Multiband Monopole Mobile Phone Antenna With Circular Polarization for GNSS Application

A novel design of a multiband monopole mobile phone antenna with circular polarization for GNSS application is presented. The proposed antenna generates four resonant frequencies with branch lines and a shorted parasitic strip to obtain a wide operating band. With the definition of 2.5:1 VSWR, the bandwidth covers several wireless communication systems, including GSM (880 ~ 960 MHz), DCS (1710 ~ 1880 MHz), PCS (1850 ~ 1990 MHz), UMTS (1920 ~ 2170 MHz), WiBro (2300 ~ 2390 MHz) and ISM (2400 ~ 2483 MHz), and also covers GNSS, including COMPASS (1559.052 ~ 1591.788 MHz), GPS (1575.42 ± 5 MHz), GLONASS (1602 ~ 1615.5 MHz). A tuning stub is added to the ground plane and the feeding strip is mounted 45
^°
at the corner to achieve circular polarization for GNSS application. The 3 dB axial ratio (AR) bandwidth (AR-BW) is obtained from 1540 to 1630 MHz, covering the L1 band of GNSS, including COMPASS, GPS and GLONASS. In the 3 dB axial ratio bandwidth, right hand and left hand circularly polarizations are obtained in different broadside directions, with the peak circularly polarized gain of more than 2.7 dBic. An equivalent circuit network is used to analyze the mechanism of circular polarization. Details of the proposed antenna parameters, including return loss, radiation characteristics, and AR spectrum are presented and discussed.