Hazeltine Corporation

Paul H Feldman

Alfred R Lopez

Gary A Schay

Joseph B Gencorelli

A field monitor in the near field receives an antenna signal which approximates that which would be received by the monitor if located in the far field. In one aspect of the invention, the antenna signal is produced by an array of spaced apart receiving elements. In another aspect of the invention, the signal received from a near field sampling antenna is passed through a signal processor having the necessary characteristics to construct from the sample a signal corresponding to that which would have been received in the far field. Antenna element arrays are also used as plane wave sources permitting antenna testing with a radiating path length of one-eighth or one-quarter of the far field distance. Compact indoor antenna test ranges are also provided.

Near field antenna measurement systems and methods

An amplitude control system particularly suitable for an active antenna array includes a power detector for generating a power level signal representative of a level of radio frequency (RF) energy radiated by an antenna element, or groups of elements, in a phased antenna array. A reference signal corresponding to a desired value for the radiated level of RF energy is set by a control device, and the power level signal and the reference signal are compared with one another. Depending on the comparison result, an attenuator associated with an RF amplifier than drives the antenna elements, is adjusted to maintain the radiated RF energy at the desired value set at the control device.

Active array element amplitude stabilization

Proper operation of a system fault monitor is verified while the monitor is coupled on-line with the system and to an alarm line. During periods when actual system signals are produced, the monitor is coupled through one of two time delay circuits to the alarm line. During periods when no actual signals are produced by the system, the monitor input is switched to an error signal generator and the monitor output is coupled through the other time delay circuit to processing circuitry which detects the presence of the alarm signal after the circuit time delay. If no alarm signal is detected, a failure of the monitor and/or delay circuit is indicated.

Verification of on-line fault monitor performance

Proper operation of a beam steering unit for a phase array antenna, is verified by simulating the pattern of wave energy which would be radiated to an observation point in space when the beam steering unit is connected to phase shifters associated with elements of the antenna. The simulated pattern thus obtained may be compared with a preset pattern for the observation point during a scanning operation of the beam steering unit, and an alarm or other indication is obtained when the difference between the simulated and the preset pattern exceeds a certain limit. The simulated pattern is obtained by storing phase angle data from the beam steering unit in a memory at areas corresponding to phase shifters associated with elements of the phased array antenna. Observation angle data corresponding to the angle of the point in space relative to the antenna array is generated, the observation angle data being a function of observation angle, antenna element spacing and radiation wavelength.

Beam steering unit real time angular monitor

Proper operation of an RF diode digital phase shifter of the kind having a number of logic inputs to effect corresponding incremental shifts in the phase of an RF signal passing through the phase shifter, is determined by monitoring the voltages developed across resistance elements of driver stages associated with diodes of the phase shifter. Voltages developed across the diodes are monitored, while turning the driver stages on and off in certain sequences and comparing the levels of the monitored voltages with preset reference levels. The drive stages also can be tested by turning them on and off simultaneously. A fault condition is indicated when the monitored voltages deviate from preset levels.

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Commack, NY, United States of America

Paul H Feldman