Circularly symmetric tightly coupled dipole array with non-coincident phase center

An antenna array includes a printed circuit board including printed circuit board elements circumferentially disposed at locations on a surface of the printed circuit board. The printed circuit board elements are disposed in opposing pairs at diametrically opposite locations and include a first member and a second member. The first member intersects the second member which is curved. The antenna array can be an ultra-ultra wide band (UUWB) wavelength scaled array (WSA) tightly coupled dipole array (TCDA) active electronically scanned array (AESA) aperture.

BACKGROUND

Embodiments of inventive concepts disclosed herein relate generally to antenna arrays including but not limited to a tightly coupled dipole array (TCDA).

Modern sensing and communication systems may utilize various types of antennas to provide a variety of functions, such as communication, radar, and sensing functions. For example, ultra-high frequency (UHF) and very high frequency (VHF) radio systems use directional and omnidirectional antenna arrays for data and voice communication. In another example, radar systems use antenna arrays to perform functions including but not limited to: sensing, intelligence gathering (e.g., signals intelligence, or SIGINT), direction finding (DF), electronic countermeasure (ECM) or self-protection (ESP), electronic support (ES), electronic attack (EA) and the like. An ultra-ultra wide band (UUWB) Wavelength Scaled Array (WSA) TCDA Active Electronically Scanned Array (AESA) Aperture that has rotationally symmetric radiation properties in the far field radiating is difficult to achieve with conventional manufacturing techniques.

SUMMARY

In one aspect, embodiments of the inventive concepts disclosed herein are directed to an antenna array. The antenna array includes a substrate having a surface and first members and second members. The second members are arranged about a first circumference about a center point on the surface of the substrate. The first members extend radially with respect to the center point, and the second members are curved. The antenna array also includes third members and further members. The fourth members are arranged about a second circumference about the center point on the surface of the substrate. The first circumference is smaller than the second circumference. The third members extend radially with respect to the center point, and the fourth members are curved.

In a further aspect, embodiments of the inventive concepts disclosed herein are directed to an antenna system. The antenna system includes a printed circuit board including printed circuit board elements including first arched elements circumferentially disposed on a surface of the printed circuit board at diametrically opposite locations and second linear elements disposed radially at diametrically opposite locations. The antenna system further includes a polarization synthesis network coupled to the printed circuit board elements. The polarization synthesis network is configured to compensate for non-orthogonal polarization associated with a pair comprising one of the first arched elements and one of the linear elements.

In a further aspect, embodiments of the inventive concepts disclosed herein are directed to a method. The method includes providing a substrate, providing at least four first elements at locations along a circumference on the substrate, and providing at least four second elements radially with respect to the circumference. The first elements are curved, and the second elements are linear. The elements are disposed such that a pair of a first element of the first elements and a second element of the second elements effectively have non-orthogonal linear polarization due to parasitic cross polarization cancellation. The method also includes providing a polarization synthesis network coupled to the pair to provide arbitrary polarization.

DETAILED DESCRIPTION

Before describing in detail embodiments of the inventive concepts disclosed herein, it should be observed that the inventive concepts disclosed herein include, but are not limited to a novel structural combination of components and circuits disclosed herein, and not to the particular detailed configurations thereof. Accordingly, the structure, methods, functions, control and arrangement of components and circuits have, for the most part, been illustrated in the drawings by readily understandable block representations and schematic diagrams, in order not to obscure the disclosure with structural details which will be readily apparent to those skilled in the art, having the benefit of the description herein. Further, the inventive concepts disclosed herein are not limited to the particular embodiments depicted in the diagrams provided in this disclosure, but should be construed in accordance with the language in the claims.

Some embodiments of the inventive concepts disclosed herein are directed to an aperture (e.g., a UUWB WSA TCDA AESA aperture) that has dual polarized rotationally symmetric radiation properties in the far field radiating zone (e.g. beam width, gain, etc.). In some embodiments, the rotationally symmetric radiation properties of a directional antenna achieves advantages for RF sensor systems, such as a radar or other sensor. The UUWB aperture implementation realizes near constant radiation properties over very large bandwidths (e.g., greater than 10:1 instantaneous bandwidth (IBW)) in some embodiments. In some embodiments, the array provides UUWB performance for multifunction radio frequency (MFRF) type applications with high polarization purity. In some embodiments, the AESA array is utilized in UUWB signal intelligence (SIGINT) receiver systems (e.g., photonic, RF over optical radio) and/or other advanced radio and radar systems. In some embodiments, the systems and methods provide new wideband system array layout schemes for AESA technology.

