Broadband Metamaterial Aperture Antenna for Coincidence Imaging in Terahertz Band

This paper proposes a broadband metamaterial aperture antenna (BMAA) with a large capacity, low correlation coefficients and high radiation efficiency for coincidence imaging in the terahertz band. The BMAA consists of a random modulated metamaterial aperture and a stripline structure as the feed system. Firstly, a metamaterial element complementary electric-inductor-capacitor (cELC) is designed and a metamaterial aperture is formed via randomly-distributed metamaterial elements with different resonant frequencies. By leveraging the amplitude and the phase modulation characteristics of the metamaterial elements, the BMAA can generate radiation patterns with low correlation coefficients in the range 240-340 GHz. In order to improve the feed efficiency, a stripline structural unit (SSU) is designed and analyzed using an even-odd mode analytical method, and a broadband feed system is designed by cascading SSUs. The performance of the BMAA, including the reflection coefficient, the radiation efficiency and the correlation coefficients of the radiation patterns at different frequencies are then evaluated. The BMAA can solve problems that exist for coincidence imaging, including a narrow working band, lack of measurement modes and low radiation efficiency and offers better results. Finally, a coincidence imaging experiment is implemented using the proposed BMAA and the original image is reconstructed successfully. All results are validated through simulations.