The high cross-polarization of the microstrip integrated balun-fed printed dipole antenna cannot meet the demands of many\nengineering applications. This kind of antennas has high cross-polarization levels (about -20 dB). And we find that the high crosspolarization\nradiation is mainly produced by the microstrip integrated balun rather than the dipole itself. The very limited method\nto lower the cross-polarization level of this kind of antennas is to reduce the substrate thickness. In this paper, to improve the low\ncross-polarized performance, firstly, an equivalentmodel is presented to analyze the cross-polarization radiation. Secondly, a novel\nstructure with low cross-polarization is proposed. The microstrip integrated balun is enclosed by a center slotted cavity.The E-field\nof the microstrip integrated balun is transformed parallel to the dipole arms by the slot, so the radiation of the cross-polarized\ncomponent is suppressed. Measured results show that this structure can achieve a bandwidth wider than 40% while reducing the\ncross-polarization level to less than -35 dB within the frequency band.
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