Clamp or Compression type PL-259/ UHF Connector for RG-213 Cable in Right angle termination ,
Install it properly and have a waterproof connection with suitable silicone tube compression inside
Right Angled Connector will reduce strain on the Equipment connector and Provides a stable connection with thick Co-axial Cables.
Above video shows for N-Type connector, Can be adapted for PL-259 or UHF Connector as well
Video Credits : BKL Electronics