Fiber optic links for millimeter wave communication satellites

Large-aperture phased-array antennas operating at millimeter-wave frequencies are designed for space-based communications and imaging. Array elements are comprised of active transmit/receive (T/R) modules which are linked to the central processing unit through a high-speed fiber-optic network. Experimental results are reported that demonstrate optical control of active modules for satellite communication at 24 GHz. An approach called T/R level data mixing, which utilizes fiber-optic transmission of data signal to individual T/R modules to be upconverted by an optically synchronized local oscillator, is demonstrated at 24 GHz. In this study, a free-running HEMT oscillator, used as a local oscillator at 24 GHz, is synchronized using indirect subharmonic optical injection-locking over a locking range of 14 MHz. Results of data-link performance over 500-1000 MHz is also reported in terms of gain-bandwidth, linearity and third-order intercept, sensitivity, and dynamic range.<>