High Frequency PCB is a type of PCB used for signal transmission  in the variety of applications including mobile, microwave, radio frequency and high speed design applications.
High Frequency boards come with high frequency laminates are difficult to fabricate because they need to maintain thermal heat transfer of the application, in view of the sensitivity of the signal.
Special materials are used to attain the high frequency given by the High Frequency PCB.
Characteristics of the high frequency board can effect the overall performance of the signal, similarly any change in the Er value of the materials used can widely impact the impedance of the board.
Most of the professionals prefer rogers dielectric material because it turns out to be less expensive, have low DK and DF value, reduced signal loss and appears to be suitable for fabrication and prototyping applications.
Teflon is another common material used in the manufacturing process of the high frequency PCB, which comes with frequency of 5GHz.In terms of DK, DF and water absorption factor, Teflon is the best, but more expensive than FR4.
If your projects requires frequency more than 10GHz with higher quality and stable signal, then Teflon is the best choice.
High frequency signals are vulnerable to noise and come with much tighter impedance tolerance as compared to conventional circuit boards.