Modified equiangular spiral antennas side-fed by multi-stage wideband impedance transforming transitions

Abstract

This paper shows the design process and measurement data for a modified bi-directional equiangular spiral antenna fed by a microstrip to parallelstrip to twin-line transition on two substrates (20-mil thickness) with three layers (aligned vertically). By etching holes out of the spiral arms at the locations where the tapered parallel-strip line passed underneath, the impedance mismatch caused by the proximity of the spiral's metal layer to the parallel-strip line was reduced. Between 4 and 7 GHz, this antenna exhibits a typical radiation pattern for equiangular spiral antennas. Measured and simulated radiation patterns and VSWR plots for this frequency range show good performance.

A miniaturized spiral antenna for energy harvesting of implantable medical devices

“…The spiral antenna was investigated previously [3] and feeding of the antenna can be done either from the center or side end of the spiral antenna. The concept of side-fed spiral antenna [4,5] and center-fed spiral antenna [6,8] are well known. Several different possible configurations of spiral antenna have been presented lately like flexible double arm side fed circular spiral antenna with microstrip infinite balun for wearable applications [7].…”

Flexible spiral antenna with microstrip tapered infinite balun for wearable applications

“…The concept of side-fed spiral antennas is well known [1,2], and the feed with microstrip tapered infinite balun combines the concept of the infinite balun [3,4] with proper impedance matching. However, the differences are first the use of flexible Rogers material, and secondly the use of one arm of the spiral antenna as the ground for a microstrip transmission line, which is the novelty.…”