UHF RFID Tag Antenna-Based Sensing for Corrosion Detection & Characterization Using Principal Component Analysis

Abstract

The authors identified errors in [1, eq. (1)] , which states \begin{align*} P_{R\leftarrow T}[\Psi (\theta,\phi)]=\frac {1}{4\pi }& \left({\frac {\lambda _{0}}{4\pi d}}\right)^{2} & \times \,P_{in}G_{R}^{2}(\theta,\phi)\eta ^{2}_{p}RCS[\Psi (\theta,\phi)].\end{align*} Knowing that the dimensions of $P_{R\leftarrow T}$ function, $\lambda _{0}$ , $ P_{\mathrm {in}}, ~d$ , and RCS function are watt, meter, watt, meter, and square meter, respectively, also $\eta _{p}$ and $G_{R}$ functions do not have any dimension—it is seen that both sides of [1, eq. (1)] are not in the same dimension. Looking at another reference, [2, eq. (3)] , it is seen that the mathematical power of $d$ is equal to 2 \begin{align*} P_{R\leftarrow T}[\Psi (\theta,\phi)]=\frac {1}{4\pi }& \left({\frac {\lambda _{0}}{4\pi d^{2}}}\right)^{2} \\[-1pt]&\times \,P_{in}G_{R}^{2}(\theta,\phi)\eta ^{2}_{p}RCS[\Psi (\theta,\phi)]\end{align*} and the mathematical power of $d$ is not 1 as given in [1, eq. (1)] . However, the rest of the paper and analysis given in [1] are still correct.