Wideband orthogonal square monopole antennas with semi-circular base

摘要

A planar circular disc monopole (CDM) antenna gives an impedance bandwidth of 1:10.2 [1, 2]. Various other planar configurations such as elliptical, square, rectangular and hexagonal monopoles have also been reported [3]. Out of these geometries, elliptical disc monopoles with ellipticity patio m 1.1 yielded maximum bandwidth of 1:10.7. The large bandwidth of these antennas is due to the overlapping of their various resonant modes. The reported square monopole (SM) with dimensions of 45 mm × 45 mm and fed at the middle of the edge did not give large bandwith. However, by changing the feed-point location, the bandwidth has been increased [3]. Further increase in the bandwidth has been achieved by replacing the lower half of the square with semi-circular bane. For all the above planar monopole antennas, the azimuth radiation pattern does not remain omnidirectional at all the frequencies because of asymmetry of the configuration in the two orthogonal planes. A new configuration of orthogonal SM with semi-circular base has been proposed, which gives omni directional radiation pattern with wide bandwidth.