Thickness of FR-4 substrate

Hello,
I work with patch antenna at 33 GHz, it is possible to use a thickness= 7.04 for FR-4 substrate or it is so much?
Thank you in advance.

FR4 is very lossy (high loss tangent), your antenna will be very inefficient with FR4.

Very bad idea. Also, in addition to the loss tangent, the dielectric constant isn't that well controlled by the manufacturer. Look into using one of Roger's substrates, or even a custom alumina substrate.

Bad idea.

1. u could not get the exact valune of the dielectric constant of FR4 at 33GHz.

2. At 33GHz, loss tangent of FR4 is very large.