In some embodiments, the aperture is provided in a configuration (e.g., with subarrays with uninterrupted element lattice spacing) that can be more easily manufactured. In some embodiments, the aperture is provided in a configuration (e.g., with subarrays with uninterrupted element lattice spacing implementation) that can be provided using tiles including antenna elements that are joined together. In some embodiments, the aperture is provided in a planar and/or conformal WSA UUWB TCDA aperture topology with non-coincident phase centers. The manufacturing techniques, devices and configurations described in U.S. patent application Ser. No. 15/970,781, filed May 3, 2018, “Systems and Methods for Wavelength Scaled Array Layout Optimization, U.S. patent application Ser. No. 15/825,711, filed Nov. 29, 2017, “Polarization Control For Electronically Scanned Arrays,” U.S. patent application Ser. No. 16/021,784, filed Jun. 28, 2018, “Circularly Symmetric Tightly Coupled Dipole Array,” U.S. patent application Ser. No. 15/972,608, filed May 7, 2018, and U.S. patent application Ser. No. 15/160,959, filed May 20, 2016 can be utilized in some embodiments; each of the above listed applications is incorporated herein by reference in its entirety and assigned to the assignee of the present application.

Referring toFIG. 1, an antenna system100for a communication, radar, or sensing system includes an antenna array110(e.g., a circularly shaped ESA array) of antenna elements112. The antenna array110is provided on a substrate, such as, a printed circuit board substrate or other structure in some embodiments. In some embodiments, the antenna array110is disposed on multiple circuit boards, such as according to the subarray architecture described in U.S. application Ser. No. 16/103,742 filed Aug. 14, 2018, and U.S. application Ser. No. 16/123,854 filed Sep. 6, 2018, both incorporated herein by reference in their entireties. In some embodiments, the antenna system100is for a sensing radar system or electronic warfare radar system (e.g., UUWB signal intelligence (SIGINT) receiver systems such as photonic RF over optical radio systems).

In some embodiments, the antenna system100is a UUWB WSA TCDA AESA aperture. The antenna array110is shown on a Cartesian plane including an X-axis113and a Y-axis115. The X-axis113extends from a negative meter position to a positive meter position, and the Y-axis115extends from a negative meter position to a positive meter position. Although particular sizes are shown for the array110inFIG. 1, the sizes and dimensions are exemplary and other sizes and dimensions can be used depending upon system criteria and operational parameters. In some embodiments, the antenna array can have an X-axis113that extends from a negative 0.4 meter position to a positive 0.4 meter position, and a Y-axis115that extends from a negative 0.4 meter position to a positive 0.4 meter position. In some embodiments, the antenna array can have an X-axis113that extends from a negative 0.9 meter position to a positive 0.9 meter position, and a Y-axis115that extends from a negative 0.9 meter position to a positive 0.9 meter position.

As shown inFIG. 1, the antenna array110is formed of circumferentially disposed antenna elements112about a center118. The antenna elements112include first elements114disposed at a first distance116from the center118along a circumference, second elements124disposed at a second distance126from the center118along the circumference, third elements134disposed at a first distance136from the center118along a circumference, fourth elements144disposed at a fourth distance146from the center118along the circumference, fifth elements154disposed at a fifth distance156from the center118along the circumference, sixth elements164disposed at a sixth distance166from the center118along the circumference, seventh elements174disposed at a seventh distance176from the center118along the circumference, eighth elements184disposed at an eight distance186from the center118along the circumference, ninth elements194disposed at a ninth distance196from the center118along the circumference, tenth elements204disposed at a tenth distance206from the center118along the circumference, and eleventh elements214disposed at an eleventh distance216from the center118along the circumference. Although eleven sets of the antenna elements112are shown inFIG. 1, other numbers of circumferential sets of antenna elements112can be utilized.

