@SrRochardBunson @ClaraListensprechen@universeodon.com @Ralph058 @sergio_101 Yes. Mica (the mineral, but carefully selected sheets of it) has been used for like 100 years to make capacitors. No capacitor dielectric can equal its performance, yet.
These fabulous characteristics of mica used to be very important in the design and manufacture of "analog" radios. Their importance is far less today for two main reasons. Modern radio designs don't depend on capacitor performance to maintain frequency stability. 1) We use digital methods to produce extremely precise frequencies locked to a quartz crystal reference. 2) Transmitters are solid state and run on low voltages so the high voltage capability of mica is unimportant. You can use any old material for coupling caps.
Mica still shines in certain niche applications like high powered radio transmitters like 250 kW and 500 kW shortwave transmitters. Those still use vacuum tubes that are supplied with 10,000 to 15,000 volts at 10, 20, 30 amps. Here you'll find mica caps. Some are the size of a basketball and weigh 25 pounds.
@SrRochardBunson @ClaraListensprechen@universeodon.com @Ralph058 @sergio_101 In discussing mica I simply said "RF". What do I mean by that? What I mean is something called dielectric loss. Dielectrics are not perfect. Some are terrible but you can still use them in certain applications.
Mica has no dielectric soaking effect and extremely low dielectric loss. This matters a lot in a high powered transmitter like I mentioned. Try pushing 500,000 watts of RF power through anything but a mica capacitor of similar size and volume and it will simply vaporize or explode. But a mica cap will just cruise along for years doing this 24/7. And when the transmitter is decommissioned you can pick the capacitor up, install it in a new transmitter and do it again.
