Novel compact monopole antennas for global navigation satellite systems

Two novel designs of compact circularly polarized (CP) monopole antennas are proposed and investigated in this paper. The first antenna, consisting of a printed L-shaped monopole and a tilted cross on the ground plane, exhibits 1.160~2.042 GHz (55.10%) measured -10 dB impedance bandwidth, as well as 1.356~1.637 GHz (18.78%) and 1.794~2.487 GHz (32.38%) measured 3 dB AR bandwidths. Antenna 2 with a slant branch on the monopole exhibits an even better performance with 1.122~2.344 GHz (70.44%) measured -10 dB impedance bandwidth, as well as 1.270~ 1.600 GHz (23.00%) and 1.750~2.450 GHz (33.33%) measured 3 dB AR bandwidths. Extensive analyses were conducted on the mechanism of the antennas and the design parameters, including the cable effect. The wideband CP characteristics make these two compact antennas particularly suitable for multi-mode GNSS operations.