Accurate Circuit Model of Open Resonator System for Dielectric Material Characterization

Planar Fabry–Perot directive antenna: a simplified analysis by equivalent circuit approach

“…Following what developed in [9][10][11], the coupling between the field inside the cavity, Equations (23) and (24), and the field into a rectangular metallic waveguide, assumed as cavity feed, is matched on the coupling aperture, thus allowing an equivalent circuit representation where only one cavity resonant mode is taken into account, while all T E n0 modes of the exciting waveguide are considered. Under the above hypotheses, the equivalent circuit modeling both the cavity behavior and the cavity-to-waveguide coupling is derived ( Figure 3).…”

Microwave Open Resonator Techniques – Part II: Applications

“…At this purpose, the approach proposed in [5] is adopted, which is based on a complete eigenfunctions analysis leading to the equivalent circuit of Fig. 2 [8].…”

“…2 From the circuit reported in Fig. 2 it is easy to derive the expressions of the waveguide input impedance Z i and the reflection coefficient Γ, respectively given as [8]:…”

“…1) and unknown complex permittivity ǫ = ǫ ′ − jǫ ′′ . Under this hypothesis, the equivalent impedance Z S can be easily expressed as [8]:…”

“…After some manipulations, the real and imaginary parts of impedance Z S can be derived as follows [8]:…”