Patent Application
20150295309
Embodiments of the present disclosure generally relate to antenna assemblies, and, more particularly, to configurable phased-array antenna assemblies that may be switched between a plurality of antenna personalities.
Microwave antennas may be used in various applications, such as satellite reception, remote sensing, military communication, and the like. Printed circuit antennas generally provide low-cost, light-weight, low-profile structures that are relatively easy to mass produce. These antennas may be designed in arrays and used for radio frequency systems, such as identification of friend/foe (IFF) systems, radar, electronic warfare systems, signals intelligence systems, line-of-sight communication systems, satellite communication systems, and the like.
One known antenna assembly provides a static antenna assembly that is incapable of scanning beyond 45° from normal to the antenna face while maintaining an ultrawide bandwidth ratio of 6:1 or more. Further, spiral antennas are typically too large for many practical applications and are incapable of providing polarization diversity. Another known antenna assembly provides a bandwidth ratio of 9:1 but generally exhibits an undesirably large voltage standing wave ratio (VSWR) when scanned beyond 50° from normal to the antenna face. Further, connected arrays over a ground plane have similar scan and VSWR limitations. Additionally, fragmented antenna arrays typically include small features that may not be scaled to high radio frequencies, may also be limited to small scan volumes, and may be inefficient.
In general, static designs they may be able to support one system function but typically cannot be used for multiple functions. Narrow band antennas are typically designed to support only one specific RF system and cannot be interchanged to support other system and frequencies out with great difficulty. Known static antenna wideband designs and assemblies typically do not provide a compact design having an instantaneous bandwidth of at least 6:1, wide field of view or scan capability up to 60° or more from normal to antenna face, and arbitrary current control that provides both selective bandwidth and polarization diversity capability.
Certain embodiments of the present disclosure provide an antenna unit-cell phased array assembly that may include a first ground plane, a second ground plane that may be switched between grounding and non-grounding states, and an antenna array that may include first and second antenna layers. Each of the first and second antenna layers may include a plurality of pixels (or similar features) interconnected by a plurality of first phase change material (PCM) switches. The first PCM switches are configured to be selectively switched between phases to provide a plurality of antenna patterns within the first and second antenna layers. The first PCM switches are configured to be selectively switched to provide multiple antenna personalities.
The second ground plane may include a plurality of plates interconnected by a plurality of second PCM switches. The second PCM switches are selectively activated and deactivated to switch the second ground plane between the grounding and non-grounding states.
The antenna assembly may also include a plurality of control lines that connect the first ground plane to the second ground plane and the first and second antenna layers. For example, the first PCM switches may connect to the plurality of control lines.
The antenna assembly may also include a feed post mounted to the first ground plane. The second ground plane may secure to a portion of the feed post. The feed post may include one or more conductors that connect to the first and second antenna layers.
The antenna assembly may also include a first control grid connected to the first antenna layer, and a second control grid connected to the second antenna layer. Each of the first and second control grids may include a first set of traces that intersect with a second set of traces at a plurality of intersections that operatively connect to a respective one of the first PCM switches. Each of the intersections may be energized to switch each of the first PCM switches between phases. The first and second control grids may be configured to be frequency selective. Each of the first and second control grids may also include one or more inductors inserted at sub-wavelength intervals.
Each of the first PCM switches may be formed of Germanium Tellurium (GeTe) having first and second phases. One of the first and second phases is electrically conductive, and the other of the first and second phases is non-conductive.
Certain embodiments of the present disclosure provide an antenna assembly that may include an antenna array including at least one antenna layer. The antenna layer(s) may include a plurality of pixels interconnected by a plurality of first phase change material (PCM) switches. The first PCM switches are configured to be selectively switched between phases to provide a plurality of antenna patterns within the antenna array to provide multiple antenna personalities. In at least one embodiment, the at least one antenna layer includes at least two antenna layers. The antenna assembly may also include one or more switched ground planes that may be switched between grounding and non-grounding states.
The foregoing summary, as well as the following detailed description of certain embodiments will be better understood when read in conjunction with the appended drawings. As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of the elements or steps, unless such exclusion is explicitly stated. Further, references to “one embodiment” are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising” or “having” an element or a plurality of elements having a particular property may include additional elements not having that property.
An antenna array 16 is operatively connected to the feed post above the switched ground plane 14. The antenna array 16 may include first and second antenna layers 18 and 20 separated by a circuit board, for example. Alternatively, the antenna array 16 may include more than two antenna layers. Also, alternatively, the antenna array 16 may include only one antenna layer. Each antenna layer 18 and 20 may include a plurality of antenna pixels 22 connected to other antenna pixels 22 through switches, which may be formed of a phase change material, as described below.
