Circularly polarized omnidirectional microstrip antenna array

Abstract

This paper presents s new circularly polarized (CP) omnidirectional microstrip antenna array. The designed antenna array has back-to-back structure, four series-fed patch antenna elements on each side. The resonant bandwidth of this array is about 7.4% with center frequency 17.5 GHz. The antenna array has CP gain variation in the main lobe plane is around ±2.5 dBic, axial ratio (AR) in the main lobe plane is less than 3 dB, peak CP gain is 9.36 dBic and half-power beam-width is only 15 deg.