Box apertures and emi

Hi All !

I'm designing the metal box for my project, and now  i am designing the apertures for ventilation on the top cover.

I follow patterns i see out there, and some rules of thumb proposed on several papers.

The pattern i made is two vertical rows of rectangular apertures with the following dimensions:

Aperture dimensions: 1,9mm height 15,1mm length. diagonal: 15.2mm

Distance between columns: 6.4mm and Distance between rows: 4mm

Total rows : 24. The idea with these apertture dimensions is to attenuate somewhat (-20db) at 1ghz...

I just want to know if i am on the right track...despite i think this is a try and fail process... ;D

Jay X

Are you stopping RF getting in or out ?
???

Hi,

Yes, i want to stop Rf to get in...
It is a full analog design with opamps linear supply and transformer output stage. Lundahl. Ll2811.

Db25 connectors, jacks, and xlr male connectors. Also two alps spuj switches....with 10mm round apertures....
A lot of holes....;D

Jay x

Hi,

A new question arise...maybe not much important...

if i place an ac  rocker switch embodied in the front panel, will the aperture be an entry for rfi...?? as the body of the switch is in plastic...

Thank you for your advise!
jay x

JAY X said:

Hi,

A new question arise...maybe not much important...

if i place an ac  rocker switch embodied in the front panel, will the aperture be an entry for rfi...?? as the body of the switch is in plastic...

Thank you for your advise!
jay x

Click to expand...

ANY discontinuity in the enclosure material is a potential entry point for RFI/EMI; you have to live with that. Now the problem with radiated RFI is cell phones. I don't know any analog product that is totally impervious to them, but the remedy is easy. Turn them off!  8)
Actually heavily polluted environments (high-power transmitters, heavy machinery) are also problematic. In all the broadcast installations I know where the final processing equipment is located near the transmitter, the equipment room had to be Faraday'd, because none of the analog equipment (even the most dedicated broadcast stuff) would work properly.
IMO, you can't provide perfect protection; the environment must be controlled.

Hi Abbey!

That is the answer i was waiting for!...

So, when designing we can make all the efforts necessary to to attenuate or stop within a certain limit RFI, but never completely eliminate it. sad but true...

Thanks a lot!
Jay x