Broadband Circularly Polarized Crossed Bowtie Dipole Antenna Loaded With Parasitic Elements

An extremely broadband circularly polarized (CP) antenna is presented. The proposed antenna consists of a crossed bowtie dipole loaded with four unequal parasitic cross slots, four parasitic bowtie patches, and four parasitic rectangular strips. The cross slots can generate a CP mode due to the sequential phases of the crossed bowtie dipole. The parasitic bowtie patches are gap-coupled with two arms of the crossed bowtie dipole, and they are sequentially rotated along diagonals to generate an additional CP mode. The parasitic strips also generate one CP mode due to the sequentially rotated configuration parallel to the crossed bowtie dipole. By properly combining with two CP modes of the crossed bowtie dipole, broadband CP operation is achieved. The experimental and simulated results are in agreement, and the measured results show that the proposed antenna exhibits a very wide impedance bandwidth of 93.1% (2.21-6.06 GHz) and an excellent axial-ratio bandwidth of 90.9% (2.2-6.4 GHz). In addition, the proposed antenna produces a right-hand circular polarization with a peak gain of 8.6 dBi.