TCDk is a property which all circuit materials possess and it is how much the Dk of the material will change, with a change in temperature. The default test method for determining TCDk is typically done as a raw-material test and this video gives an outline of how to perform TCDk testing in circuit form. The circuit form testing for TCDk is considered a real-world test as opposed to the raw-material test method, which is typically intended for material characterization. Watch this video from John Coonrod covering this topic.

This is the 2nd video on the topic of SIW and this video is focused on real-world issues which can impact the RF performance of SIW.

This video shows an overview of multiple studies, where many different final plated finishes were evaluated for RF performance at millimeter-wave frequencies.

This video gives more details of the glass weave effect and shows how to quantify the glass weave effect in certain laminates.

This blog will attempt to “see through” the effects of glass on high frequency circuit boards, especially on the millimeter-wave circuits that are becoming so important in emerging automotive radar systems (at 77 GHz) and Fifth Generation (5G) cellular wireless communications systems.

The characteristics of circuit materials have a great deal to do with how well a printed circuit board (PCB) performs, especially at RF/microwave frequencies. Circuit material parameters such as dielectric constant (Dk), dissipation factor (Df), even material thickness can affect the way that different transmission lines, such as microstrip, stripline, and coplanar waveguide, perform in high-frequency circuits. Fortunately, there is a simple and pain-free way to predict how different high-frequency transmission lines will behave when fabricated on different circuit materials: the Microwave Impedance (MWI) Calculator software.

Skin depth is often used to describe the behavior of current flow through circuit conductors, i.e., the copper on a PCB, especially at RF/microwave frequencies. Direct current (DC) may exhibit evenly distributed flow through a conductor such as copper, but high-frequency, sinusoidal current experiences changing energy density as it flows through a PCB’s conductors, with areas of lower and higher current density relative to the surface of the conductor.

As explained in the previous ROG Blog, vehicular radars are already being designed and fabricated at millimeter-wave frequency bands such as 77 GHz. Specifiers of circuit materials for millimeter-wave frequencies (30 to 300 GHz) are faced with special requirements that are often different than those for circuits at microwave frequencies of 30 GHz and below. However, practice and experience of circuit designers working at millimeter-wave frequencies has shown that some circuit material parameters can be tightly linked to achieving high performance in millimeter-wave circuits, and that some circuit materials embody the material parameters as needed for excellent performance at 77 GHz and beyond.