As shown inFIG. 1, the distance between neighboring elements114,124,134,144,154,164,174,184,194,204, and214decreases the closer the element is to the center118in some embodiments. The elements114,124,134,144,154,164,174,184,194,204, and214are smaller in area (e.g., effective area) the closer the element is to the center118in some embodiments. Such a configuration of spacing and element sizes provides for the dense pattern of the antenna elements112in some embodiments. The number of the elements114,124,134,144,154,164,174,184,194,204, and214at the respective distances116,126,136,146,156,166,176,186,196,206, and216can be any number from4to N where N is an integer in some embodiments. The number of the elements114,124,134,144,154,164,174,184,194,204, and214at the respective distances116,126,136,146,156,166,176,186,196,206, and216can be different from each other in some embodiments. The total number of elements (e.g., 303 in as shown inFIG. 1) varies according to system criteria and operational parameters.

The layout for antenna elements112is provided as a wavelength scaled array (WSA) (e.g., a continuously scaled circular WSA aperture) in some embodiments. The layout can be optimized with respect to size as the antenna elements112are provided more densely near the center at118in some embodiments. In addition, the spacing between the antenna elements112associated with the layout can be changed to provide maximum density in some embodiments in some embodiments. A wavelength scale parameter can define the pattern for the array110and is indicative of a wavelength scale factor (e.g., a lattice relaxation factor) indicating relaxation of antenna spacing (or relaxation of antenna spacing constraints) in some embodiments. In some embodiments, the antenna elements112near the center118are configured for higher frequency radio frequency signals and the antenna elements112farther from the center118are configured for lower frequency RF signals. In some embodiments, the antenna elements112in the centermost region of the array110are configured to cover the entire operational bandwidth, the antenna elements112in the region next tom the centermost region are configured to operate in a sub band below the highest portion and above the lowest portion of the operational bandwidth, and the antenna elements112at the periphery are configured to operate at the lower portion of the operational bandwidth. The wavelength scale parameter can indicate a density of the antennas of each band of the antenna system100as a function of position. For example, at least two adjacent antenna elements112of a first band can be spaced from one another by a first value of the wavelength scale factor, where the first value corresponds to the second frequency. Similarly, at least two adjacent antenna elements112of a second band can be spaced from one another by a second value of the wavelength scale parameter, where the second value corresponds to the third frequency. As illustrated in the various electronically scanned arrays described herein, including the antenna system100, the spacing within bands can change in value from relatively inward bands to relatively outward bands. In some embodiments, the antenna elements112of each band have a half-wavelength spacing (e.g., the spacing amongst the antenna elements112of the first band is a half-wavelength, where the wavelength corresponds to the first frequency i.e. wavelength=c/first frequency, where c=speed of light).

The values of the wavelength scale parameter can correspond to the positions of the antenna elements112along with the frequency of the band. In a Cartesian coordinate system, the value of the wavelength scale parameter can be a function of frequency, element excitation, and/or element delay (or phase) for a particular antenna element112and can be a function of x, y, and frequency, where the antenna system100is configured as a planar array, and x- and y-refer to Cartesian coordinate dimensions. In a three-dimensional coordinate system, such as where the antenna system100is configured as a three-dimensional array—such as a conformal array configured to conform to a three-dimensional surface of an airborne platform or other platform—the value of the wavelength scale parameter can be a function of x, y, z, and frequency (or may be similarly determined in spherical or cylindrical coordinates as appropriate to the application). The wavelength scale parameter can be used to define a position of each antenna element112relative to a reference point, such as the center118of the antenna system100, or a peripheral point. The wave length scale parameter can be calculated and the corresponding pattern can be provided according to the principles of U.S. patent application Ser. No. 15/970,781, filed by West et al. on May 3, 2018, and U.S. patent application Ser. No. 16/021,784, filed Jun. 28, 2018, “Circularly Symmetric Tightly Coupled Dipole Array”, incorporated herein by reference in their entireties.

