Pointing Antenna(s) at Phantom

[rrmccabe]

Pretty much most of us have tried to explain and refer people with distance issues to how the TX unit radiates the signal. Its not the easiest thing to explain in text.

Tonight I threw together a quick illustration to show someone. Feel free to steal and use it. Comments to improve are welcome.

 

[DBS]

Comments to improve are welcome.

Instructions not clear... stabbed myself in the face with yellow and red arrows :?

 

[rrmccabe]

LOL

 

[unity]

I did EXACTLY as this shows. But I found it hard to take off and land with my thumb sitting right there. Thoughts? Maybe I am using the wrong thumb. Or is that a toe?

 

[flyNfrank]

Very nice and spot on. But you will have to do like someone once said to me, ....that demonstration is only for the stock antennas.

 

[planedr]

My red and yellow arrows are swapped. Will that make it fly upside down?

 

[MapMaker53]

Newbie here.. I understand from this and previous discussions that the antenna should be perpendicular to an invisible line drawn from yourself to the UAV. Using the above photo as reference, this would require a drastic tilt of the RC or repositioning of the antenna if the UAV was at very high altitude overhead. Assuming the perpendicular antenna requirement, I'm wondering why positioning the antenna horizontally (bent to the side 90 degrees like when you store it in a case) wouldn't be the optimal position since it would always be perpendicular to the UAV while you generally face it no matter at what altitude it is in the sky.

 

[rrmccabe]

Newbie here.. I understand from this and previous discussions that the antenna should be perpendicular to an invisible line drawn from yourself to the UAV. Using the above photo as reference, this would require a drastic tilt of the RC or repositioning of the antenna if the UAV was at very high altitude overhead. Assuming the perpendicular antenna requirement, I'm wondering why positioning the antenna horizontally (bent to the side 90 degrees like when you store it in a case) wouldn't be the optimal position since it would always be perpendicular to the UAV while you generally face it no matter at what altitude it is in the sky.

You can move the antenna including the range extender to whatever direction needed to point towards the phantom. Do this by rotating the controller or the antennas themselves. As you said it would require drastic tilt which would be uncomfortable to operate so you will need to do a combination of both at times to get the right orientation.

 

[N017RW]

Newbie here.. I understand from this and previous discussions that the antenna should be perpendicular to an invisible line drawn from yourself to the UAV. Using the above photo as reference, this would require a drastic tilt of the RC or repositioning of the antenna if the UAV was at very high altitude overhead. Assuming the perpendicular antenna requirement, I'm wondering why positioning the antenna horizontally (bent to the side 90 degrees like when you store it in a case) wouldn't be the optimal position since it would always be perpendicular to the UAV while you generally face it no matter at what altitude it is in the sky.

The controller's Tx antenna is polarized along it's length thus when vertical it is vertically polarized.

The top and bottom ends have a null point to them thus there is little propagation from the ends. The best visual is a donut. Picture a donut placed halfway down the antenna as if you were playing 'ring toss'.

The twin diversity Rx antennas on the a/c are positioned on the landing gear... vertically.

By maintaining maximum parallel orientation between the Tx and Rx antennas you achieve the greatest cross section (or overlap if you will) for signal reception thus it is the optimum configuration.

A 90 degree, or perpendicular, orientation produces the least or minimum amount of cross section.

 

[Wally]

Is that a yes...?

 

[rbhamilton]

Is that a yes...?

Not really sure. I think he said you should stab yourself in the face with red arrows...

 

[jadebox]

Newbie here.. I understand from this and previous discussions that the antenna should be perpendicular to an invisible line drawn from yourself to the UAV. Using the above photo as reference, this would require a drastic tilt of the RC or repositioning of the antenna if the UAV was at very high altitude overhead.

Since you usually fly higher when far away, you should angle the antenna so that it points up and towards your head. The angle isn't as important when the 'copter is close to you. So I found (before I switched to a more directional antenna) that angling the antenna so that it points up and towards your head is a good compromise that works most of the time.

If the 'copter is at a high altitude close to you, then you do have to point the entire receiver towards the aircraft to ensure that the antenna is aligned correctly. Even then, you may lose signal because the antennas on the 'copter are at a bad angle. I've found it necessary on occasion to walk away and decrease the angle when the 'copter starts to fly directly over me in order to avoid losing the control signal.

