An Optimum Design of Paired Balanced Antipodal Vivaldi Antennas With Mirror-Imaged Symmetric Architectures for Ultra-Broadband Characteristics From Microwave to Millimeter-Wave Frequency Ranges

This paper presents a balanced antipodal Vivaldi antenna design to produce ultra-broadband radiations from microwave to millimeter-wave frequencies. In particular, this work relaxes the design constraints to optimize the geometrical parameters to broaden the operational frequency bandwidth, where 147% relative bandwidth has been achieved. Moreover, in this optimized design, the beam squint and cross-polarization (X-pol) discrepancy at high frequencies are improved by pairing two mirror-imaged antenna structures to form an integrated one. The resulted X-pol level can retain good performance in the entire band. The beam squint can be minimized by taking advantage of the 3dB gain increase provided by the array factor. HFSS full-wave simulations first examine the proposed work, further validated by measurement from a basic antenna prototype. The beam squint is less than 3 degrees in the major middle part of the achieved band, and the X-pol level is less than −30dB for the paired antennas.