Abstract: An array antenna including: a frame having a two-dimensional array of a plurality of openings; an electromagnetically radiating tile disposed in each opening; and mounting means for holding at least one tile in a corresponding opening of the frame, each of the mounting means comprising at least two biasing members, each biasing member exerting a biasing force on the tile relative to the frame. Preferably, each biasing member is a leaf spring having first and second ends attached to the frame and a bowed section attached to the tile. Furthermore, it is preferred that each biasing member further have a way to vary the biasing force with temperature, such as fabricating the bow portion from a first and second material, each having a different coefficient of thermal expansion. Also provided is a spacecraft which utilizes the array antenna of the present invention.

Abstract: An array antenna including: a frame having a two-dimensional array of a plurality of openings; an electromagnetically radiating tile disposed in each opening; and mounting means for holding at least one tile in a corresponding opening of the frame, each of the mounting means comprising at least two biasing members, each biasing member exerting a biasing force on the tile relative to the frame. Preferably, each biasing member is a leaf spring having first and second ends attached to the frame and a bowed section attached to the tile. Furthermore, it is preferred that each biasing member further have a way to vary the biasing force with temperature, such as fabricating the bow portion from a first and second material, each having a different coefficient of thermal expansion. Also provided is a spacecraft which utilizes the array antenna of the present invention.

Abstract: Current leakage from high impedance signal circuits or networks of the type useful in the feedback paths of operational amplifiers is inhibited or prevented by circuit guarding. A lower impedance, parallel path provides a guard circuit that protects the signal circuit elements from excessive self-generated current leaks during closed loop use of operational amplifiers. The guard circuit includes equal potential nodes in the lower impedance path that are juxtaposed to corresponding nodes of the signal circuit elements. Current leakages, that may occur in the signal path, are mostly intercepted by the lower impedance guard circuit preventing the formation of electric fields or current leakage paths that would affect normal signal circuit performance.