Ultra wide band antenna element

Antenna unit cells suitable for use in antenna arrays are disclosed, as are antenna array and mounting platform such as an aircraft comprising antenna unit cells. In one embodiment, an antenna unit cell comprises a dielectric substrate having a length extending along a first axis and a width extending along a second axis, a first plurality of radiating elements disposed on a first side of the dielectric substrate, and a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, wherein the second plurality of radiating elements extend to an edge of the unit cell, and the first plurality of radiating elements overlap portions of the second plurality of radiating elements. Other embodiments may be described.

BACKGROUND

The subject matter described herein relates to electronic communication and sensor systems and specifically to configurations for antenna arrays for use in such systems.

Microwave antennas may be constructed in a variety of configurations for various applications, such as satellite reception, remote sensing or military communication. Printed circuit antennas generally provide antenna structures which are low-cost, lightweight, low-profile and relatively easy to mass produce. Such antennas may be designed in arrays and used for radio frequency systems such as identification of friend/foe (IFF) systems, electronic warfare systems, signals intelligence systems, personal communication service (PCS) systems, satellite communication systems, etc.

Recently, interest has developed in ultra-wide bandwidth (UWB) arrays for use in communication and sensor systems. Thus there is a need for a lightweight phased array antenna with a wide frequency bandwidth and a wide angular scan range and that is conformally mountable to a platform surface.

SUMMARY

In one embodiment, an antenna unit cell comprises a dielectric substrate having a length extending along a first axis and a width extending along a second axis, a first plurality of radiating elements disposed on a first side of the dielectric substrate, and a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, wherein the second plurality of radiating elements extend to an edge of the unit cell, and the first plurality of radiating elements overlap portions of the second plurality of radiating elements.

In another embodiment, an antenna array comprises a plurality of unit cells, at least a plurality of the unit cells comprising a dielectric substrate having a length extending along a first axis and a width extending along a second axis, a first plurality of radiating elements disposed on a first side of the dielectric substrate, and a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, wherein the second plurality of radiating elements extend to an edge of the unit cell, and the first plurality of radiating elements overlap portions of the second plurality of radiating elements.

In a further embodiment, a mounting platform such as an aircraft, naval vessel, or ground vehicle comprises a RF communication system, radar, electronic warfare systems, signals intelligence systems, or other RF sensors; and an antenna assembly coupled to the RF system and comprising a plurality of unit cells, at least a plurality of the unit cells comprising a dielectric substrate having a length extending along a first axis and a width extending along a second axis, a first plurality of radiating elements disposed on a first side of the dielectric substrate, and a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, wherein the second plurality of radiating elements extend to an edge of the unit cell, and the first plurality of radiating elements overlap portions of the second plurality of radiating elements.

In a further embodiment, a method to make an antenna assembly comprises printing a first plurality of radiating elements on a first surface of a substrate, wherein the first plurality of radiating elements are arranged in groups of opposing pairs that form a bow-tie shape disposed about a central point, and printing a second plurality of radiating elements on a second surface, opposite the first surface, of the substrate, wherein the second plurality of radiating elements are trapezoidal in shape and arranged to form opposing bow-tie shapes disposed about the central point, and the first plurality of radiating elements are trapezoidal in shape and partially overlap the second plurality of radiating elements.

In a further embodiment, a method to use an antenna assembly comprises providing an antenna array comprising a plurality of unit cells, at least a subset of the unit cells comprising a dielectric substrate having a length extending along a first axis and a width extending along a second axis, a first plurality of radiating elements disposed on a first side of the dielectric substrate, and a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, wherein the second plurality of radiating elements extend to an edge of the unit cell, and the first plurality of radiating elements overlap portions of the second plurality of radiating elements, and coupling one or more feed pins to the first plurality of radiating elements and to an RF signal source for transmission.

