The results are in the general areas of insertion loss and phase and amplitude modulation response. The authors at the Politecnico di Bari, Italy, proposed the beamformer in 1994. The authors describe an optically controlled phased array antenna operating at around 3 GHz. To overcome the limitation of processing over a large bandwidth, they propose an original architecture in which a channelized microwave local oscillator, optically carried, is mixed with the received microwave signals. The systems are entirely fiber based and all necessary time delays are obtained using a single length of high-dispersion optical fiber.
Experimental results are for a three-element system.
The modules can provide up to 128 delay signals simultaneously under one wavelength and control the steering of a whole antenna array. The researchers employ a continuously tunable laser source and take advantage of the dispersion of the holographic grating coupler.