Hello looking for some assistance in increasing my range with the Sparkfun RTK Surveyor and I currently have a set of 915MHz, 500mW antennas. Would a set of antennas with a higher DBI increase my range or would I also need a larger power supply?
Thanks
You might try both 
Usually we have these https://www.sparkfun.com/products/17255 available, but they’re sold out right now :-/ You could probably find something similar elsewhere, though
Using big ol’ antennae helps a lot https://www.sparkfun.com/products/15597 can go over a mile with line-of-sight 