Best coaxial cable for Bluerobotics antenna?

General Discussion
1

Hello,

We are building an autonomous underwater vehicle and we want to install a RF antenna so the vehicle can connect to our network when it is floating in the surface. We are working on the antenna enclosure and I wanted to ask what kind of cable would you recommend for the extension of the cellular 4G antenna or the 2.4GHz antenna (we are still not sure which one we will be using for this application). In this case we were also planning to use the newest WetLink Penetrator JPT.

Best regards,

2

Hi @Alex_UJI1 -

Any co-ax cable compatible with the WetLink sizes should work fine (appropriate outside diameter.) However, it is important to note that you’ll need to seal the external termination of the cable where it goes into a type-N connector. In addition, the threaded joint is also not submersible to significant depth, so you’ll want to encapsulate the whole external end! Subsea antennas can be quite challenging… a bunch of effort to only be useful at the surface!

3

So in this case it doesn’t matter if we use a RG-174, RG-316, LMR-200? Our idea was to pass the cable into the containers using the Wetlink penetrators on both ends and then use a crimping tool to install the propper coaxial connector inside the enclosures.

4

Hi @Alex_UJI1 -

That’s correct! Whichever type of co-ax cable you select, just make sure you’re using the appropriately sized WetLink penetrator for that diameter cable. So for a 6.1mm OD cable, you’d use the 6mm HC size. If you’re cable is smaller than the available sizes, heatshrink with internal glue can be used to increase the diameter, this may impact the max depth rating and so you should do some testing to determine the limit - unless your use-case is just at the surface?

Best of luck!

5

One alternative solution, that I have used for a similar application, would be to use a Blue Trail Engineering Simple Penetrator. That system seals to the penetrator with barb fittings on vinyl tubing, leaving a hollow tube for the coax to run through. You would be able to run whatever length needed down the center and cap/seal the far end.

6

Hi @Alex_UJI1, Damon from Blue Trail Engineering here. We also make coax connectors and cables. So you could mold your antenna onto the end of the coax cables and put a coax bulkhead on your vehicle. Then you’d be able to connect and disconnect the antenna in a few seconds.

Damon