In some embodiments, the antenna elements112are arranged in concentric circles. Other elements and element patterns are appropriate for a circularly symmetric WSA. In some embodiments, the elements112are arranged as multi-arm reactively load spirals. In some embodiments, the antenna elements112are cross bowtie dipoles which are end chambered to fit around a given circumference. In some embodiments, the antenna elements112are any radiating element that intrinsically creates circular polarizations, for example, micro-strip patches or open ended quad ridged waveguides.

An antenna element230of appropriate size is used as each of the antenna elements112(e.g., elements114,124,134,144,154,164,174,184,194,204, and214) in some embodiments. The element230can be configured as an arched dual linear dipole (ADLD) radiating element in some embodiments. The element230includes a first dipole element232and a second dipole element234. The dipole element232is provided in a straight linear configuration, and the dipole element234is provided in a curved configuration in some embodiments. The dipole element234is provided along a circumference while the dipole element232is provided in a radial fashion with respect to the center118of the array110in some embodiments.

The antenna element230is provided on a printed circuit board in some embodiments. The dipole elements232and234are printed circuit board trace conductors in some embodiments. The antenna element230is provided using metal cutouts or other conductive structures in some embodiments. In some embodiments, the antenna element230is a slot type radiators or spiral type radiator. In some embodiments, the antenna elements112are provided on a single circuit board or on multiple circuit boards (e.g., tiles) that are joined together to form the antenna array110. In some embodiments, radially opposed symmetric ADLD element pairs can be generalized to other radiating element types.

The dipole elements232and234intersect or cross over each other at an end236at a 90 degree angle (e.g., a tangent line of dipole element234at the end236is perpendicular to the dipole element232) in some embodiments. The dipole element234is provided on a first layer of a circuit board and the dipole element232is provided on a second layer of the circuit board in some embodiments. In some embodiments, the dipole elements232and234intersect on a single layer of the circuit board. In some embodiments, the dipole element234is provided on the same circuit board level as the dipole element232but does not connect to the dipole element232.

In some embodiments, a capacitive region249is between the end236of the dipole element232and an end244of the dipole element234. The capacitive region249can include conductors associated with the elements232and234in an interdigitated configuration or printed circuit board structure in some embodiments. A dipole element similar to the dipole element234is disposed at or near an end246of the dipole element234, and a dipole element similar to the dipole element232is disposed at or near the end246.

The dipole element234is provided at a radius of curvature and is curved inwardly towards the center118in some embodiments. The distance from the dipole element234at the end244to the tangent line238is greater than the distance between the tangent line238at the midpoint and the dipole element234and the same as the distance between the tangent line238and the end246of the dipole element234(as shown by vectors) in some embodiments. In some embodiments, radius of curvature is the same as the radius of curvature of the circumference upon which the dipole element232is provided. In some embodiments, the radius of curvature is greater than or less than the radius of curvature of the circumference upon which the dipole element232is provided.

With reference toFIG. 2, an antenna system300includes an array310which is similar to the antenna array110(FIG. 1). The antenna system300includes arched radiating elements334similar to the dipole element234(FIG. 1). The arched radiating elements334are provided at different circumferences342and344. The antenna array310also includes linear radiating antenna elements332similar to the dipole elements232. The dipole elements332are radially disposed while the dipole elements334is bent or curved about a constant radius and disposed along one of the circumferences342and344. The constant radius is the radius of the circumferences342and344in which the dipole element334is disposed in some embodiments. The radiating elements332and334are disposed in a WSA arrangement with growth from the center of the array310and have balanced feeds in some embodiments.

The radiating antenna elements332and334provide a cross-linear dipole (e.g., element230) that is distorted to fit within the circular configuration of the antenna array310. In isolation, each pair of the radiating antenna elements332and334does not have pure dual orthogonal (DOLP) polarization. However, the array310advantageously utilizes parasitic cross-polarization cancellation properties to achieve dual orthogonal linear polarization for the entire array310in some embodiments. The cross polarization of diametrically opposed elements334(e.g., dipoles) cross cancels to realize pure linear polarization (although rotated) in some embodiments. The elements332have pure linear polarization (although rotated) in some embodiments. The resulting dipole pair characteristics of a pair of the elements332and334have a characteristic that is not orthogonal, phase coincident, and not necessarily the same resonant frequency in some embodiments. The techniques discussed below are utilized to provide an orthogonal characteristic, a phase coincident characteristic, and/or same resonant frequency.

