Characterization of dual-band circularly polarized mushroom-shaped monopole antenna with modified ground plane

Abstract

Abstract In this manuscript, an antenna design configured for dual-band circularly polarized (DBCP) characteristics is presented. The proposed design is quite compact (0.63 λ g × 0.63 λ g × 0.04 λ g) and comprises a mushroom-shaped monopole with a modified ground structure (MGS). In the proposed antenna structure, dual-band CP behavior is generated through a tunable side stub joined orthogonally with the feed patch and reshaping the wide square slot. The impedance bandwidth is measured as 2900 MHz ranging from 1.32 to 4.22 GHz in the lower frequency band (Band 1); however, 980 MHz from 4.78 to 5.76 GHz in the higher frequency band (Band 2). The 3-dB AR bandwidth is measured as 370 MHz (from 3.54 to 3.91 GHz)in the lower frequency band; whereas, it is measured as 650 MHz (from 5.07 to 5.72 GHz) in the higher frequency band. The measured gains spread from 2.5 to 8.3 dBi with a maximum gain of 8.3 dBi in the lower frequency band, whereas 4.8 to 7.05 dBi with a 7.05 dBi maximum gain in the higher frequency band, respectively. The cross-polar rejection is observed greater than 14 dB. Besides, 3-dB half-power beamwidths are seen as 86° & 84°, and 87° & 86° in the x-z and y-z planes for the lower and higher frequency bands, respectively.