Multiple Module Antenna Switch

Hello everyone, I just recently decided to buy a Devo 7e from banggoods, so I decided to join and ask some questions. Seeing it might take around a month to get here.. I was planning out the mods I would do to it. I'm planning on installing two modules in the transmitter, the A7105, and the NFR24L01. Amazon actually has the transmitter for $2 more but with prime, but I wanted to get modules for my v911, and later a v977.

I was wondering since the Devo 7e has spaces for extra switches, could they be used to route each modules antenna to the main external antenna? I want to leave my transmitter looking as close to stock as possible. So my plan was to connect the antenna to two 3-pos switches and wire them up in a way that depending on their positions it would only connect one of the modules to the antenna for the best signal.

I just wanted to know if you guys think this is possible. Now that I think about it there would also be the problem of not having antennas connected and then frying the modules, and the main board.

Very bad idea.
HF leak on the active module, no termination on the inactive. ...
You will damage the PA.

Are you trying to preserve the looks while you are using it, or the ability to go back to the original looks later?

If the latter, then you can set up an external rig to replace the current antenna structure with one to hold all three antennas in appropriate positions. Putting all three of them in the existing structure doesn't seem like a good idea, as having even passive antennas that close to a radiating antenna could interfere with it.

That's why if you're doing the former, just set up the extra antennas inside the case. The active part is the last 31mm's (quarter wave) that aren't shielded. Try and get that bit as far away from the hardware as possible, and preferably at right angles to where your rx's will be.

I have tried to solve this issue two different ways, and I am interested in opinions.

first is a D7e where I have an antenna mount for every module. I use a dummy load non-radiating terminator on the module antenna not being used, and move the antenna to the active module.

second is a D7e where I wanted to not have an antenna farm sticking out the top, and i have arranged the antennas cross-ways in the top of the radio , just above the switches, two in the front half, and two in the back.

I realize the first setup will get better range than the second, but so far flying off the CYRF and NRF modules I get range as far as I can see, which is all I need.

Yeah, I'm trying to preserve the look of the transmitter, I don't want to have multiple antennas sticking out of it. I guess I will have to set up the antennas within the module. I'm just a little scared of the A7105 module since I bought the shielded one from banggood it i read that it does not get very good range, not even close to the rated 500ft. I wont be flying that far but it would be better to have a farther range to ensure good reception to the Rx.

@skretchmer Interesting, would it be possible to wire each antenna to individual dummy loads and then creating a switch that routes the transmission to the main antenna with switches? This is sounding more like an electrical project. haha

If you absolutely want to have just one antenna, wait for the Single-Board Universal Module to be released. All RF transceivers on the board will share the same antenna.

Stuff all the antennas into the existing external tube. (Or get a bigger one if you're using longer antennas.)

Range test each one. I'm betting you'll have very good results.

I only have two antennas in my 7e, so far, but it doesn't seem to effect performance at all.

The antenna farm and/or fancy switching seem unnecessary.

Edit: The only way to justify an antenna farm is if you're planning to transmit on more than one at a time. Or you're covering different frequency bands.

IIUC, having even passive antennas that close to the active antenna can create problems. I'm not a EE, so maybe someone who actually groks the math involved can provide accurate information.

Because of that, I either go with an antenna farm (on my 10, as that simply looks cool) or leave the antenna's inside the case (on my 6s). Never had range problems on either one.