The pairs338and339of the radiating antenna elements332and334are provided sequentially and rotated about the circumference342as opposing pairs in some embodiments. The pairs340and341of the radiating antenna elements332and334are provided sequentially and rotated about the circumference344as opposing pairs in some embodiments. The pairs338and339and the pairs340and341are 180° apart on the circumferences342and344, respectively, in some embodiments.

The radiating antenna elements332are capacitively coupled to the four neighboring radiation antenna elements332as represented by the capacitor schematic symbols365inFIG. 2. Capacitive coupling occurs between the neighboring radiating antenna elements332in different circumferences342and344and between the neighboring radiating antenna elements332in different radial positions in some embodiments. The array110is also has similarly capacitively coupled elements112(FIG. 1) in some embodiments.

With reference toFIG. 3, antenna elements380and382can be used as the antenna elements112(FIG. 1) or as the respective elements332and334in some embodiments. The antenna element382is an arched dipole element, and the antenna element380is a linear dipole element. The element380is provided on a radial axis407and has a length404. The length404is between a circumference406and a circumference408. The circumference408is for elements similar to the elements382sized for the location on the array110(FIG. 1) or310(FIG. 2) The element382is provided on a circumference406and has a length402. The length402is equal to the arc length which is equal to 2πR/360/deltaphi where R is the radius of the circumference406and deltaphi is the angle range covered by the element382. In some embodiments, the length402and404are set equal to each other and set according to a resonance frequency for the dipole elements corresponding to the position in the array110(FIG. 1) or310(FIG. 2).

Similar values for the capacitive coupling combined with a similar length for the lengths402and404provides a similar resonant frequency in some embodiments. In some embodiments, the arch lengths (e.g., the length402) of the elements382is adjusted to the length404of the elements380while maintaining WSA unit cell growth (as dictated by the wavelength scale factor) in some embodiments. In some embodiments, the capacitive coupling for the elements380and the elements382is adjusted to achieve the same resonance frequency. Capacitors or coupling capacitance associated the element380and the element382are different to compensate different lengths404and402in some embodiments.

With reference toFIG. 4, pairs of the antenna elements332and334are represented electrically as pairs of antenna elements332a-hand334a-h. The parasitic polarization components for the pairs of the antenna elements332a-hand334a-hare diametrically opposed so that they cancelled out to provide the vectors shown inFIG. 4in some embodiments. In some embodiments, the entire antenna systems100and300are provided with diametrically opposed pairs of antenna elements that provide parasitic cross-polarization as a function of phi (angular position) and radius as shown inFIG. 4. The pairs of the elements332a-hand334a-hcancel out parasitic cross-polarization and each pair collectively functions as rotated DLP cross-dipoles within a circular array of environment for a given radius. Each concentric ring used in the antenna system100or300can have the same effect. The non orthogonal characteristics of the antenna elements332a-hand334a-hare compensated by polarization synthesis to achieve dual orthogonal linear polarization in some embodiments.

The right-hand and left-hand circular polarization (RHCP/LHCP) for the antenna systems100and300(FIGS. 1 and 2) is achieved with an ultra-wideband 90° phase shift between the dipole elements (e.g., dipole element232and234or332a-hand334a-h) within the pair (e.g., the antenna element112) in some embodiments. The polarization rotation of each of the pairs of dipole elements can be configured a priori to provide relatively true dual orthogonal linear polarization pairs. For example, the pair of antenna elements232and234can be rotated by electronic adjustment to have vertical and horizontal polarization orientations. Polarization synthesis networks (PSN) at each pair can be used to generate arbitrary polarization at the radiating element and phase center alignment of the pairs of dipole element232and234or332a-hand334a-has discussed below in some embodiments.

