Abstract: A tracking antenna system includes coarse (CEA), medium (MEA) and fine (FEA) antenna arrays symmetrically disposed with respect to a boresight (BST) and controllably connectable to signal processing units (SPU) such that the antenna platform (PTF) is moved to point the boresight in the direction of a target while progressively increasing the resolution of the angular difference between the boresight and target. There are provisions for backtracking to decrease the resolution if the angular difference goes out of selected ranges.

Abstract: An angle digitizer receives signal representing the sine and cosine of the angle to be digitized. The voltages are fed to orthogonal pairs of input terminals. Between each two input terminals is a set of equivalued resistors to form a resistor ring. At the junction of each pair of resistors is an output terminal. Each pair of output terminals is connected to the input terminals of a signal amplitude comparator which compares the magnitude of the signals at its inputs to give a digital signal in accordance with which is greater. For each comparator the output terminals of the resistor ring are selected such that the signals are in a direct antiphase relationship.

Abstract: Antenna apparatus for representing a bearing angle includes an antenna array of N antenna elements equispaced around the arc of a circle of at least 90.degree., and preferably greater than 180.degree. in a plane for receiving microwave energy, microwave power dividing and phase transforming matrix having N input ports respectively connected to the antenna elements and a set of output ports connected to a utilization device for indicating the bearing angle of the incoming microwave energy, and a utilization device including means for measuring the phase difference between signals at pairs of the output ports for representing the bearing angle.

Abstract: Signal modulation apparatus includes a PIN diode network which is fed a carrier signal from a carrier signal source and a modulation signal from modulating current output terminal which receives a modulation current directly from a temperature-compensated constant-current amplifier and a signal via a unity gain amplifier from a reference diode which is also fed from the constant-current amplifier which is adapted to receive a modulating signal.

Abstract: Apparatus for digitally indicating the bearing angle of a source of microwave energy includes an antenna array of a plurality of antenna elements equispaced about an arc of a circle in a plane. Connected to each of the antenna elements is a different input port of a microwave power dividing and phase transforming hybrid matrix. Some of the output ports of the matrix are connected to input ports of a plurality of digital phase discriminators whose outputs emit a coded combination of binary level signals. The outputs of the phase discriminators are connected to an ambiguity resolving means which transform the binary level signals to an unambiguous digital word representing the bearing angle.