DETAILED DESCRIPTION

Configurations for antenna unit cells suitable for use in array antenna systems, and antenna systems incorporating such unit cells are described herein. Specific details of certain embodiments are set forth in the following description and the associated figures to provide a thorough understanding of such embodiments. One skilled in the art will understand, however, that alternate embodiments may be practiced without several of the details described in the following description.

The invention may be described herein in terms of functional and/or logical block components and various processing steps. For the sake of brevity, conventional techniques related to electronic warfare, radar, signal intelligence systems, data transmission, signaling, network control, and other functional aspects of the systems (and the individual operating components of the systems) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent example functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical embodiment.

The following description may refer to components or features being “connected” or “coupled” or “bonded” together. As used herein, unless expressly stated otherwise, “connected” means that one component/feature is in direct physically contact with another component/feature. Likewise, unless expressly stated otherwise, “coupled” or “bonded” means that one component/feature is directly or indirectly joined to (or directly or indirectly communicates with) another component/feature, and not necessarily directly physically connected. Thus, although the figures may depict example arrangements of elements, additional intervening elements, devices, features, or components may be present in an actual embodiment.

FIG. 1is a schematic top-view of an antenna unit cell, according to embodiments, andFIG. 2is a schematic side elevation view of the antenna unit cell depicted inFIG. 1. Referring toFIGS. 1-2, in some embodiments an antenna unit cell100comprises a dielectric substrate110having a length, L, extending along a first axis102and a width, W, extending along a second axis104, and a thickness, t. In some embodiments the antenna unit cell100is adapted to operate in a frequency range extending from about 300.0 MHz to 3.0 GHz, (i.e., a wavelength of about 100 cm to 10 cm). In such embodiments the length L and the width W measure between about 1.5 inches (38.1 mm) and 2.0 inches (50.8 mm) and the thickness, t, of the substrate measures approximately 30 mils (0.762 mm). The design scales geometrically to any 10:1 band (i.e., 2-20 GHz, 0.5-5 GHz). One skilled in the art will recognize that the particular dimensions of the antenna unit cell100may be a function of the design frequency as well as materials and physical configuration of the unit cell. In some embodiments the substrate110may be formed from a conventional substrate, e.g., a Rogers 4350 series dielectric material.

A first plurality of radiating elements120A,120B,120C,120D, which may be referred to collectively by reference numeral120, are disposed on a first side112of the dielectric substrate110. Radiating elements120may be coupled to a feed line150via one or more contacts130A,130B,130C,130D, which may be referred to collectively by reference numeral130, such that radiating elements120define a feed network. In some embodiments the contacts130extend through vias118formed in the substrate110. In some embodiments the contacts130may be formed integrally with the radiating elements, while in other embodiments the contacts130may be formed separately and electrically coupled to the radiating elements. In some embodiments the first plurality of radiating elements120measure between about 0.5 inches and 0.7 inches in length and extend from the central feed line150to a point that is a distance D from the edge116of the unit cell. In some embodiments the distance D1may measure between 0.13 inches (3.3 mm) and 0.18 inches (4.57 mm).

A second plurality of radiating elements140A,140B,140C,140D, which may be referred to collectively by reference numeral140are disposed on a second side114of the dielectric substrate110. In some embodiments the second plurality of radiating elements140overlap portions of the first radiating elements140, such that the second plurality of radiating elements140may be capacitively coupled to the first plurality of radiating elements120that define the feed network. In some embodiments the first plurality of radiating elements120measure between about 0.5 inches and 0.8 inches in length and extend from the edge116of the unit cell110to a point that is a distance D2from the feed line150of the unit cell. In some embodiments the distance D2may measure between 0.2 inches (5.08 mm) and 0.5 inches (12.7 mm).

In the embodiment depicted inFIGS. 1-2the radiating elements120are substantially trapezoidal in shape and are arranged to form opposing bow-tie shaped radiating elements. The bow-tie radiating elements are oriented at ninety (90) degrees with respect to one another to provide a dual-polarization antenna structure. One skilled in the art will recognize that the radiating elements120,140may be formed in various shapes and sizes.

