Correct way to set up PCB receiver aerials?

[Pilot Ben 28]

I've seen the 3D printed rigs for them, which hold them both at 45 degrees, in a sort of V shape arrangement. I've now ended up with 3 PCB aerial type units, two of which were installed in the models and had the aerials setup the same way you would rig up normal aerials, hence why I am confused about the "correct" way of setting them up. I also wondered what the actual difference between PCB and normal is? I have previously opened them up and found them to be the same, bar a cheeseboard shaped lump of PCB on one receiver, so I am wondering why the set-up is different than normal?

Thank you  

B  

[Bravedan 106]

Aerials on 2.4GHz should ideally be at 90 degrees between the two. The aerial is only the short usually silver part at the end, the rest is just co-ax.

The problem with PCB aerials (I call them "door wedge" type) is that "edge on" the aerial thickness is the depth of the track, i.e. not a lot! If in flight the edge of both aerials is facing the Tx then signal strength does suffer, and while usually nowhere near problem levels, its not the BEST possible.

The CORRECT orientation for PCB aerials is therefore so the LENGTH of the two aerials is 90, BUT ALSO that the PCB faces are at 90, so whichever way you look at them one broad face is towards the Tx (roughly).

Before someone challenges this as worth doing, they should remember/bear in mind I spent six months working with FrSky improving the Horus 12S and that included RF/IXJT performance measurement and tuning.

Have to say after lots of use I personally do not like the door wedge type, too large and intrusive in many models and so I usually buy wire type or change them for wire type, though the dB recorded from using them if set up well is OK. 

They are quite OK if space allows, but lets face it, if visible they are damn ugly!!!

 

[Pilot Ben 28]

Cheers Dave. Hmmm well, I do have some spare aerials, so I guess I'll stick them on instead.... The model is a nice Spitfire, and whilst it isn't small, there is a lot of wiring so I'd rather a super clean setup.

 

Thanks very much @Bravedan :D 

[Gerard 10]

On my way to returning to flying and amongst the renovation / maintenance items bought, I have purchased two FrSky X8R receivers for future use.  I also bought the specific standard whip antennas to replace the pcb ones.  Very easy to open the receiver and replacement of the antennas looks straight forward.

[Pilot Ben 28]

9 minutes ago, Gerard said:

On my way to returning to flying and amongst the renovation / maintenance items bought, I have purchased two FrSky X8R receivers for future use.  I also bought the specific standard whip antennas to replace the pcb ones.  Very easy to open the receiver and replacement of the antennas looks straight forward.

Just make sure to secure the aerials again! You’ll have seen the yellowish glue that holds them down from the factory, but I find a drop of hot glue works a treat too...

 

B  

[Gerard 10]

Thanks Ben,

I was thinking hot glue might be the way to go so I will do this when I get to the change of antenna.

[Bravedan 106]

Gerard and I discussed this, but for wider reading.

The material FrSky use is a silicone sealer electrical product, designed to be high resistance and fully moisture resistant.  While Hot Glue may do the job, its electrical properties are harder to be certain of, especially its conductivity in damp conditions. It might also make removal difficult.

I have used Aquarium Silicone successfully (as its easy to get hold of), and at least its water resistance is ensured!!

However, the CORRECT stuff is:-

https://uk.rs-online.com/web/p/silicone-sealants/0555588/

 

[Gerard 10]

Thanks Dave.  I will follow up on that.