Re: cap dielectric constant (K) of mylar

Subject:      Re: cap dielectric constant (K) of mylar
       Date:  Thu, 17 Apr 1997 20:10:23 -0700
       From:  BertHickman <bert.hickman-at-aquila-dot-com>
Organization: Stoneridge Engineering
         To:  Tesla List <tesla-at-pupman-dot-com>

> Does anyone have data on the dielectric constant of
> mylar? I found some at a very nice price...and it seems
> tougher than the polyethlene sheet..thought of using
> it for the caps we're building...
> thanks, appreciate comments..
> Chris Dunagan


Mylar has a k of about 4. However, its dissipation factor (it's
"lossiness" when used in an AC application) is 100-200 times that of
LDPE (0.02 versus 0.00008 to 0.00015). While you can make a cap out of
this material, it won't perform nearly as well as LDPE, since a
significant portion of your primary energy will be expended heating up
your mylar dielectric. If it's cheap enough, you could give it a try!
But remember, LDPE (low density polyethylene) is also VERY

Safe coilin to you!

-- Bert --