LRAUV_ANTENNA_REV_C

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15 Oct 2024

From ETR:

We need to make new antennas for the LRAUV because we have a lot of failed ones that need replacing. However, we have identified a few minor issues with the board design that we want to fix.
The original design files for the antenna are here:
smb://atlas.shore.mbari.org/projectlibrary/901727.99_LRAUV5_Build/DesignDrawings/EE_Drawings/LRAUVWiring/AntennaSystem/100221187rB_LRAUV-DUAL-UWB-ANTENNA

It might make sense to just copy that directory and make a rev C so we keep that old directory untouched. Alternatively we could migrate this into the vault but we can do that after the fact.

The first change is the outline. We want to have urethane running around the whole antenna so we need more board space around the active parts. Brett generated a DXF file with the intended new outline which I attached. Let me know if you have issues getting that into Orcad. The dimensions don't have to be exact, it just gives an idea of how much the outline should move out. There should not be any change to the copper.

The second change is related to the coax entry points at the bottom. The old board was designed for a very thin coax cable which would fit into the gap where the outer metal jacket would get soldered to the ground pads and the core to the pin in front. We are planning to use a different coax cable now called 1601 (https://insulatedwire.com/wp-content/uploads/2024/04/IW-160-Series-low-loss-coaxial-cable.pdf). This requires the gap to be around 0.17inches (the metal braid is around 0.16 but we want to leave some space so the braid can get tinned). I'd assume it's just a footprint change for the connector symbol. I would keep the ground area around it the same, just widen the gap and adjust the solder mask accordingly.

The board is made with a fancy RF ceramic instead of normal fiberglass board, called Rogers 4003C. I attached a quote from before to this email as reference. It might be worth going with Circuits West again since they have done it before. It's all called out in the manufacturing drawing in the project library but it might be worth re-iterating when having them manufacture the board.