Comparison of Bowtie Slot and Rectangular Waveguide-Based Antennas for Microwave Medical Imaging

Abstract

In this work, two radiating elements were selected as a suitable candidates for use in the new generation of microwave imaging system developed at ELEDIA@CTU in Prague. These elements are the antenna based on the rectangular waveguide section and the bowtie slot antenna. Both elements meet the criteria we have established based on experience with the previous system: dominant radiation in the imaged domain, radiation symmetry and no need for a balun. The work deals with the verification of the fulfillment of the desired antenna properties and the mutual comparison of the two antenna elements by means of numerical simulations. Although both antenna elements exhibit the desired properties, the bowtie slot antenna exhibits lower internal losses compared to the rectangular waveguide-based antenna. This increases the magnitude of the transmission coefficients in our microwave imaging system by about 13 dB to about −74 dB (for the most distant antennas of the system) for the bowtie slot antenna (in comparison to the rectangular waveguide-based antenna). In addition, it can be expected that for this antenna element it will be easier to guarantee the reproducebility of the production and thus reduce the differences of the individual antenna elements in the antenna array of the microwave imaging system.