Design of a wideband Balun for Archimedean spiral antenna in energy harvesting

Abstract

This paper presents the design of a wideband Balun for Archimedean spiral antenna. The Balun is designed with a microstrip Line (MSL) to parallel stripline (PSL) transition which is used as a balanced feed for Archimedean spiral antenna. This transition Balun has the wideband performance of 194% over the band of 0.5GHz to 18.5 GHz. The back-to-back MSL to PSL has a return loss of better than 15dB over the band of operation. The performance of the Balun was validated with the spiral antenna. The measured results were compared with the simulated results and it shows that the Balun operates well over wideband frequency range. The Balun is designed and fabricated using the commonly available FR4 substrate with permittivity of 4.2. The designs have been simulated and optimized using 3D Electromagnetic Solver CST Microwave Studio.

Radiating a circularly polarized impulse through a dispersive spiral antenna

“…Because the spiral antenna feed is balanced and has a characteristic impedance of 188.5 Ω, an impedance‐tapered balun is necessary to transition from a 50 Ω unbalanced coaxial feed. To this end, a linearly tapered microstrip‐to‐parallel stripline was designed and built as well. Figure shows the spiral antenna (with balun) and its reflection coefficient, which exhibits good impedance characteristics over the entire band.…”