Abstract

A phased array antenna usually consists of a set of nearly identical elemental antennas positioned in an aperture to provide Nyquist spatial sampling for some angular field of view normal to that aperture. The phase of each element is controlled so that the far-field pattern from the array, the 2-D Fourier transform of the aperture field distribution, exhibits the directional properties desired. Normal implementations [Fig. 1(a)] at rf encounter numerous problems including: (1) difficult design of the N-way power splitter driving all elements from one source, (2) diode phase shifters and their control, and (3) a hardware (and weight) concentration at the aperture backplane. This paper describes a design which pursues a significantly different approach,¹ shown in Fig. 1(b). The signal to be applied to each antenna element is generated in an optical subsystem. The power splitting is done by sampling the optical wave front with an array of fibers and the signal is routed to the remotely located antenna by those fibers. Heterodyne detection regenerates the microwave signal as seen in Fig. 1(b). This approach greatly ameliorates the previously mentioned implementation problems.

© 1986 Optical Society of America