Transmission line modeling (TLM) for evaluation of absorption in ferrite based multi layer microwave absorber

The Intersection of Computational Design and Wearable‐Optimized Electrospun Structural Nanohybrids for Electromagnetic Absorption

“…Accordingly, each layer acts as an impedance element (𝜂 i denotes the intrinsic impedance of the i-th layer) and the impedance of the wave travelling in free space is considered as the output impedance (Z out ), as illustrated in Figure 2A. [22,29] Since the wave impedance approaches the intrinsic impedance of the homogeneous medium that the wave propagates through, in the case of free space…”

“…and 𝜖 0 ≈8.85 × 10 −12 F m −1 are the intrinsic impedance, permeability, and permittivity of free space, respectively). [30] Therefore, R is proportional to the mismatch between Z out and the input impedance (Z in ) (i.e., the opposition to current flow in the transmission line) as: [29,31,32]…”

“…Accordingly, each layer acts as an impedance element (η i denotes the intrinsic impedance of the i ‐th layer) and the impedance of the wave travelling in free space is considered as the output impedance ( Z out ), as illustrated in Figure A. [ 22,29 ] Since the wave impedance approaches the intrinsic impedance of the homogeneous medium that the wave propagates through, in the case of free space Z out = Z 0 = η 0 = $$\sqrt {{\mu }_0/{\varepsilon }_0} $$ = 377 Ω ( Z 0 , μ 0 = 4 π × 10 −7 H m −1 , and ε 0 ≈8.85 × 10 −12 F m −1 are the intrinsic impedance, permeability, and permittivity of free space, respectively). [ 30 ] Therefore, R is proportional to the mismatch between Z out and the input impedance ( Z in ) (i.e., the opposition to current flow in the transmission line) as: [ 29,31,32 ] $$$$\begin{equation}R\ = {{{\Gamma}}}^2\ = \left( {\frac{{{Z}_{in} - {Z}_{out}}}{{{Z}_{in} + {Z}_{out}}}} \right){\ }^2\end{equation}$$$$where Γ is the reflection coefficient.…”

“…[ 22,29 ] Since the wave impedance approaches the intrinsic impedance of the homogeneous medium that the wave propagates through, in the case of free space Z out = Z 0 = η 0 = $$\sqrt {{\mu }_0/{\varepsilon }_0} $$ = 377 Ω ( Z 0 , μ 0 = 4 π × 10 −7 H m −1 , and ε 0 ≈8.85 × 10 −12 F m −1 are the intrinsic impedance, permeability, and permittivity of free space, respectively). [ 30 ] Therefore, R is proportional to the mismatch between Z out and the input impedance ( Z in ) (i.e., the opposition to current flow in the transmission line) as: [ 29,31,32 ] $$$$\begin{equation}R\ = {{{\Gamma}}}^2\ = \left( {\frac{{{Z}_{in} - {Z}_{out}}}{{{Z}_{in} + {Z}_{out}}}} \right){\ }^2\end{equation}$$$$where Γ is the reflection coefficient. Z in at the front surface of the assumed transmission line composed of i impedance elements can be calculated as: $$$$\begin{equation}{Z}_i = {\eta }_i\ \frac{{{Z}_{i - 1} + {\eta }_i\tanh \left( {{\gamma }_{i} \ell_{i}} \right)}}{{{\eta }_i + {Z}_{i - 1}\tanh \left( {{\gamma }_{i} \ell_{i}} \right)}}\end{equation}$$$$…”

Estimation of Reflectivity and Shielding Effectiveness of Three Layered Laminate Electromagnetic Shield at X-Band

“…Various types of electromagnetic shields like single [2,13] and multi layered conductors [2][3][4], conductive polymers [13][14][15][16][17] sandwiched between conductive layers, etc. are reported in the open literature whose design concentrates on optimizing performance on shielding effectiveness.…”