Systems and methods for phase-coincidential dual-polarized wideband antenna arrays

The antenna includes a substrate and a plurality of unit cells coupled to the substrate. Each unit cell includes a dipole feed extending from the substrate, a first antenna dipole coupled to the dipole feed, and a second antenna dipole coupled to the dipole feed. The first antenna dipole includes a first arm on a first side of the dipole feed and a second arm on a second side of the dipole feed opposite the first side. The second antenna dipole includes a third arm on a third side of the dipole feed and a fourth arm on a fourth side of the dipole feed opposite the third side.

BACKGROUND

The inventive concepts disclosed herein relate generally to the field of antenna arrays. More particularly, embodiments of the inventive concepts disclosed herein relates to systems and methods for phase-coincidental dual-polarized wideband antenna arrays.

Existing wide band arrays typically use a printed circuit board (e.g., card-based) design. Antenna elements are printed on a card printed circuit board, which is inserted vertically into a ground plane. For example, Vivaldi arrays, Balanced Antipodal Vivaldi Array (BAVA), and tightly-coupled dipole arrays (TCDA) may be implemented in such a manner. The card-based assembly can be a significant determinant of the cost of such arrays.

Dual polarization in antenna arrays can enable polarization diversity. In existing arrays, vertical, horizontal, and circular polarized waves can be supported. Such functionality can be necessary for electronic warfare and covert intelligence gathering by electronic means applications.

In existing dual polarization implementations, the cards are oriented orthogonal to one another, such as into an egg crate assembly. As such, the antenna feeds for each unit cell are displaced from a geometric center of each cell. For example,FIG. 1illustrates existing system100a, where antenna feeds105aare located in the middle of edges of each unit cell, such that the antenna element is center-fed and displaced from the geometric center110a.FIG. 1also illustrates existing system100b, where antenna feeds105bare located at corners of edges of each unit cell, such that the unit cell is edge fed and thus offset relative to the antenna feeds105b. Various such implementations can have high size, weight, power, and cost (SWAP-C) considerations, and can require complex polarization synthesis networks to account for the offsets between feed locations and to synthesize circular polarization.

SUMMARY

In one aspect, the inventive concepts disclosed herein are directed to an antenna including a substrate and a plurality of unit cells coupled to the substrate. Each unit cell defines a center and includes a first antenna dipole and a second antenna dipole. The first antenna dipole includes a first arm on a first side of the center and a second arm on a second side of the center opposite the first arm. The first arm includes a first arm end adjacent to the center and configured to receive a first voltage. The second arm includes a second arm end adjacent to the center and configured to receive a second voltage. The second antenna dipole includes a third arm on a third side of the center and a fourth arm on a fourth side of the center opposite the third side. The third arm includes a third arm end adjacent to the center and configured to receive a third voltage. The fourth arm includes a fourth arm end adjacent to the center and configured to receive a fourth voltage.

In a further aspect, the inventive concepts disclosed herein are directed to a method of manufacturing an antenna. The method includes providing a substrate; printing a first arm of a first antenna dipole of a unit cell on the substrate, the unit cell defining a center, the first arm having a first arm end adjacent to the center; printing a second arm of the first antenna dipole on the substrate on an opposite side of the center from the first arm, the second arm having a second arm adjacent to the center; printing a third arm of a second antenna dipole of the unit cell on the substrate, the third arm having a third arm end adjacent to the center; and printing a fourth arm of the second antenna dipole on the substrate on an opposite side of the center from the third arm, the fourth arm having a fourth arm end adjacent to the center.

DETAILED DESCRIPTION

Broadly, embodiments of the inventive concepts disclosed herein are directed to an antenna. The antenna includes a substrate and a plurality of unit cells coupled to the substrate. Each unit cell defines a center and includes a first antenna dipole and a second antenna dipole. The first antenna dipole includes a first arm on a first side of the center and a second arm on a second side of the center opposite the first arm. The first arm includes a first arm end adjacent to the center and configured to receive a first voltage. The second arm includes a second arm end adjacent to the center and configured to receive a second voltage. The second antenna dipole includes a third arm on a third side of the center and a fourth arm on a fourth side of the center opposite the third side. The third arm includes a third arm end adjacent to the center and configured to receive a third voltage. The fourth arm includes a fourth arm end adjacent to the center and configured to receive a fourth voltage.

The antenna can be a wideband array antenna, where the substrate is a circuit board, and the antenna dipoles are printed on a planar surface of the circuit board. The antenna dipoles can be center-fed and arranged in an orthogonal arrangement to enable dual polarization and phase coincidence. The antenna can have reduced SWAP-C as compared to existing systems; for example, the antenna can have a 50 percent height reduction as compared to existing BAVA systems. As compared to existing systems for card based arrays with offset feeds, an antenna manufactured in accordance with the inventive concepts disclosed herein can enable desired features, such as dual polarization and phase coincidence, without relying on complex polarization synthesis networks. The antenna can be used in a variety of implementations, including but not limited to portable electronic devices, airborne platforms, and ground platforms.

