摘要

Dual-frequency and dual-mode circular patch antennas based on epsilon-negative (ENG) transmission line have been investigated. By input impedance matching, the TM01 mode with omnidirectional radiation pattern and TM11 mode with directional radiation pattern can be excited at two separate frequencies, and then the dual-frequency and dual-mode operation is achieved. Compared with the conventional dual-frequency or dual-mode patch antennas, the new designed antenna only need one patch and one feed. More important, the omnidirectional mode of proposed antenna can be excited at lower frequency than directional mode, and the frequency ratio of the two modes can be tuned by changing the number of the ENG unit cell. The performances of the proposed antennas are studied numerically and experimentally. The measured results are in good agreement with the simulated ones.

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