Compact Dual-Polarized Ultra-Wideband Cardioid Radiator with Matching Inserts

The article presents the design of the dual-polarization cardioid radiator based on Vivaldi antenna. The aim of the work was to increase the radiator overlap ratio while maintaining ultra-wideband, wide-angle scanning in the angular sector of \u00b160\u00ba and electrical compactness with a height that does not exceed \u03bb at the upper operating frequency due to the use of various matching metal inserts. Their influence on the following radiation characteristics is considered: voltage standing wave ratio, realized gain, efficiency, transmission coefficient, and cross-polarization level, which are obtained in the wide-angle scanning mode in the angular sector of \u00b160\u00b0 in the ultra-wide frequency band when operating on both polarizations. The array cell size is 150 mm \u00d7 150 mm \u00d7 300 mm. It was determined that the use of metal rectangular inserts measuring 25.5 mm \u00d7 145.0 mm at the edges of the radiator allows to expand its operating frequency band, and the use of an additional insert in the aperture allows to improve its matching (radiator with combined inserts). The operating frequency band of the original radiator at the VSWR \u2264 3 level is in the range from 257.6 to 732.5 MHz, which corresponds to an overlap ratio of 2.844. The operating frequency band of the radiator with combined inserts at the same VSWR level is in the range from 164.9 to 677.5 MHz, which corresponds to an overlap ratio of 4.109. The electrical dimension of the proposed radiator at the upper operating frequency of 677.5 MHz is 0.339 \u03bb \u00d7 0.339 \u03bb \u00d7 0.678 \u03bb, and at the lower 164.9 MHz \u2013 0.083 \u03bb \u00d7 0.083 \u03bb \u00d7 0.165 \u03bb. The calculation was performed as part of an infinite antenna array in the Ansys HFSS. The proposed radiator can be used as part of phased arrays for radio communication, radar, and radio navigation systems.