{'fraction_non_alphanumeric': 0.018779342723004695, 'fraction_numerical': 0.010328638497652582, 'mean_word_length': 5.091428571428572, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
A novel corrugated four slot Vivaldi antenna loaded with metamaterial cells for microwave imaging

In this paper, a new four slot Vivaldi antenna (FSVA) having improved directivity is proposed for the microwave imaging applications. The antenna is designed to operate over a wide band in the frequency range of 1.15–12 GHz. The lower frequency response of the antenna is improved by modifying the microstrip-slot line balun transition, and by introducing corrugations at the aperture. Further, approximately 1 dB increase in directivity is obtained by loading the antenna with anisotropic zero index metamaterial cells. The obtained directivity is above 8 dBi throughout the operating frequency range having its maximum value of 14.3 dBi. The parameters of the designed antenna are optimized using the CST Microwave studio. The designed structure is fabricated on a FR-4 substrate, and its return loss and radiation characteristics are measured. Finally, the antenna is tested for microwave imaging application to find a metal body hidden deep inside standard sand.