A matching layer 26 may be positioned over the antenna array 16. The matching layer 26 is configured to match the antenna array 16 to free space or air. The matching layer 26 may be or include a radome, for example, which may be formed of a dielectric material. The radome provides a structural, weatherproof enclosure that protects the antenna array 16, and may be formed of material that minimally attenuates the electromagnetic signal transmitted or received by the antenna array 16. As shown, the matching layer 26 may be formed as a block, which may include drilled cylindrical or semi-cylindrical holes to form inwardly-curved corners that are configured to control undesired surface waves. However, the matching layer 26 may be various other shapes and sizes, such as a pyramid, sphere, or the like. Further, the matching layer may be formed from multiple materials. In at least one embodiment, the matching layer 26 may not include the inwardly-curved corners. The drilled holes may be formed using other shapes and sizes, such as rectangular, triangular, spherical, or the like. The drilled holes may be placed in different locations other than the corners and be formed by multiple holes and shapes. Alternatively, the antenna assembly 10 may not include the matching layer 26.
As shown, a plurality of control lines 28 extend upwardly from the ground plane 12, around the outer boundary of the switched ground plane 14, and around the outer boundary of the antenna array 16. The control lines 28 may form a lattice around the antenna assembly 10. The control lines 28 may be conductive metal traces that are configured to allow electrical signals to pass therethrough. The control lines 28 are configured to relay signals that switch the various switches within the antenna assembly between on and off positions (such as between conductive and non-conductive states of a phase change material switch) in order to switch the antenna assembly 10 between various antenna patterns.
Different antenna patterns may provide different antenna personalities. Each antenna personality may be defined as a unique combination of frequency, bandwidth, polarization, power level, scan angle, geometry, beam characteristics (width, scan rate, and the like), and the like.
The antenna assembly 10 may be operatively connected to a control unit 30. For example, the control unit 30 may be electrically connected to the control lines 28. The control unit 30 is configured to control switching between the plurality of antenna patterns, for example. The control unit 30 may be or otherwise include one or more computing devices, such as standard computer hardware (for example, processors, circuitry, memory, and the like). The control unit 30 may be operatively connected to the antenna assembly 10, such as through a cable or wireless connection. Optionally, the control unit 30 may be an integral component of the antenna assembly 10. Alternatively, the antenna assembly 10 may not include a separate and distinct control unit.
The control unit 30 may include any suitable computer-readable media used for data storage. For example, the control unit 30 may include computer-readable media. The computer-readable media are configured to store information that may be interpreted by the control unit 30. The information may be data or may take the form of computer-executable instructions, such as software applications, that cause a microprocessor or other such control unit within the control unit 30 to perform certain functions and/or computer-implemented methods. The computer-readable media may include computer storage media and communication media. The computer storage media may include volatile and non-volatile media, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or other data. The computer storage media may include, but are not limited to, RAM, ROM, EPROM, EEPROM, flash memory or other solid state memory technology, CD-ROM, DVD, or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which may be used to store desired information and that may be accessed by components of the control unit 30.
As shown, the end 39 of each plate 36 is connected to an end 39 of a neighboring plate 36 by a switch 38. Similarly, the side 40 of each plate 36 is connected to a side 40 of a neighboring plate 36 by a switch 38. Further, switches 38 extend from outer ends 39 and outer sides 40 of the plates 36 at the periphery or outer unit-cell boundary of the switched ground plate 14. The switches 38 at the periphery of the switched ground plate 14 may connect to respective control lines 28 (shown in
Each switch 38 may be formed of a phase change material (PCM), such as Germanium Tellurium (GeTe). A PCM melts and solidifies at distinct temperatures. Heat is absorbed or released when the PCM changes from solid to liquid, and vice versa. PCM switches do not require static bias for operation. Instead, power need only be applied during switching to switch the PCM switch between phases. One of the phases may be electrically conductive, while the other state may be non-conductive. In general, PCM switches have two stable states that differ in electrical conductivity by several orders of magnitude. Switching may be accomplished through controlled heating and cooling of the PCM switches.
