In the image below is our recommended L1/L2 GPS/GLONASS antenna for general purpose RTK work as well as some useful items to mount it. Click on it twice if you want an extreme high res image.
The device shown here is an Antcom 53GO1216A4-XS-1 antenna. You can read more about why we recommend it here. At the bottom center is the top side view, while at the right it is inverted so you can see the connection point and the SMA plug (other plug types available). A metal ground plane ring (removable) is also shown. This is an L1/L2 device, but a similar L1-only one is also available.
Also shown are two common ways to mount the antenna, both using 3-inch stand-offs on a standard 5/8 inch 11 threads per inch mounting. You will need the standoff for your coax plug to clear the antenna, even with a 90 degree coax fitting, we find this to be true.
At the the rear right is a common vehicle magnetic mount (SECO PN#5114-050). Hint: If you are placing this on a vehicle whose paint you value, we suggest you cover the bottom with duct tape. Better yet, go to your local village sign maker and get a small piece of magnetic sheet material, and place that on the vehicle (wax first and then never move it again), then place the antenna mag-mount on top of that.
At the left side and to the rear is a common tribrach, a device used with a survey tripod to ensure a level placement. Hint: Note that this one uses an optical laser for the plumb bob. The red button turns it on and off. You will find a traditional hanging weight style plumb bob to be completely useless along a roadway due to vehicular drafts. Similarity, an optical viewing one is hard to use when the tripod has been set above eye level (often done with GNSS work to keep the antenna above the people). So we would strongly recommend you consider a tribrach with a laser attachment if you will be doing this sort of work very often.
Both of these adapters are widely available from suppliers to the survey community.
We purchase these sort of materials from Stakemill