Parabolic antenna questions

[Cometstorm]

I have two parabolics. Tozo brand which I have used, and a set of Skyreats... yet unopened.

I get the seriousness of controller orientation being critical.

I was in an online discussion the other day, with a Phantom owner much more experienced than myself.

I was questioning why "compass" isn't a part of IOS Litchi, while it is with Android.

He said he always flies long distance parabolic, and uses the Map for orientation. He says it's just as good as compass for orientation.

But I recall another guy awhile back that said he ALWAYS uses compass for orientation... and hadn't used Map in ages.

What gives? Who is right? Of course, I'd like to see IOS Litchi compass for extended waypoints.

Am I wrong to assume Compass is better than Maps, strictly from the orientation issue?

On another note, I was flying a short distance higher altitude test flight the other day. Close to 1000 feet quicky.

I was surprised that I got a signal loss as such close distance, approx 550 feet.

Perhaps I lost signal because of the parabolic, near distance, and high altitude making antenna orientation difficult (unless I was holding the RC over my head? LOL)

Also, an "auto land" suddenly appeared nearly putting her into a tree, tho no such thing was programmed. I always set RTH.

Maybe I hit the HOME button too close to home point forcing the land command, but I thought I had no signal at that point. Maybe it had just re-acquired?

Also, I guess once you have a loss downlink, all subsequent flight data goes unrecorded until signal is back?

 

[Bad Andy]

I just picked up a liveMAX "parabolic" range extender (https://www.amazon.com/gp/product/B01LX9225B/) for my P3A but haven't had a chance to use it yet. I chose this particular one because of the convenient folding design and lack of complaints about alignment on the antennas.

Using a laser pen, I have noticed that the reflectors are not really parabolic! (EDIT: Or, the antennas may land a touch too close to the reflector, actually). Reading around, I find this a frequent complaint but have yet to identify a post saying "such and such reflector set definitely uses a correct parabolic curve". Not sure how much it matters - I think the actual antennas inside the plastic are loop designs. I can't imagine that the reflectors are going to make the antennas more orientation -sensitive unless the aircraft is behind you or way off to the side.

If the antennas on the aircraft are diversity sets, overall range probably also depends on the aircraft's orientation with respect to the remote controller antennas.

If you're doing lots of overhead flight I'd say to either point the antennas on the RC outward horizontally, or install a panel antenna that can be adjusted in that direction. And remember that the antennas in the aircraft legs are still vertical so limitations will remain. Warning: I've looked at YouTube instructions for installing a panel antenna and it's not for amateurs.

As for orientation preferences, compass vs maps, do what feels right for you. I don't think there's any right or wrong. On my car's GPS receiver, I prefer north-up and my wife prefers direction-up. And yeah, she really does turn paper maps around when she reads them...

Another thought about parabolic antennas, I wonder if they help prevent interference from tablet and cellphone radios, which would now land behind the reflector. I know that in my example, I use my iPhone as a WiFi hotspot and the iPad Mini connects to the WiFi for Internet access. Between that and NYC being so radio-dense, it seems very hard to make the RC happy about its signal quality. I also just applied the "hack" to increase channel variety so hopefully that will help a bit.

 

[nwcove]

if you

View attachment 88155 I have two parabolics. Tozo brand which I have used, and a set of Skyreats... yet unopened.

I get the seriousness of controller orientation being critical.

I was in an online discussion the other day, with a Phantom owner much more experienced than myself.

I was questioning why "compass" isn't a part of IOS Litchi, while it is with Android.

He said he always flies long distance parabolic, and uses the Map for orientation. He says it's just as good as compass for orientation.

But I recall another guy awhile back that said he ALWAYS uses compass for orientation... and hadn't used Map in ages.

What gives? Who is right? Of course, I'd like to see IOS Litchi compass for extended waypoints.

Am I wrong to assume Compass is better than Maps, strictly from the orientation issue?