-- Roger

 

[CYeutter]

So if I have this right, it sounds like there are actually two factors to keep in mind,
1. Keep the antenna oriented so it is at right angles to an imaginary line between you and the copter
2. As much as possible, keep the antenna oriented so it is in a parallel plane with the antenna wires in the legs of the copter. Which means generally the antenna on the controller needs to be close to vertical.
If the craft is overhead, keeping both conditions true isn't possible.
Do I have it mostly right?

 

[N017RW]

Sounds like you have the jist of it.

This graphic was what I was trying to describe earlier:

http://www.rcgroups.com/forums/attachme ... id=2087197

 

[rrmccabe]

Because you can can't change the OEM antennas on the bird you can not be ideal in all situations.

From a theoretical standpoint the phantom low and in front of you is as ideal if you can get if you don't include any kind of ground loss.

Good example for me is I know with stock antennas I can fly a lot further horizontally than straight up. When straight up and I am working off the end of the Phantom dipole antenna no matter what I do with the TX antenna.

 

[Stile2112]

Newbie here.. I understand from this and previous discussions that the antenna should be perpendicular to an invisible line drawn from yourself to the UAV. Using the above photo as reference, this would require a drastic tilt of the RC or repositioning of the antenna if the UAV was at very high altitude overhead. Assuming the perpendicular antenna requirement, I'm wondering why positioning the antenna horizontally (bent to the side 90 degrees like when you store it in a case) wouldn't be the optimal position since it would always be perpendicular to the UAV while you generally face it no matter at what altitude it is in the sky.

The best visual is a donut. Picture a donut placed halfway down the antenna as if you were playing 'ring toss'.

Talk about a Pavlovian response..... every time I adjust my transmitter's antenna.... I'm hungry for donuts

 

[rrmccabe]

Well until I upgraded to the FPVLR antennas I used my to store my donuts. It holds 4.

 

[flyNfrank]

Newbie here.. I understand from this and previous discussions that the antenna should be perpendicular to an invisible line drawn from yourself to the UAV. Using the above photo as reference, this would require a drastic tilt of the RC or repositioning of the antenna if the UAV was at very high altitude overhead. Assuming the perpendicular antenna requirement, I'm wondering why positioning the antenna horizontally (bent to the side 90 degrees like when you store it in a case) wouldn't be the optimal position since it would always be perpendicular to the UAV while you generally face it no matter at what altitude it is in the sky.

I do 90% of my flying over head. I nearly lay my antenna down along the top of the controller opposite side of the range extender. 90 degees would be laying it flat on top of controller. In looking at my usual angle it appears to be around 65-70 degrees. When I attempt to brake my height record my antenna is closer to 80 degrees. Brackets keep my antenna from going to the 90 degree angle I would prefer when needing a connection is at it's highest.

When performing a Distance record along the horizon, with holding my controller straight up & down (switches & lever facing the chest) My antenna is also in it's locked straight up & down position. In this case I have to rotate the range extender in the direction of the quad in flight.

The only performance mod I use is the Vision+Utility App. And once I get past 2,000ft I begin paying attention to the connection display in the upper right corner of the screen. I mostly observe the Wifi because it has always seemed to be the most sensitive of the others. This is when you can really see how just the slightest of angle movement is detected on the Wifi connection display.

 

[rrmccabe]

This is when you can really see how just the slightest of angle movement is detected on the Wifi connection display.

Very true. I am in the learning to point and make small corrections phase right now.

Easy to over compensate. Wish there was a S meter on the display.

 

[John Shaw]

Pretty much most of us have tried to explain and refer people with distance issues to how the TX unit radiates the signal. Its not the easiest thing to explain in text.

Tonight I threw together a quick illustration to show someone. Feel free to steal and use it. Comments to improve are welcome.

rrmccabe, I believe your diagram and accompanying explanation (including comments by N017RW ) will provide insight to many. Not many people understand antenna radiation patterns and this understanding can make a big difference on maintaining control of the Phantom.
Those who modify the antennas are obviously on their own and had better understand the benefits and disadvantages of any design they chose to use. I see many antennas presented but seldom enough explanation of their strengths and weaknesses. Typically an antenna that creates a stronger beam in one direction weakens it in all other directions. I expect the designer knows but those that copy may not realize what the downsides are and that can be disasterous.
This is a topic that should be taken seriously.
Thanks