Referring now toFIG. 2, an embodiment of a wideband array200according to the inventive concepts disclosed herein includes a plurality of unit cells205coupled to a substrate210. The plurality of unit cells205are used to receive and transmit radio frequency signals at desired frequencies, and can be configured for wideband operation. The plurality of unit cells205can be differentially fed voltages corresponding to desired radio frequency signals at a center of each unit cell to enable dual polarization and phase coincidence.

In some embodiments, the plurality of unit cells205are configured to transmit a radio frequency signal over a bandwidth extending from and including a first frequency to (and including) a second frequency. The plurality of unit cells205can be configured for wideband operation such that a ratio of the second frequency to the first frequency is at least two to one. In some embodiments, the first frequency is approximately 3 GHz (e.g., 3 GHz+/−100 MHz), and the second frequency is approximately 18 GHz (e.g., 18 GHz+/−100 MHz).

The plurality of unit cells205can be attached to and extending from the substrate210. The plurality of unit cells205can extend orthogonal to the substrate210. In some embodiments, the plurality of unit cells205are sized to reduce SWAP-C of the wideband array200as compared to existing systems. A height by which the plurality of unit cells205extend from the substrate210may be no greater than 0.5 times a wavelength of the radio frequency signal to be transmitted by the plurality of unit cells205at the highest frequency. For example, wherein the wideband array200is configured to operate from approximately 3 GHz to 18 GHz, the plurality of unit cells205can be sized such that the wideband array200has a height no greater than 0.2,″ providing a height reduction of at least 50% as compared to existing BAVA systems.

The substrate210is a circuit board, in some embodiments. The plurality of unit cells205can be printed on the substrate210. In some embodiments, the substrate210is made from a composite and/or laminate material. For example, the substrate210can be made from an epoxy laminate, such as FR-4 laminate. The substrate210can define a planar surface on which the unit cells205are attached.

Referring now toFIG. 3, an embodiment of the plurality of unit cells205ofFIG. 2is shown according to the inventive concepts disclosed herein. Each unit cell205defines a center305and includes a first antenna dipole310and a second antenna dipole320. The center305can be defined as a geometrical center of the unit cell205; as an axis orthogonal to the substrate210, substantially equidistant from each of the antenna dipoles310,320, and in between the antenna dipoles310,320; and/or a point on the axis.

The first antenna dipole310includes a first arm311on a first side of the center305and a second arm312on a second side of the center305opposite the first side. The first arm311and second arm312are orthogonal to the substrate210, and can extend from the center305in parallel and opposite directions.

Similarly, the second antenna dipole320includes a third arm321on a third side of the center305and a fourth arm322on a fourth side of the center305opposite the third side. The third arm321and fourth arm322are also orthogonal to the substrate210, and can extend from the center305in parallel and opposite directions. As compared to existing systems, such as shown inFIG. 1, each unit cell205is fed (e.g., receives) voltages differentially from the center305of the unit cell205so that there is no offset from the center305of the unit cell205.

As shown inFIG. 3, the first arm311can be orthogonal to the third arm321and fourth arm322, such that a 90 degree angle is formed between the first arm311and each of the third and fourth arms321,322in a plane parallel to the substrate210. Similarly, the second arm312is orthogonal to the third arm321and fourth arm322. The arms of each unit cell205may be spaced from adjacent arms of adjacent unit cells205.

Referring now toFIG. 4, an embodiment of a unit cell400is shown in greater detail according to the inventive concepts disclosed herein. The unit cell400can incorporate features of the unit cell205described with reference toFIGS. 2-3. The unit cell400defines a center405, and includes a first antenna dipole410including a first arm411and a second arm412, and a second antenna dipole420including a third arm421and a fourth arm422.

The first arm411includes a first arm end413adjacent to the center405, at which the first arm411receives (e.g., can be fed) a first voltage. The second arm412includes a second arm end414adjacent to the center405, at which the second arm412receives a second voltage. Similarly, the third arm421includes a third arm end423adjacent to the center405, at which the third arm receives a third voltage, and the fourth arm422includes a fourth arm end424adjacent to the center405, at which the fourth arm receives a fourth voltage. As such, the unit cell400can be center-fed.

In some embodiments, the antenna dipoles410,420are configured to emit radiation with phase coincidence. For example, each antenna dipole410,420can define a respective first or second phase center, the respective phase center representing an apparent point at which radiation from the antenna dipole410,420is emitted. The first phase center can coincide with the second phase center such that the unit cell405has phase coincidence. For example, the first phase center and second phase center can be identical points in space.