On another note, I was flying a short distance higher altitude test flight the other day. Close to 1000 feet quicky.

I was surprised that I got a signal loss as such close distance, approx 550 feet.

Perhaps I lost signal because of the parabolic, near distance, and high altitude making antenna orientation difficult (unless I was holding the RC over my head? LOL)

Also, an "auto land" suddenly appeared nearly putting her into a tree, tho no such thing was programmed. I always set RTH.

Maybe I hit the HOME button too close to home point forcing the land command, but I thought I had no signal at that point. Maybe it had just re-acquired?

Also, I guess once you have a loss downlink, all subsequent flight data goes unrecorded until signal is back?

if you are within a certain close distance from your homepoint and loose control signal, the bird will attempt to land right where it is, flying in close and high isnt a good idea, and the reflector makes that issue worse.

 

[Mark The Droner]

...

Using a laser pen, I have noticed that the reflectors are not really parabolic! ....

Not sure what you mean by this...

 

[N017RW]

Not sure what you mean by this...

Radio signals/energy are carried by photons.
The parabola has a focal point which is the key to its function.
Using a laser pointer can demonstrate if/where the focal point is relative to the antenna.

 

[Mark The Droner]

He said the reflectors are not parabolic. Are you saying that a parabolic reflector must be mathematically precise? Maybe you're right. Maybe that's why many of us call them windsurfers rather than parabolic.

Seems to me what the OP apparently means is the reflectors are not tuned as he would expect. My understanding is the reflectors are not necessarily supposed to be aimed at a specific focal point for RC because the AC moves around. Hence, you get a wider beam width by spreading the signal somewhat. Seems to me one can design one that way if one wanted but it's not necessarily a design flaw if the signal is allowed to spread a little on an RC system.

 

[N017RW]

I have said before a pie tin will improve signal.
But a cylindrical parabola will focus all incoming waves in a plane and keep all signals IN PHASE.
Phase can be additive or subtractive.

This may explain why some get better results than others.

If one is going to tout a design as parabolic it should be.

 

[Mark The Droner]

Reminds me - I was in emails a while back with this guy here: Ez-12

His antenna is clearly not a mathematically precise parabolic but he still calls it a parabolic reflector. In fact, he says the reflector will work for both 5.8 ghz and 2.4 ghz and it's not even necessary to move the focal point (the X) as some people suggest (his words). I know this is counter intuitive because of the phase shift, but nonetheless, that's what he says.

 

[N017RW]

Reminds me - I was in emails a while back with this guy here: Ez-12

His antenna is clearly not a mathematically precise parabolic but he still calls it a parabolic reflector. In fact, he says the reflector will work for both 5.8 ghz and 2.4 ghz and it's not even necessary to move the focal point (the X) as some people suggest (his words). I know this is counter intuitive because of the phase shift, but nonetheless, that's what he says.

The focal point of a parabola is based on its dimensions.

It is not effected by or a function of EM frequency.

 

[Mark The Droner]

Oh. I thought I was referring to the wavelength differences of the two frequencies as they relate to the distance from the antenna to the reflector.

 

[N017RW]

So did I.
To be clear on my point....
Wavelength or frequency has no function in the focal point of a parabola.

If this was not yours I am not understanding.

 

[Mark The Droner]

I said I didn't understand how the reflector in the link was not a parabolic.

You said a parabolic must have a precise focal point.

I pointed out that the designer of the homemade windsurfer calls his antenna a parabolic when in fact it doesn't have a precise focal point.

Then you brought up the pie tin and added in phase shift.

The conversation went south from there....

 

[N017RW]

I’m sorry if it went south. Having worked in the subject field I was attempting to further explain.

I agree most of the offered designs are not true parabolas.

 

[Bad Andy]

Finally got around to trying out my set of reflectors this past weekend and my range nearly doubled before ET decided to phone home. Didn't stop the RC from telling me signal quality was "poor" right from the get-go. Welcome to NYC, the land of ubiquitous interference.