Ultrawideband Optically Fed Tightly Coupled Phased Array

We present an optically fed tightly coupled array (TCA) antenna capable of ultrawideband operation ranging from 4-12 GHz. Full-wave simulations have been performed to yield an optimal array design incorporating all required components into the photodiode-integrated antenna model. Various techniques, such as inductance peaking and resistance matching, are employed to overcome inherent constraints in conventional TCAs, thereby improving the operational bandwidth. To demonstrate the concept, an 8 × 8 phased array transmitter, containing four active radiating elements, has been fabricated and integrated on a multilayer high-frequency substrate. The system performance has been evaluated by feeding this array with an optical feed network. The experiment demonstrates that the system possesses ultrawide bandwidth over the frequency range from 4-12 GHz, and wide beam-steering capability up to 40° from the broadside. Electrically controlled optical beam steering is demonstrated and characterized, and far-fields are measured, and compared with simulation results, showing good agreement.