An active phased array antenna packaging scheme

Abstract

Active phased array antennas use a large number of TransmiVReceive (T/R) modules at the antenna aperture. These antennas require complex RF power dividedcombiner beamforming networks. DC power is generally provided by distributing power supplies at the antenna aperture that provide DC power to a group of T/R modules. High power T/R modules for phased arrays typically require liquid cooling. A typical phased array, then, might have a large number of RF, DC and logic connections at the antenna aperture.Since most of the active components are distributed at the aperture, in order to maintain the antenna performance, it is necessary to provide a means of easily replacing these components when they fail.A typical phased array will have thousands of RF, DC, logic and fluid connections. We describe a packaging scheme for an active phased array antenna that is easy to maintain, and requires very few disconnections for repairs A fabricated demonstration array and associated components are shown in Figures 1 and 2.The antenna incorporates the use of a monolithic faceplate, machined with great precision in order to achieve a set number of waveguide radiating elements, which form the antenna aperture. The machined radiating elements are capped off with a dielectric window, which is bonded in place, to provide protection against environmental and operating extremes.The T/R Modules/Control Modules/Power Supplies/Combiners and Power and Logic busses are mounted directly to vacuum brazed liquid cooled cold plates. These cold plates perform a dual function, as an integral part of the antenna structure and the means of controlling component temperatures by efficiently removing dissipated heat during antenna operation. Each cold plate has components mounted on both sides, using a built-in component offset to maintain the specified component element spacing and pattern. The use of vacuum brazed cold plates provides the flexibility to direct the coolant flow in the most efficient manner possible, in order to maximize the heat removal on critical (high power) components, thus decreasing junction temperatures and increasing operational life. The vacuum brazing feature also yields design flexibility, in that the brazing operation is fluxless and there is no requirement to include large voided areas in the cold plate for flux washout. *Retired 1608