Analysis of printed archimedean and single ended bifilar spirals for wireless applications

Printed spiral has long been a common preference in Radio Frequency (RF) and microwave engineering. Nowadays, they are widely implemented in wireless power system, wireless communication, semiconductor and power system. In this paper, analysis of electrical properties is performed closely on traditional Archimedean and Single Ended Bifilar (SEB) spirals in order to investigate the potential for different wireless technology. Comparison is focused on the resistance (R), inductance (L), quality factor (Q), S parameters (S) and far field radiation efficiency. The traces of Archimedean and SEB spirals are intentionally constructed with nearly identical length, which are 690.7586 mm and 694.2531 mm respectively. Additionally, the spirals are designed on the FR-4 substrate of the same size and the frequency of investigation is 1 to 100 MHz for RLQ parameter and up to 1000 MHz for S₁₁ magnitude. Under strict comparison criteria, the Archimedean spiral is apparently simpler and offers higher Q factor due to the lower resistance in overall whilst the bifilar spiral has the potential for wideband application and it provides higher inductance than Archimedean spiral before the self-resonance frequency (SRF). In short, the close comparison of two popular spirals provides useful perceptions to RF and microwave system engineering.