900mhz dipole antenna placement carbon fuselage

[cptsnoopy]

Will putting only the inner wire of a 900mhz receiver dipole antenna outside a carbon fuselage and leaving the shield wire half of the antenna inside the carbon fuselage degrade the receiving ability of the antenna?
The idea of placing the antenna in this fashion seems counterintuitive to me and I would have never tried it but there is someone advocating that only the inner element of the dipole needs to be sticking outside the carbon skin of the fuselage. If someone has already done testing to see what effect this might have on range I would love to hear about it so I won’t simply be repeating the testing all over again.

 

[HENNY]

Will putting only the inner wire of a 900mhz receiver dipole antenna outside a carbon fuselage and leaving the shield wire half of the antenna inside the carbon fuselage degrade the receiving ability of the antenna?
The idea of placing the antenna in this fashion seems counterintuitive to me and I would have never tried it but there is someone advocating that only the inner element of the dipole needs to be sticking outside the carbon skin of the fuselage. If someone has already done testing to see what effect this might have on range I would love to hear about it so I won’t simply be repeating the testing all over again.

The 900mhz dipole is a complete antenna which needs to be all outside the carbon fuselage and spaced away from the fuselage, and not taped to it. Sounds like you may have cut the dipole portion off the antenna, which will not be correct.

 

[cptsnoopy]

Thank you Henry,
I have mounted my antenna as you see in the pictures. It’s by no means the optimal position for maximum range but it is a compromise that has been working for me.
It is someone else who represents a well known supplier for soaring enthusiasts that is advocating only placing one half of the dipole receiver antenna outside the fuselage. I found that advice to be absurd but wanted to get input from knowledgeable folks before I challenge this advice.

 

[HENNY]

Thank you Henry,
I have mounted my antenna as you see in the pictures. It’s by no means the optimal position for maximum range but it is a compromise that has been working for me.
It is someone else who represents a well known supplier for soaring enthusiasts that is advocating only placing one half of the dipole receiver antenna outside the fuselage. I found that advice to be absurd but wanted to get input from knowledgeable folks before I challenge this advice.

My name is Henny, not Henry. Is that a carbon fiber tube you have taped the antenna to. Is that the antenna that came with the receiver, it looks more like a 2.4g antenna. Which receiver are you using. The antenna is the whole section forming a Tee. The shield is an active part of the Tee section antenna. I would space it at least 1 to 2 inches off the tube. Carbon fiber affects the resonant frequency of any antenna so having it near the carbon will reduce range. In the FRsky radio's you can also adjust 900mhz output power. Have you researched this.

 

[Landru]

I think Henny got it right. The whole antenna should be outside the carbon fuselage and at least an inch or two away for reliable performance. I'd be very concerned about shading with the setup shown. Personally, I wouldn't use it.

Beyond that, a single antenna placed horizontally will suffer from cross-polarization in use. For that reason, I believe that vertical polarization on both the transmitter and receiver antennas is the preferred setup.

If the setup has already been flown, the RSSI and link quality telemetry data will give a good idea of its effectiveness.

Below is a 900MHz antenna setup I flew with for quite a while. There was no other antenna or receiver in the model. Reception was good except directly overhead (due to nulling). Model was flown to distances of up to 1km.

 

[cptsnoopy]

Hi Henny,
Sorry about that misspelling.
Yes, the fuselage is a tapered carbon tube.
Yes, the antenna came with the R9 Mini receiver.
My install is a compromise and I would love to have it further away from the fuselage but that would not be practical. As long as the system works line of sight that is enough for my purposes.
I do not have RSSI or signal strength available as I use an R9M module in a Multiplex EVO transmitter. I have my module set to use a power setting it chooses.
Great setup Landru but not practical for the F5J performance needed to be competitive.
Now that we’ve covered what I’m using, let’s take a look at why I posted.
There is an individual asserting that only the inner one half of a dipole receiver antenna need be outside outside a carbon fuselage to work well enough for line of sight purposes. I believe this assertion to be incorrect and your responses to me concerning my install leads me to believe that you both agree. I appreciate your time gentlemen.

 

[cptsnoopy]

More information. A gentleman from Finland responded that if 1/2 of the 1/2 wave dipole is removed you end up with a 1/4 wave monopole. Seems logical. Not as good as the dipole but quite possibly more practical.

 

[HENNY]

More information. A gentleman from Finland responded that if 1/2 of the 1/2 wave dipole is removed you end up with a 1/4 wave monopole. Seems logical. Not as good as the dipole but quite possibly more practical.

And you are still wondering why your range is so limited.