US Government As Represented by the Secretary of the Army

Ralph H Halladay

Michael R Christian

William C Pittman

Brian J Smith

Donald E Lovelace

Richard A Lane

Susan D Terrill

James H Mullins

George A Emmons

William E Read

John C Fleischman

Brenda L Matkin

Raymond C Bates

The system and method for radar calibration using antenna leakage is a simplified means of calibrating the channels in amplitude and phase using natural signal leakage between antennas. It utilizes as calibration signal a wideband sinusoidal Frequency Modulated Continuous Wave (FMCW) waveform with a modulation index and modulation frequency chosen to generate spectral components (or discrete signal frequencies) that fall within the receiver Doppler passband of the radar. The calibration signal is radiated out of the transmitting antenna and enters the radar receiver front-end through the transmit-to-receive antenna leakage which occurs naturally. This technique provides a low-complexity (simpler hardware realization) means for achieving a wideband calibration rapidly and is a practical alternative to the conventional calibration approach that relies on generating offset Doppler signals that are coupled into the radar receiver front-end through the use of couplers and cabling within the radar.

System and method for radar calibration using antenna leakage

The Multiple-Antenna Jamming System (MAJS) is useful for missile-borne jamming of active protection system radars that operate in close proximity to the frequency band of the missile's radio frequency seeker. The MAJS utilizes multiple receiving and transmitting antennas to reduce shadowing effects due to the transmissive radome. It also channelizes the jamming signals into in-seeker-band and out-of-seeker band signals to synchronize the transmission of jamming signals with the emit-listen pattern of the missile seeker and to eliminate the problem of de-sensitizing the RF seeker from the jammer energy. The in-seeker-band jamming signals are transmitted only concurrently with the missile seeker emissions and any signals emanating from an enemy radar are received only during the listen mode of the missile seeker.

Multiple-antenna jamming system

In-Seeker Jamming Device, suitable for an RF missile, utilizes the high-gain antenna and amplifier that are already a part of the missile. During the &ldquo;blind range&rdquo; between the termination of the missile's active tracking of the target at a pre-selected distance from the target and its impact on the target, the Jamming Device produces signals that are broadcast via the missile's antenna and are designed to jam and frustrate the active protection system (APS) radars, thereby rendering the APS radars ineffective and the intended targets vulnerable.

In-seeker jamming device

The millimeter-wave zoom antenna for guiding a beamrider hypervelocity missile uses varying range information derived from the flight of the missile toward the target as control signals for the beam control computer to perform electronically the zooming and the nutation of the millimeter wave guidance beam that emits from a phased array antenna so as to maintain a constant energy density at the missile receiver regardless of the actual distance of the missile from the launch platform at any given time.

Millimeter-wave zoom antenna for guilding beamrider hypervelocity missile

The single channel transceiver with polarization diversity is a target detion and tracking system that results from combining the well-established technology of single channel transceiver with that of microstrip polarization-diverse antenna. The single channel transceiver with polarization diversity transmits a pair of pulses of a pre-selected polarization sense toward a target object and receives two scattered pulses of orthogonal polarizations in rapid sequence. Thereupon, a second pair of pulses, this time of opposite polarization, is transmitted and, again, two scattered pulses of orthogonal polarizations from this second pair of transmitted pulses are received in rapid sequence. Thus, the single channel transceiver with polarization diversity has the capability to obtain the complete scattering matrix of a target by use of four transmitted pulses. The received scattered pulses are further processed by the transceiver to derive the polarization signature that is indicative of the nature of the object from which they scattered in reflection and thereafter used to identify the target among clutter or background.

Single channel transceiver with polarization diversity

A wideband quasi-optical millimeter-wave resonator achieves a wideband frency operation by using a variable dielectric constant photoconducting lens in a Fabry-Perot resonator. Changing the dielectric constant of the lens creates an associated change in the resonant frequency for a given axial mode.

Wideband quasi-optical millimeter-wave resonator

In a phased array radar, simultaneous beam steering and single-sideband mlation is accomplished in the phase shifters in response to phase control signals produced by the beam steering controller and input to the phase shifters. The beam steering controller produces the phase control signals from a pre-selected beam steering angle, a pre-selected radar intermediate frequency and a voltage representing the frequency error from incomplete compensation of the target motion (doppler) of the previous cycle of the radar. Using the phase shifters thusly eliminates the need for an expensive separate component, the single sideband modulator.

Phased array radar with simultaneous beam-steering and single-sideband

A Reduced Radar Cross-Section RF Seeker Front-End interrogates a potential arget by issuing interrogation radiation toward the target and receiving and analyzing a portion of the radiation that reflects back from various surfaces of the targeted object while, at the same time, the Front-End reduces the likelihood of its own discovery by the enemy. The Front-End accomplishes the reduction by absorbing radiation directed toward it by an enemy radar or anti-tactical missile rather than allowing the radiation to be reflected back. Such absorption greatly diminishes the availability of signature reflection that belligerents rely on to identify hostile forces on the battlefield.

Reduced radar cross-section RF seeker front-end

A high-power oscillator which uses a quasi-optical ring resonator to prov the feedback required for oscillation allows energy to travel in one direction only within the resonator and suffers little loss of energy during operation. The oscillator is built by inserting an array of amplifiers, tuned to a desired frequency, into the quasi-optical ring resonator formed by three reflective mirrors. The mirrors are spaced such that the total loop phase shift is equal to an integer multiple of 360 degrees at the desired frequency and, by proper selection of the amplifiers, the loop gain is set to be greater than or equal to one.

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Huntsville, AL, United States of America

Ralph H Halladay