A Dimension Estimation Method for Rigid and Flexible Planar Antennas Based on Characteristic Mode Analysis

Abstract

An empirical method for simplified dimension estimation of patch antennas is proposed in this work based on characteristic mode analysis (CMA). This method involves generating formulae to calculate substrate-independent antenna patch widths produced from the antenna’s characteristic angle. This enables the definition of a relationship between the characteristic angle and the natural resonant frequency of an antenna structure, bridging the changes of resonant frequencies contributed by possible variation in substrate properties. From here, the end ‘calibrated’ results can be used to generate specific formulae for each antenna to determine the width of the patch at different operating frequencies, making it time- and resource-efficient. This method was validated using conventional and slotted antennas designed using different substrates, both rigid (RO4003C, Rogers RT/Duroid 5880) and conventional (felt, denim fabric). Measurement results obtained were in satisfactory agreement with simulated results, even without considering the substrates and excitations. Finally, this method was also applied in designing dual-band antennas using flexible materials for wearable applications, indicating good agreement with experimental results.