Self-Oscillating Active Integrated Antenna With Harmonic Suppression Using Metamaterial Resonators and Ground Radiation

A self-oscillating active integrated antenna (AIA) with harmonic suppression using metamaterial resonators and ground radiation is proposed and investigated. Two composite right-/left-handed (CRLH) cells are connected in parallel and operated at negative first-order mode as the left-handed resonators to serve as the frequency selective element and the feedback path of the oscillating circuit at the same time. Meanwhile, the radiation parameters are independently controlled by exciting dipole-like ground-mode radiation using the CRLH cells. Benefiting from the high-quality factor of the CRLH cells and the newly added harmonic choking filters, the proposed AIA shows extraordinarily low phase noise, along with notable radiation parameters and good dc-to-RF conversion efficiency. The design principle, linear and nonlinear simulated data, and experimental results are carefully discussed and validated.