Reciprocity-Based IMPM: An Innovative and Efficient Method for Electromagnetic Design Focusing on Antenna Impedance and Radiation Characteristics

In this study, we introduce a novel internal multiport method (IMPM) based on the reciprocity theorem, termed reciprocity-based IMPM (R-IMPM), for electromagnetic (EM) designs that address both antenna impedance and radiation performance. Using R-IMPM, the designed radiator is analyzed as if subjected to radiation from a far-field Hertzian dipole, facilitating precise calculations of its far-field radiation characteristics. A rigorous design methodology is developed and validated through two illustrative examples, demonstrating that both single and multiport antennas achieve impedance matching with |<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub>| ≤ −10 dB, efficiency exceeding 70%, and great filtering characteristics. Specifically, high isolation with |<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub>| ≤ −20 dB is achieved for the two-port filtering antenna. Moreover, results obtained using R-IMPM align with EM simulation outcomes. Measured results, including S-parameters, efficiency, and realized gain, further substantiate the accuracy of R-IMPM. Comparative runtime analyses reveal that R-IMPM achieves a ten-fold acceleration in calculation speed compared to conventional IMPM.