antenna mounted) and about 100-200g depending on final decision on motor.

Currently I'm working on the code and waiting for parts from Asia.

 

[wynnhoj]

Hey wynnhoj,

I have worked with rasberry pi's in the past, but no experience with Arduino. Send me the model number you are considering and I will get one and start hacking at it.

Oh cool. I have managed to get help from a professional programmer via Freelancer. I was planning on using the Arduino Pro Micro with a external GPS + Compass module that will mount on top of the drone.

My main consideration right now is choice of motor. I have gone from micro-servo to stepper and now to geared DC with encoder. I really would like to use a cheap micro servo but they only turns 60-180 degrees and that sucks. Sure I could 3D print some spur gears but I would like to keep this as simple as possible.

 

[ZeeKodadii]

Oh cool. I have managed to get help from a professional programmer via Freelancer. I was planning on using the Arduino Pro Micro with a external GPS + Compass module that will mount on top of the drone.

My main consideration right now is choice of motor. I have gone from micro-servo to stepper and now to geared DC with encoder. I really would like to use a cheap micro servo but they only turns 60-180 degrees and that sucks. Sure I could 3D print some spur gears but I would like to keep this as simple as possible.

Just a thought since the mavic uses gps couldn't the Arduino get the location from that so you don't add a external gps to the bird? Or just use the mavic own gps modular for the tracker?

 

[Mavman]

I’m very intrigued by this. Very curious on how well the simplest version of the bird-side mod works with the 2W amp, and would love to see a DIY guide for the layman! Great job beanbubba you’re a pioneer! I’m also very interested in your pole mounted antenna... much to expensive for me to indulge, but I’ve found myself daydreaming of something i could quickly slap onto the roof of my vehicle to give some extended range!

Also, wynnhoj, I love that you’re seriously trying to do a motorized antenna!!!!

One other thing, Beanbubba, I’m curious how much energy those rear leds use.

Ive been tempted to do battery mods, and controller mods, but have held off. It looks like this bird side amp mod may be the best bang for your buck, AND the most minimalist, portable approach.

Great job all around - wish I could contribute more. If anybody could use something specific written in python, glad to help, but not sure that will be useful.

 

[beanbubba]

Oh cool. I have managed to get help from a professional programmer via Freelancer. I was planning on using the Arduino Pro Micro with a external GPS + Compass module that will mount on top of the drone.

My main consideration right now is choice of motor. I have gone from micro-servo to stepper and now to geared DC with encoder. I really would like to use a cheap micro servo but they only turns 60-180 degrees and that sucks. Sure I could 3D print some spur gears but I would like to keep this as simple as possible.

I think a ~120 degree servo should be just about right for an aircraft bottom mounted antenna (for the forward/backward movement). This would be perfect for long distance range runs where you only fly straight out and straight back.

Just a thought since the mavic uses gps couldn't the Arduino get the location from that so you don't add a external gps to the bird? Or just use the mavic own gps modular for the tracker?

Does anyone know if the mavic GPS module in the rear end uses standards based interface/protocols? If it is standards based, you would surmise that you could "tap" the data feed and integrate into your external controller/processor. But this is a whole lot of speculation and day dreaming until someone can unravel the mavic GPS particulars and publish them (if they even exist).

 

[ZeeKodadii]

I have been looking at this for couple of months it's a all in one.
Easiest and cleanest set up. but it needs a gps feed to work

Arkbird-AAT Auto Antenna Tracker System w/Ground and Airborne Module

 

[wynnhoj]

I have been looking at this for couple of months it's a all in one.
Easiest and cleanest set up. but it needs a gps feed to work

Arkbird-AAT Auto Antenna Tracker System w/Ground and Airborne Module

Yes, but thats for the ground station. My device will mount under the drone and direct the drones antennas. This enable the use of directional antennas on the drone. My oh my

 

[wynnhoj]

I think a ~120 degree servo should be just about right for an aircraft bottom mounted antenna (for the forward/backward movement). This would be perfect for long distance range runs where you only fly straight out and straight back.


Does anyone know if the mavic GPS module in the rear end uses standards based interface/protocols? If it is standards based, you would surmise that you could "tap" the data feed and integrate into your external controller/processor. But this is a whole lot of speculation and day dreaming until someone can unravel the mavic GPS particulars and publish them (if they even exist).

I have thought about this as well. However from my understanding of DJI its not open source in any way. Furthermore the GPS + compass module is quite cheap and easy to implement (for my programmer). Or so he says anyways.

And if I use a dedicated GPS + compass for this device its entirely self-sufficent (except for the power input). This makes it cross-plattform. The only drawback I can see is: The pilot can't change location when the home-point has been set (More that +-10-20m?). But this shouldn't be a problem speaking from my own experience and the use of ground stations etc.

