Inverted-Sigmoid Shaped Multiband Dielectric Resonator Antenna With Dual-Band Circular Polarization

A multiband dielectric resonator (DR) antenna is proposed with dual-band circularly polarized (CP) response. This antenna consists of an inverted-sigmoid shaped DR. A metallic strip is applied at the surface of the DR to achieve the circular polarization. The fundamental and higher order hybrid modes are excited in the antenna structure because of the specific geometry. The antenna with dual-band CP response provides the measured 3 dB axial ratio (AR) bandwidth of 19.98% in the lower band and 3.07% in the upper band. The upper band 3 dB AR response can be tuned in different 10 dB impedance passbands of the antenna by changing the location and width of the metallic strip. Antenna response can also be tuned to obtain the triple band CP operation.