Optically controlled phased array at C-band

Experiments leading to full optical control of two C-band MMIC (monolithic microwave integrated circuit) subarrays, consisting of 1*4 MMIC T/R (transmit/receive) modules, are discussed. For MMIC-based T/R modules operating best at 5.50 to 5.80 GHz, fiber-optic links at 5 GHz (for reference) and 650+or-150 MHz (for coding/data signals) were selected. The upconverted signal provides a modulated carrier at 5.650 GHz+or-150 MHz for chirp radar operation over 5.6 to 5.8 GHz. The reference signal fiber-optic distribution network at 5 GHz provides frequency reference for synchronization of the two subarray-based local oscillators at 5 GHz to the same carrier center frequency. The same stabilized local oscillators are employed to downconvert the received modulated carrier in the radar received mode. The fiber-optic networks for coding/data signals operate at IF (intermediate frequency) of 650+or-150 MHz. These links are required to have the lowest insertion loss and highest dynamic range over this frequency range.<>