Guidance or resonance conditions for strips or disks embedded in homogeneous and layered media

The authors illustrate how the guidance or resonance conditions of strips or disks embedded in layered media can be formulated easily using a new notation. It is shown that, once the reflection operator of a reflecting medium is known, one can also find the guidance or resonance condition of this structure quite easily. Guidance or resonance conditions can also be found when the reflecting medium is interacting with another strip or disk. This is illustrated with the calculations of the guidance of a microstrip line with an infinite ground plane and with a finite ground plane. The results for the infinite ground plane case agree very well with previous calculations on these problems, while the results for the finite ground plane case are new