Just as an FYI, if you are still having problems with the transmission distance. The wire length for a specific RF frequency affects the signal strength and getting exactly the 1/2 length wire for the specific frequency is a lot stronger than 1/4 or an odd amount. Full length is usually unwieldy, especially getting the appropriate ground plane for it, but it also can increase the signal strength. It does not mean of course that a 1/2 wave is twice as strong as 1/4, but it does increase the power. Here is a simple wire length calculator:
http://www.qsl.net/kd4sai/antencal.html
Another thing to look at is the orientation of both of the antennas affects the distance in a particular direction drastically.
A better bet, is that you can also go with the "real" antenna for under $10.00 plus shipping at the first place I looked (Digikey). And you wont' have to "finagle" anything, a 50 ohm coax cable to a R-SMA connector would allow you to mount your antenna an inch or a couple of feet away from the electronics. The RF module is designed for this, the Antenna pin is flanked on both sides by GND, so you have an excellent point to attach the coax. Since a good dipole has a "virtual" ground plane built in, matched to the antenna, you can get a significant increase I believe. I have used antennas from Linx Technologies a lot in the past, here is a link to the relevant page for their products:
https://www.linxtechnologies.com/en/pro ... l-external
Somewhere on their site they also have the appropriate cables, bare-end coax to R-SMA or there are a couple of choices with cables attached. Digikey carries their antenna and cable assemblies, one 916MHz
I am doing at least half of this from memory, and I probably have gotten some of it wrong, it's been a few years since I had to specify antennas, so I encourage you to do your own research, but I think I haven't steered you completely wrong.
I hope this helps.