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Dual-polarized Vivaldi antenna with quarter-wave balun feeding

An ultra-wideband Vivaldi antenna with dual-polarization capability is presented. A two-section quarter-wave balun feedline is developed to feed the tapered slot antenna, which improves the impedance matching performance especially in the low frequency regions. The dual-polarization is realized by orthogonally combining two identical Vivaldi antennas without a galvanic contact. Measured results have been presented with a fractional bandwidth of 172% from 0.56 GHz to 7.36 GHz for S11 < −10 dB and a good port isolation of S21 < −22 dB. The measured antenna gain of up to 9.4 dBi and cross-polarization discrimination (XPD) of more than 18 dB is achieved, making the antenna suitable for mobile communication testing in chambers or open-site facilities.