Microwave Materials

Microwave materials have advanced to a new level over the past 10 to 15 years. Many years ago, only one material was available to RF and microwave designers. That material was a woven Teflon fiberglass material that came in only one thickness, and was used for every application, regardless of the frequency ranges, power levels, or loss requirements that were called out. Today, there are many types of materials with a variety of parameters, so materials can be custom fitted to just about any application. With a variety of materials available, there is no excuse for using the same material for every application.

Woven Teflon Material

No one should rely on a pet material for all designs. The mind-set “We’ve always used this material, why not use it again?” or “This material worked great for our last job, so we might as well use it again; why take chances?” does not work today. There is no excuse for not having a working circuit, provided that the right design procedures are used, if the time is spent choosing the proper material for the application at hand.

Nonwoven Teflon Material

Microwave materials are special types of materials. These materials are an integral part of the circuits they support, not like the low-frequency and digital circuit boards (those with low data rates), where the only functions are to support components and get current from one point to another. The microwave material is actually a part of the circuit that is being designed. This was shown when we distinguished between lumped and distributed components. Also, that microstrip and stripline transmission lines are constructed on a circuit board material and that the required lengths and widths of the transmission lines are determined by the characteristics of the material on which they are placed. So you can see that microwave circuit boards are not ordinary in any respect and that they do much more than support components. The circuit board material is an integral part of the RF and microwave’s circuits for which they are the base. A common thought in the field of RF and microwaves that designers should spend almost as much time choosing a material to use as they do to design the final circuit. That is how important the material is in these high-frequency circuits.