A novel way for testing z-direction permittivity by TM_0n0 mode cylinder cavity

A novel way to measure the permittivity of substrate in the Z direction has been proposed in this document. Compared with the traditional stripline resonant method, this method is simpler to operate with the help of TM mode cylindrical cavity and ensures accuracy with the help of mode match method. To demonstrate the feasibility of this method, a verity experiment with simulation and measurement has been shown in this document. As a result, the calculation results can well match the simulation results. However, the current line cut cannot be solved perfectly in the actual test, which makes the tangent of the loss angle increase the error a lot.