Balanced Antipodal Vivaldi Antenna with Asymmetric Substrate Cutout and Dual-Scale Slotted Edges for Ultrawideband Operation at Millimeter-Wave Frequencies

This communication examines how to improve the squinted radiation patterns produced by the balanced antipodal Vivaldi antenna (BAVA) while retaining its cross-polarization levels. In particular, we propose discarding the redundant substrate between the metal flares of the BAVA and implementing dual-scale slotted edges to improve the radiation characteristics. The gain at both the lower and the higher end of the band is significantly enhanced without increasing the antenna size. Moreover, significant reduction in the beam squint relative to the conventional BAVA designs is achieved. A microstrip-to-stripline transition is also introduced to improve low-end matching. The final design operates over 10-40 GHz with return loss <-10 dB, providing sufficient bandwidth and match for a variety of applications at millimeter-wave frequencies. Numerical and experimental assessments to validate the proposed antenna design are conducted.