Microstrip Resonator Basics and Types

This article delves into the world of microstrip resonators, covering their fundamentals and various types. We’ll explore open-end resonators, stub resonators, ring resonators, and dielectric resonators.

Figure 1 illustrates different kinds of microstrip resonators. As we know, boundary conditions dictate that circuits resonate at specific frequencies.

Open-end resonators and stub resonators exhibit a voltage wave maximum at their open edges. Consequently, resonance occurs for an open-end resonator when the following condition is met:

l = n *(1/2)*λg , where n = 1, 2, 3…

For an open stub resonator, resonance is achieved when:

l = n *(1/4) * λg , where n = 1, 2, 3…

For a ring resonator, the condition for resonance is:

2 * π * r = n * λg , where n = 1, 2, 3…

The resonant frequencies can be determined using the following equation:

$λg = λ0 / (εeff)0.5 = c / (f \* (εeff)0.5)$

One key application of resonators is in the design of filters.

There are four primary types of filters:

• LPF (Low Pass Filter)
• HPF (High Pass Filter)
• BPF (Band Pass Filter)
• BSF (Band Stop Filter)