 

[ZeeKodadii]

Yes, but thats for the ground station. My device will mount under the drone and direct the drones antennas. This enable the use of directional antennas on the drone. My oh my

Wow interesting never thought of putting the tracker on the bird!!

Wouldn't it make more sense the other way around. Especially if you have the battery mod

 

[wynnhoj]

Wow interesting never thought of putting the tracker on the bird!!

Wouldn't it make more sense the other way around. Especially if you have the battery mod

Yes, the best way to do it is having antenna trackers on both the ground station and on the drone.

 

[wynnhoj]

Ok, so after a bit more prototyping and programming. My main concern have been getting the right precision of the antenna movement to the right weight, speed and dimension.

I have experimented with:
Stepmotors (Great precision, easy to code, really heavy, large, slow af, weak af)
Continuous servos w/ external potentiometer ( Worst precision ever)
DC motor with gearbox and encoder ( Large, poor precision)
180 micro servo with spur gears 2.5:1 (Good precision, fast, strong, lightweight, quite cheap)

In the meantime I am also experimenting on the case and internals design. Currently Im waiting for the 3D printer to finish up the case.

My estimates on specs:
Input Voltage 5-12v.
Dimensions: 50x70x40mm
Weight: <100g
Motor: Micro servo

Interface:
1 Power button
1 LED
1 Power input 2.1mm (Thinking about using a 3.5mm mono plug)
1 GPS antenna connector

 

[ZeeKodadii]

Can we get a sneaks peek of what you have so far

 

[wynnhoj]

Can we get a sneaks peek of what you have so far

Patience my friend,

 

[wynnhoj]

Could anyone help me with a delicate problem:

If we use a helical antenna with 60* angle i should mount it 90* because after 1km the base of the cone should be apprx 1.1km right? Only problem as I see it is that we get theoretically radio shadow within a radius of apprx 400m.

I found this illustration on the RC forums from the user Aspranger.
"Lets assume you had a combo of a CL and a Helical Antenna, then this image would show the areas, where you'd have video reception when using e.g. a 100mw tx like I do.

The green circle shows the area of the CL Antenna, using this, you can pretty much fly around your ground station in any direction, as long as you stay in the green circle. Even though the range is limited.

On the left you can see the Gain pattern of a 4 turn Helical. As you can see, you can fly further out, but the further you fly, the narrower becomes the area in front of you, where you'd have good reception of your video signal. With the 4 turn, the beam is very wide, thus it is suficcient, if the antenna points in the aproximate direction of your plane, or you can put the antenna on a fixed stand and fly everywhere in front of it, as long as you stay in the red area.

On the right you can see a high Gain pattern of a e.g. 9 turn helical. Due to the higher gain, the max range rises ( every 6 dbi the range is doubled ) but due to the strongly directional gain pattern of the antenna, you need to be carefull where you fly, or better have a spotter or an antenna tracker, pointing your antenna in the right direction."

 

[beanbubba]

Hey @JakeMaxxUAV my mod'ed mavic remote I bought from you a couple months ago has gone belly up. I just placed another order on your site for a $428 mavic remote. I sure hope this one lasts a little bit longer. I fully realize that I signed my life away for liability and hold no blame on your part. I just wanted to document this event in case it happens again.

 

[beanbubba]

Hey @JakeMaxxUAV my mod'ed mavic remote I bought from you a couple months ago has gone belly up. I just placed another order on your site for a $428 mavic remote. I sure hope this one lasts a little bit longer. I fully realize that I signed my life away for liability and hold no blame on your part. I just wanted to document this event in case it happens again.

While on the @JakeMaxxUAV band wagon, I have private and public messaged you 5 times for placement on the mavic range leader board. Can I assume you no longer manage that thread? Is there anyone else that can take over this role since Jake is now off the grid and non responsive??

 

[beanbubba]

I finally got back from my 2 week day job interruption and just started testing again. I had previously started tested the external sunhams amp's and I was not able to get a GPS lock or just barely. I moved the amp's forward towards the nose and immediately was able to GPS lock. These amp's obviously produce a near field EM interference to the aft located GPS receiver. Make note of this amp location if you want the GPS to operate at it's peak.

Lots more testing yet to be done and I look forward to what Wynnhoj dreams up next. I am shocked motor mouth hasn't been more vocal the last few weeks with makiak putting him in his place

 

[beanbubba]

Decided to take apart the factory antenna and check it out. Interesting design I have not seen before. They have what looks to be a reflector or similar device sandwiched right next to the antenna in the front leg. Whatever it is DJI came up with a fantastic result. From prior testing, the factory antenna is nearly as good performance as a high gain external 10 times its size.

I rerouted the factory coax cables from the antennas out the topside next to the amp's. I think this will be my final design and waiting on an SMA-U.FL adapter that is on order.