A new approach for feeding sinuous antenna

The complexity of feeding a four arms sinuous antenna using microstrip balun, causes limitation on the use of standard feed point structure. In this paper a new feeding structure in the form of microstrip line is proposed that can improve the axial ratio (AR), and nonsymmetrical radiation pattern. Simulation shows that the AR remains below 2.5 dB in a frequency band 2–5 GHz, which is about 2.5 dB lower as compared to other proposed configurations. A prototype of proposed feeding structure was fabricated and tested. Good agreement observed between simulation results and measurements.