How to connect antenna base to powder-coated steel?

Like I said, you're too much of a goddamned crybaby to perform manufacturing processes efficiently or intelligently, much less know how to. THEN, there is the overt stupidity issue piled on top of that. Sad.

Yeah, and your grasp of covalent and cohesive bonding principles, much lees the materials used is right at NIL, you stupid f*ck.

ANY 5 minute epoxy will NOT adhere to bare steel, and barely 'stays' on painted surfaces. It ages and is generally NOT meant for ANY industrial setting, EVER.

You need industrial grade epoxies at the bare minimum. Like 3M's DP190 or DP460.

Even those are brittle in nature though. The conductive epoxy was suggested because it does what is needed. Yes, most advanced epoxies require thermal cure. Most that do not are not that great at performing under pressure.

You cannot spot weld onto powder coat, and if you do it bare, it gets powder coated afterward. Doh!

Of course it would be done before the powder coat.

Masking, such as precut silicone-adhesive polyimide discs would be applied, and they are rated to easily withstand the typical 200°C curing temperature for the powder coat.

Lots of sources for these things.

I actually thought that bit was too obvious to bother mentioning.

Best regards, Spehro Pefhany

But it should be a NEMA box. Or built to such standards.

You never really get a low inductance connection at GHz frequencies. You are far better off shielding the parts of the PCB that need to be shielded.

A pigtail IS a feedthrough without a connection. You have coax hanging from the box with a connector. Personally I don't like that scheme UNLESS I can open up the box and replace the coax. But it is very common.

Antenna with pigtail:

The box has to be full custom because there's also some big gear and plumbing in there. Unfortunately also controllers in plastic enclosures. But it's quite weather-proof.

Can't. It's a retrofit situation where my stuff has to be installed as an upgrade on thousands of units, and after that new units but they don't want to redesign the controllers. Those are in plastic cases inside so there will be some radiation of RF, potentially messing with our RX function. The noisy stuff will be well shielded.

The inductance does not have to be zero, low enough is good enough :-)

That's a Yagi, that won't need RF-proof grounding. We only have a rubber duck antenna, max allowed per FCC is 2dBi, plus no more space. This needs (somewhat of) a ground plane, else the coax inside would become part of the antenna and pick up stuff.

To me it was obvious :-)

Have asked but no response yet. Looks like lots of bulkhead stuff is (thinly) gold-plated brass these days. Gold is zero on the galvanic table so I hope it'll be ok. The brass would be. Now a big Ni-Au plated washer, that would look really cool. But with gold being at $1654 that probably isn't going to fly.

If you can't find something standard, these guys have or can make just about anything you might want, and prices are not too unreasonable for moderate quantity.

Thanks! It's bookmarked.

They even offer a calendar with scantily clad washers on there :-)

I only showed the antenna to display a pigtail.

So this box is going to be horizontal to act as a ground plane? I don't know. Most places, the rail falls vertically. ;-) Generally a rectangular box outdoors would be as vertical as possible to help it drain. If the box is vertical, it isn't much of a ground plane.

Think of it as a box the size of a really big PC tower. But the top has a lid that can be open to get access to some plumbing and stuff. The lid is slightly slanted so rain will run off. Maybe 10-15 degrees. The antenna is on that lid and it has to be a rubber duck type for regulatory reasons. There must be a released document that says this antenna is less than 2dBi in gain, and we have that document.

Like this, just a lot bigger and a little less slant on the lid:

Is it powder coated both inside and out? Gasket on the outside, bare metal (regalvanized) on the inside, a little grease around the nut on the inside. Should be just fine.

?-)

It's coated on both sides. The problem is that this shop ain't willing to plate, and it ain't my decision :-(

But we'll get it done, if needed with a stud and a custom part.

Therein lies the problem, you think everybody is a s*****ad.

?-)

Put everything in a plastic NEMA box.

Didn't you see him in those Geico commercials?

No, that one has an Australian accent and does not change the name all the time :-)

The Geico caveman never used a name in the commercials.

He does, it's always the same: Goicoh :-)