System architecture of MMIC-based large aperture arrays for space application

The persistent trend to use millimeter-wave frequencies for satellite communications presents the challenge to design large-aperture phased arrays for space applications. These arrays, which comprise 100 to 10,000 elements, are now possible due to the advent of lightwave technology and the availability of monolithic microwave integrated circuits. In this paper, system aspects of optically controlled array design are studied. In particular, two architectures for a 40 GHz array are outlined, and the main system-related issues are examined: power budget, synchronization in frequency and phase, and stochastic effects

W-4 PHASE AND FREQUENCY COHERENCY OF MULTIPLE OPTICALLY SYNCHRONIZED 20GHZ FET OSCILLATORS FOR SATELLITE COMMUNICATIONS

ABSTRACT Future generation of communication satellites are based on large aperture phased array antennas, which are composed of many active transmit/receive modules. The phase and frequency coherency of these modules are of concern. A viable technique to provide phase and frequency references for synchronization is through fiber-optic distribution and using indirect subharmonic optical injection locking techniques. Experimental results of phase and frequency coherency of two 20GHz FET oscillators are reported in this paper. Optimum performance was achieved at subharmonic factor of 1/4 with locking range of 84MHz ancl phase noise degradation of only 14 dB. Initial phase coherency measurements of two injection locked oscillators indicate that a phase error can be introduced due to the detuning between the slave and master oscillator signals. A scheme to correct for this phase error is also presented

To develop a dynamic model of a collector loop for purpose of improved control of solar heating and cooling. Final technical report. [TRNSYS code]

The program objectives were to (1) assess the feasibility of using the TRNSYS computer code for solar heating and cooling control studies and modify it wherever possible, and (2) develop a new dynamic model of the solar collector which reflects the performance of the collector under transient conditions. Also, the sensitivity of the performance of this model to the various system parameters such as collector time constants, flow rates, turn-on and turn-off temperature set points, solar insolation, etc., was studied. Results are presented and discussed. (WHK