Cavity Filters: High Performance Under High Power

As discussed in previous blog posts, resonators are the building blocks used to create filters. Recently, we published a blog post that discussed two different types of resonators – coaxial ceramic and dielectric. In this post, we will cover the details of a third type of resonator – the cavity resonator.

At a high level, a cavity resonator is designed so that a space, or cavity, is enclosed by a metallic conducting surface, like a metal box. Inside the metal box, the electromagnetic waves reflect between the cavity walls. Standing waves are formed at particular frequencies and the cavity resonates at frequencies determined by the size and construction of the cavity. Conductors inserted into the cavity, as shown in Figure 1, allow for energy to be coupled into or out of the cavity.