As shown inFIG. 4, the first antenna dipole410and second antenna dipole420can each be linearly polarized, enabling the unit cell400to be circularly polarized. In some embodiments, the first arm411can receive the first voltage at a phase of zero degrees (or a baseline phase), the second arm412can receive the second voltage at a phase of 180 degrees, the third arm421can receive the third voltage at a phase of zero degrees, and a fourth arm422can receive the fourth voltage at a phase of 180 degrees. Radio frequency signals and/or electric fields generated by the arms of the antenna dipoles410,420can have corresponding phases.

Referring now toFIG. 5, a chart500illustrates performance of a wideband array (e.g., wideband array200) configured in accordance with embodiments of the inventive concepts disclosed herein. Chart500illustrates isolation, based on S-parameters, between horizontally polarized and vertically polarized dipole arms, indicating that the isolation can be at least 40 dB broadside from zenith across the frequency band from 3 GHz to 18 GHz. In some embodiments, the isolation can be at least 75 dB.

Referring now toFIG. 6, a side sectional view of a wideband array600is shown according to an embodiment of the inventive concepts disclosed herein. The wideband array600can incorporate features of the wideband array200and unit cells205,400as described herein. In some embodiments, the wideband array600includes a plurality of unit cells605, a substrate layer610, and an aperture layer615. In some embodiments, the TCDA600includes a plurality of spacers620between the unit cells605and the substrate layer610and aperture layer615. For example, the spacers620can be ball grid array spacers. The performance of the wideband array600(e.g., as described above with respect toFIG. 5) can be similar or identical with our without the spacers620.

In some embodiments, the TCDA600defines a height625. The TCDA600can be sized such that the height625is less than existing systems. For example, where the TCDA600is configured to operate across a frequency band from approximately 3 GHz to 18 GHz, the height625may be 0.2 inches, which can provide a height reduction of at least 50% as compared to existing BAVA systems which may be manufactured to provide similar operating ranges. The height625may be a function of a height630of the unit cells605(e.g., height of dipole feed and/or antenna dipoles of the unit cell; height by which dipole feed and/or antenna dipoles of the unit cell extend from substrate610). In some embodiments, the height630is no greater than 0.5 times a wavelength of the radio frequency signal to be transmitted by the plurality of unit cells605at the highest frequency.

Referring now toFIG. 7, an exemplary embodiment of a method700for manufacturing a phase-coincident dual-polarized wideband antenna array according to the inventive concepts disclosed herein may include one or more of the following steps.

A step (705) may include providing a substrate. The substrate can be a circuit board. In some embodiments, the substrate is made from a composite and/or laminate material. For example, the substrate can be made from an epoxy laminate, such as FR-4 laminate.

A step (710) may include printing a first arm of a first antenna dipole of a unit cell on the substrate. For example, where the substrate is a circuit board, the first arm can be printed on the substrate. The unit cell defines a center. The first arm has a first arm end adjacent to the center. The first arm can be printed on the substrate to extend orthogonal to the substrate. The first arm can receive a first voltage at the first arm end.

A step (715) may include printing a second arm of the first antenna dipole on the substrate on an opposite side of the center from the first arm. Similar to the first arm, the second arm can be printed on the substrate where the substrate is a circuit board, and can extend orthogonal to the substrate. The second arm has a second arm end adjacent to the center. The second arm can receive a second voltage (which may be out of phase from the first voltage by 180 degrees) at the second arm end.

A step (720) may include printing a third arm of a second antenna dipole of the unit cell to the substrate. The third arm can be printed on the substrate where the substrate is a circuit board, and can be printed to the substrate to extend orthogonal to the substrate. The third arm can be orthogonal to the first and second arms (e.g., spaced 90 degrees from each of the first and second arms in a plane parallel to the substrate). The third arm includes a third arm end adjacent to the center, and can receive a third voltage at the third arm end. The third voltage can be of the same phase as the first voltage.

A step (725) may include printing a fourth arm of the second antenna dipole to the substrate on an opposite side of the center from the third arm. Similar to the third arm, the fourth arm can be printed on the substrate where the substrate is a circuit board, and can be orthogonal to the substrate. The fourth arm can be orthogonal to the first and second arms (e.g., spaced 90 degrees from each of the first and second arms in a plane parallel to the substrate). The fourth arm includes a fourth arm end adjacent to the center, and can receive a fourth voltage at the fourth arm end. The fourth voltage can be of the same phase as the second voltage (e.g., 180 degrees out of phase from the first and third voltages).

As will be appreciated from the above, antennas/antenna arrays according to embodiments of the inventive concepts disclosed herein may have reduced SWAP-C as compared to existing systems, while enabling dual polarization and phase coincidence, by feeding antenna dipoles from the geometric center of unit cells. The antennas/antenna arrays can have isolation between horizontal and vertical polarization of at least 40 dB at broadside for the full operational bandwidth and, in some embodiments, at least 75 dB.