In practice, a plurality of unit cells110may be positioned adjacent one another to define an antenna array.FIG. 3is a schematic top, plan view of an antenna array formed from a plurality of unit cells, according to embodiment, andFIG. 4is a schematic side elevation view of the antenna array depicted inFIG. 3. In the embodiment depicted inFIGS. 3-4, four antenna unit cells100are arranged to form a 2×2 antenna array. One skilled in the art will recognize that any number of unit cells may be combined to form an m×n antenna array.

Referring toFIGS. 3-4, in relevant part when the antenna unit cells100are arranged to form a 2×2 array adjacent radiating elements in the first plurality of radiating elements120are separated by a distance that measures twice the distance D1, i.e., 2D1. Thus, referring toFIGS. 3-4, adjacent elements120A and120C are separated by a distance of 2D1, as are elements120B and120D. By contrast, adjacent radiating elements in the second plurality of radiating elements140are in electrical contact with one another. Thus, as illustrated inFIGS. 3-4, radiating elements140A,140C are electrically connected, as are radiating elements140B,140D.

In some embodiments the antenna assembly may be formed by printing the respective radiating elements120,140on opposing sides of a sheet of dielectric substrate. This may be illustrated with respect toFIGS. 5-6.FIG. 5is a schematic top, plan view of a printed antenna assembly, according to embodiments, andFIG. 6is a schematic bottom, plan view of a printed antenna assembly, according to embodiments. Referring toFIG. 5-6, a pattern of radiating elements120may be printed on a first surface of a substrate110, while a pattern of radiating elements140may be printed on the opposing second surface of substrate110. The resulting sheet may then be cut as desired to form an m×n array of antenna elements.

FIG. 7is a schematic illustration of an antenna assembly700, according to embodiments. Referring toFIG. 7, in a conformal antenna assembly the substrate layer110and the printed radiating layers120,140may be positioned between one or more foam layers720and a ground plane710. Optionally, a cap layer730may be positioned over the foam layer720. The feed pins150may be coupled to a signal source for transmission.

In some embodiments an aircraft-based antenna or phased array system may incorporate one or more antennas constructed according to embodiments described herein. By way of example, referring toFIG. 8, an antenna assembly700may be mounted on an aircraft800, such as an airplane, helicopter, spacecraft or the like. In alternate embodiments an antenna assembly700may be mounted on a ground-based vehicle such as a truck, tank, train, or the like, or on a water-based vehicle such as a ship. In further embodiments an antenna700may be mounted on a land-based communication station.

Thus, described herein is an ultra-wide band (UWB) antenna unit cell and assembly. The antenna element may be used in the creation of wide-band arrays and/or conformal antennas that achieves ultra wide bandwidth (i.e., a 10:1 frequency band edge ratio), the ability to perform over wide scan angles, and provides both dual and separable RF polarization capability. In some embodiments the unit cell that employs a multi-layer circuit that comprises a bow-tie fan feed layer, and a layer comprising bow-tie based connected array. The circuit board may be placed over a ground plane with foam dielectric layers below and above the antenna circuit board to create the antenna element structure. A differential feed from bow-tie like fan elements is coupled capacitively to the underlying unit-cell to unit-cell connected bow-tie element layer. Such an antenna has wide applicability to communication phased antenna arrays (PAA), signal intelligence sensors and detection sensor arrays, wide band radar systems, and phased arrays used in electronic warfare.

An antenna element manufactured in accordance herewith exhibits ultra-wide bandwidth and better than 55-degree conical scan volume for the creation of conformal arrays and antennas. The design approach provides effective gain within 2 dB of the ideal gain possible for the surface area of the unit-cell for the element. The element design can be used as a wide-band antenna and/or array. The design can be scaled to any frequency band with a 10:1 ratio from the highest to the lowest frequency of desired coverage.