United States of America As Represented by the Secretary of the Air Force

Mcdonnell Douglas Corporation

Peter R Franchi

Harvey E Tobin

Walter Rotman

Robert J Mailloux

Nicholas V Karas

Ronald L Fante

J Leon Poirier

Marat Davidovitz

Jeffrey Simmers

John D Antonucci

Nicholas P Kernweis

A compact, modular limited-scan phased array is disclosed. The entire array, combining the feed and the radiating elements, is fabricated as a multilayer, planar substrate structure, with vias incorporated as layer interconnects. Furthermore, the desired degree of control over the array pattern can be exercised by inclusion of additional feed circuit layers. The feed can be used in systems requiring limited scan in one of the principal scan planes and wide-angle scan in the other plane, as well as in phased arrays with limited field-of-view in both principal scan planes. The planar circuit implementation of the array makes in inherently amenable to integration with state-of-the-art solid-state active components.

Compact, modular tile architecture for limited field-of-view arrays

A method to measure the far field antenna pattern of an experimental antenna on a smaller range than conventionally used. The basic innovation of the present invention is that the implementation is moved in straight line, toward or away from the antenna under test (AUT), and the measurements are taken while the AUT is rotated about its phase center in a manner that is synchronized with the radial probe.

Linear near field test facility and process

In order to measure the far field antenna pattern of a phased array antenna, the phased array is focused at a probe antenna which is a specific distance away from the aperture. The antenna pattern is then measured by moving the probe antenna on an elliptical arc about the antenna under test.

Elliptical near field test facility

In order to measure the far field antenna pattern of a phased array antenna, the phased array is focused at a probe antenna which is a specific distance away from the aperture. The antenna pattern is then measured by moving the probe antenna on a constant focal arc. This arc minimizes phase aberrations due to defocusing error. To minimize amplitude errors, the pattern of the probe antenna is carefully matched to compensate for the variation induced amplitude error.

ARC range test facility

An electromagnetic stripline coupler apparatus having a pair of coupler units which are separated by a conductive ground plane with a slot in it that is aligned to pass signal energy between the coupler units.

Electromagnetic stripline coupler apparatus

A method for measuring the far field antenna pattern of a large phased array antenna on a conventional far field range by applying a correction factor to the antenna phase shifters. As the antenna is electronically steered to each of its scan angle, a particular correction factor is applied to each radiating elements to correct the far field antenna pattern to the shortened far field range.

Method for measuring large antenna arrays

The sum and difference ports of a conformal phased array monopulse antenna are fed in such a manner as to correct for the degraded radiation pattern which would otherwise occur as a function of scan angle.

Conformal phased array antenna pattern corrector

The bandwidth limitation in space fed phased arrays (that results from the use of phase shifters to implement beam steering) is overcome by a lens arrangement in which independent feeds are provided at the focal plane of the lens. Each feed generates a collimated beam in a different spatial direction. Each beam can then be steered about its central position by means of phase shifters, while retaining a substantially improved bandwidth. An algorithm is derived for designing three-dimensional (3D) microwave lenses with line source feeds by stacking a number of identical two-dimensional (2D) parallel-plate, wide-angle constrained lenses into a cylindrical antenna structure. This lens design provides focused beams over a wide range of scan angles in both elevation and azimuth with only small optical aberration. A wide variety of lens designs can be achieved through this algorithm, dependent upon the constraints which are selected for the 2D lens counterpart. For one design, where all the transmission line lengths in the lens are made equal, the phase errors for beam scanning in the plane containing the cylindrical axis of the antenna are less than their broadside values, regardless of scan angle. This permits wide-angle coverage in both elevation and azimuth from a single lens with both good beam and quality and bandwidth.

Cylindrical microwave lens antenna for wideband scanning applications

An intrusion detection system utilizes a radio frequency radiative system whose near electromagnetic field is monitored by receiving devices which respond, in a measurable way, to any disturbance of the near electromagnetic field by physical intrusion.

Intrusion detection system

An RF intruder system utilizes two concentric loops of wire spaced apart for a predetermined magnitude, either of which can transmit and/or receive electromagnetic energy. This area within the loops are to be protected against intrusion. Without intrusion, the received signal is steady. Upon intrusion, there are signal changes which are instantly noted by signal detection and processing.

RF loop intruder detection system

High gain limited scan operation of phased array antennas is accomplished with microwave circuitry by appropriately coupling the array elements into sub-arrays and establishing a 90.degree. out of phase relationship between even and odd mode power at the aperture of each array element. Even and odd mode power from the feed circuit of each element is coupled to the feed circuit of each nearest adjacent element to form three element overlap subarrays in each plane of scan.

Growing community of inventors

Winchester, MA, United States of America

Peter R Franchi