How to connect antenna base to powder-coated steel?

[Spehro Pefhany]

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.

http://www.bokers.com

 

[Joerg]

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.

http://www.bokers.com

Thanks! It's bookmarked.

They even offer a calendar with scantily clad washers on there

 

[miso]

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.

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.

 

[Joerg]

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:

http://www.gibraltarmailboxes.com/viewproduct.php?id=119&Model=DVKPBZ00&ProductSubType=All+Mailboxes

 

[josephkk]

Gents,

Ran into a wee snag during a design. The metal enclosure is plain steel
that is powder-coated. The guys at the metal shop said that they cannot
provide a nice connection surface for a bulkhead connector like this:

http://www.l-com.com/item.aspx?id=5295

I was hoping they could provide a masked nickel-plated area but ...
nope. They can only provide a threaded stud like those safety ground
ones. Not so cool at several GHz. Ok, we could make a wide shunt strip
for that but that's yet another custom BOM item. Corrosion is also a
major concern here since this gets deployed in coastal regions. So
straight bolting onto bare steel is out.

Anyone know of a clever way to handle this? If someone knows of a
cheaper bulkhead SMA feedthrough connector that would also be nice. Four
bucks is a bit steep.

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.

?-)

 

[Joerg]

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.

 

[josephkk]

I have doubts even about that claim, coming from you.

Shithead, yes. "people", no.

Therein lies the problem, you think everybody is a shithead.

?-)

 

[Joerg]

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

 

[Joerg]

The Geico caveman never used a name in the commercials.

He does, it's always the same: Goicoh