With reference toFIG. 5, a polarization synthesis network304is utilized with the array110or310and is coupled to antenna elements502aand502band504aand504bwhich represent differential inputs or outputs for antenna elements332aand334a(FIG. 4), respectively. The antenna elements502a-band504a-bcan be single ended input port elements in some embodiments. The polarization synthesis network304is similarly coupled to the antenna elements332b-hand the antenna elements334b-h(FIG. 4). The polarization synthesis network304includes a variable gain amplifier505, a variable gain amplifier507, a phase shifter506, a phase shifter508, a polarization alignment time delay unit516, a polarization alignment time delay unit518, and a combiner530. The polarization synthesis network304can be provided in the feed for the antenna arrays110and310in some embodiments. In some embodiments, the polarization alignment time delay unit516and the polarization alignment time delay unit518are optional. In some embodiments, the polarization synthesis network304uses the techniques described in U.S. application Ser. No. 16/146,349, filed on Sep. 28, 2018.

A digital control circuit534provides control signals to the variable gain amplifier505, variable gain amplifier508, phase shifter506, and phase shifter508to provide appropriate adjustment to the polarization associated with the antenna elements502a-band504a-b. The combiner530combines the signals from the polarization alignment time delay unit516and a polarization alignment time delay unit518associated with the signals from the pair of elements502a-band the pair of the antenna elements504a-b. Arbitrary adjustments as well as adjustments to provide horizontally and vertically polarized signals at the combiner530can be achieved. Elliptical polarization, circular polarization and orthogonal polarization can be provided using the polarization synthesis network304in some embodiments.

The variable gain amplifiers505and507respectively provide selected amplification for the signals of the antenna elements502a-band the signals of the antenna elements504a-b. The phase shifters506and508, respectively, provide selected phase shifting for the signals of the antenna elements502a-band the signals of the antenna elements504a-b. The polarization alignment time delay unit516and the polarization alignment time delay unit518respectively provide selected time delays for the signals of the antenna elements502a-band the signals of the antenna elements334a-b. The polarization alignment time delay unit516and the polarization alignment time delay unit518allow adjustment (e.g., coarse over 360 degrees or fine) of phase shift to be made for the signals of the antenna elements502a-band the signals of the antenna elements504a-bin some embodiments. In some embodiments, the polarization alignment time delay unit516and the polarization alignment time delay unit518provide phase center adjustment to provide aligned phase centers for the antenna elements502a-band the signals of the antenna elements504a-b.

The digital control circuit534provides control signals to the variable gain amplifier507, variable gain amplifier505, phase shifter506, phase shifter508, polarization alignment time delay unit516, and the polarization alignment time delay unit518to make the adjustments in accordance with the geometry associated with the layout of the pairs of the antenna elements332a-hand334a-h(FIG. 4) to provide orthogonally polarized signals in some embodiments. The digital control circuit534configures the polarization synthesis network304coupled to provide a dual orthogonal linear pair response for non-orthogonal dipole pairs of the array110or310in some embodiments. The digital control circuit534provides control signals for the polarization alignment time delay unit516and the polarization alignment time delay unit518according to phase center time delay processing to align the phase centers in some embodiments. The techniques described in U.S. patent application Ser. No. 15/955,030, entitled, “Systems and Methods for Phase-Coincidental Dual Polarized Wideband Antenna Arrays,” incorporated herein by reference in its entirety, “can be utilized to provide phase coincidence in some embodiments. The control signals can be provided as a function of beam steering angle and frequency.

It will be appreciated that the various ESAs described herein, including the antenna system100, may include varying arrangements of antennas (e.g., two-by-two; three-by-four; the second band may include multiple adjacent arrays. In some embodiments, providing the array of antennas includes providing a first circular array corresponding to the first design frequency and a second circular array corresponding to the second design frequency. At least a subset of antennas of the second circular array surrounds the first circular array. In some embodiments, the arrays of antennas are provided to form a three-dimensional array, which can be made conformal to a three-dimensional surface, such as a surface of an airborne platform.

The construction and arrangement of the systems and methods as shown in the various exemplary embodiments are illustrative only. Other numbers or types of antenna elements, other polarization configurations and other numbers or types dipole elements can be used. Although only a number of embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, orientations, etc.). For example, the position of elements may be reversed, flipped, or otherwise varied and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are included within the scope of the inventive concepts disclosed herein. The order or sequence of any operational flow or method operations may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the inventive concepts disclosed herein.