Radiation Enhanced Vivaldi Antenna With Double-Antipodal Structure

Abstract

This letter presents a novel Vivaldi antenna that can be used to the microwave measurement because of the character of near-field linear polarization plane-like waves. Compared to previous double-slot Vivaldi antenna with the same dimension, the proposed antenna's gain, standing-wave ratio, and radiation characteristics are both improved greatly above 12 GHz by the inclusion of the double-antipodal structure, corrugated edges, and a feature called “director.” Furthermore, the double-antipodal structure introduces a coupled E-field; this reduces total cross-polarization level of the antenna. The proposed antenna is measured, and results show that it has a 4.7- to 20-GHz impedance bandwidth and maintains 20-dB copolarization-to-cross-polarization ratio below 10 GHz and 15 dB below 16 GHz, and its gain increases from 10.3 to 14.8 dBi without a significant decline at high frequencies. Symmetrical feed network also results in better symmetry of the beam, especially in H-plane.