Path: ...!Xl.tags.giganews.com!local-4.nntp.ord.giganews.com!news.giganews.com.POSTED!not-for-mail NNTP-Posting-Date: Wed, 27 Nov 2024 18:37:26 +0000 From: Joe Gwinn Newsgroups: sci.electronics.design Subject: Re: Mirror as ground plane Date: Wed, 27 Nov 2024 13:37:01 -0500 Message-ID: References: User-Agent: ForteAgent/8.00.32.1272 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 51 X-Usenet-Provider: http://www.giganews.com X-Trace: sv3-CU1qojBTZai+t7JVYSOmsM4VsPnhEpovkSyMEKOd/Icpeo+9nrrbRdtzdNZbbcSdxp7P7iAckmQa3mB!oGg+7B1SfZgw9AQ/wYWoE4gS1X4mCKFca0GPkXSjqO6Q1UYxU7k0FUDMQ+4AG8KupYkaNXA= X-Complaints-To: abuse@giganews.com X-DMCA-Notifications: http://www.giganews.com/info/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 2894 On Wed, 27 Nov 2024 17:08:04 +0000, John R Walliker wrote: >On 27/11/2024 16:41, Joe Gwinn wrote: >> On Wed, 27 Nov 2024 14:24:20 -0000 (UTC), Phil Hobbs >> wrote: >> >>> legg wrote: >>>> >>>> Anyone had experience using metalization on glass (mirror) >>>> as a ground plane or shield? >>>> >>>> Any data on conductivity etc? >>>> >>>> RL >>>> >>> >>> The best quality second-surface mirrors are coated with silver, followed by >>> copper plating and a coat of paint. Those should be pretty good if you can >>> get wires on them. >> >> A classic way to connect to such things is conductive silver epoxy, >> probably to silver-plated copper wire. Not tin-plated for long-term >> use. >> >> . >> >> As for shielding effectiveness, the key question is the resistance of >> a square of the coating, connected only on opposite parallel sides. >> >> >>> Poorer ones have aluminum coatings around 2-3 nm thick and no plating. >> >> Probably won't work, between high square resistance and oxide layer >> preventing reliable connection. >> >> Though people do use metallized Mylar film, with a long bare tinned >> copper ground wire in direct contact with the aluminum side, and in a >> cable this does work. >> >> Joe Gwinn >At high enough frequencies there is no need for direct connection. >Adhesive copper tape stuck to the varnish film on the back of an >ordinary mirror may provide enough capacitive coupling to make a >good connection. It all depends on the proposed application, which >we don't know. >John Agreed, Joe