A novel idea of conformal corrugated edges (CCE) is put forward in this paper for tapered slot antennas to obtain improved low-frequency characteristics. The CCE is realized using conformal slots whose two longitudinal boundary lines are modelled using curvilinear function of the curves that form the tapered slots. So the conformal slots can sufficiently corrugate edges of the tapered slot antennas with one set of structural parameters by comparing with the typical rectangular slot, which makes the corrugated edges design for tapered slot antennas much simpler. Moreover, when used to corrugating edges with the same width of a tapered slot antenna, the conformal slot is longer than the typical rectangular slot, as a result of which the CCE can better improve low-frequency characteristics of the tapered slot antennas. For verification, the CCE using exponential slot is proposed for typical Vivaldi antenna in this paper. Comparisons among antenna structures, port characteristics and radiation characteristics of Vivaldi antennas with the proposed CCE and the typical rectangular slot corrugated edge are carried out, and the Vivaldi antenna with its proposed CCE is fabricated and measured. The remarkable improvement for low-frequency characteristics demonstrates the correctness of the idea.
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