Referring to
The switched ground plane 14 may be configured to tune the antenna assembly 10 to improve the high frequency behavior of the antenna assembly 10. The switched ground plane 14 may be switched on and off to selectively provide narrow and high band reception, for example. If all of the switches 38 are activated (for example, switched on, such as through phase change when power is applied during a switching operation), the switched ground plane 14 acts a solid sheet of metal. If, however, all of the switches 38 are deactivated, the switched ground plane 14 simply provides a grid of plates, so that it is in a non-grounding state and not significantly electrically present. Alternatively, the plates 36 may be created using non-metallic, resistive, or the like surface materials. Optionally, a portion of the switches 38 may be activated, while a remaining portion of the switches 38 may be deactivated.
As shown, the switched ground plane 14 is separated from the ground plane 12 by a distance A. As such, when the switched ground plane 14 is activated, such as by the switches 38 changing phase, the effective ground plane to the antenna array 16 is moved up the distance A.
As noted above, the antenna array 16 may include an upper antenna layer 18 and a lower antenna array 20. The antenna layers 18 and 20 may be separated from one another by a circuit board 48 having a thickness B. As such, the antenna layers 18 and 20 are offset from one another by the distance B. The antenna pixels 22 of each antenna layer 18 and 20 may be interconnected by switches 50, such as PCM switches. Alternatively, the switches 50 may be other types of RF switches, such as MEMS, pin-diode, or the like.
The antenna layer 60 includes a plurality of pixels 64 interconnected by switches 66, similar to the plates of the switched ground plane 14 described above. The pixels 64 may be similar in size, shape, and distribution. Alternatively, the pixels 64 may be non-uniform in size, shape, and/or distribution. The switches 66 may be formed of a PCM, such as GeTe. The switches 66′ may be at the outer boundary of the antenna layer 60. The switches 66′ may extend past the unit cell boundary of the antenna layer 60 to provide connectivity to an adjacent unit-cell antenna assembly. The switches 66, including the switches 66′, may be selectively activated (for example, switched to a conductive state) and deactivated (for example, switched to a non-conductive state) through control and power signals received through the control lines 28 and/or the central conductors 45 by way of the transition members 52. The switches 66 may be activated or deactivated to form a desired antenna pattern of antenna pixels. For example, all of the switches 66 may be activated to form an antenna pattern of pixels in the shape of the antenna layer 60. Certain switches 66 may be deactivated to form an antenna pattern having a different shape.
Referring to
Referring to FIGS. 1 and 6-9, through the use of two antenna layers 18 and 20, overlapping regions of the two antenna layers may form parallel plate capacitors. At certain frequencies, the ground plane 12 may act as an inductor. Inductance is countered with capacitance. The capacitance of the antenna assembly 10 may be increased by the overlapping antenna layers 18 and 20, thereby reducing the inductance. As noted, the antenna assembly 10 may optionally include more than two antenna layers.
The control grid 80 includes a first set of parallel traces 82 and a second set of parallel traces 84 that are perpendicular to the first set of parallel traces 82. The parallel traces 82 intersect the parallel traces 84 at intersections 86. Each intersection 86 may abut into, or be otherwise proximate to, a switch within an antenna layer. For example, each switch may be associated with a respective intersection 86. The number and spacing of the traces 82 and 84 may correspond to the number of switches within a particular antenna layer, so that each switch may be associated with a distinct intersection 86.
As shown in
The control grid 80 may provide control signals using frequency selective control lines. A frequency selective control line may be formed by inserting inductors at sub-wavelength intervals therein. The inductors may be sized to have low impedance at switch control frequencies (such as around 20 MHz), and high impedance at operational frequencies (such as between 2-12 GHz). At low frequencies, the control path, such as the path 88, provides a continuous conductive trace. At high frequencies, the path provides a broken set of sub-wavelength floating metal patches, which are invisible to a high frequency, radiating wave. In this manner, the path may be activated at low frequencies and disconnected at high frequencies so as not to interfere with operation of the antenna assembly.
As noted above, the switches may be PCM switches. As such, the control grid 80 may operate to supply power to the intersections 86 to address particular switches to switch them on or off. The PCM switches do not require static bias for operation. PCM switches have two stable states that differ in electrical conductivity by several orders of magnitude. Switching may be accomplished through controlled heating and cooling of the PCM switches. The switch associated with the intersection 86′ is the addressed element that undergoes a state change. The switches may be sequentially changed to different states to form an antenna pattern.
A control grid, such as the control grid 80, may also be positioned underneath, above, or within the switched ground plane 14 (shown in
As shown, an antenna array 96 may not include a central void or aperture. Any of the antenna layers described above may include central pixels without a central void formed therethrough or therebetween.
Referring to
The antenna assembly may be reconfigured to provide RF performance personalities at narrow bandwidths (for example, 100 MHz), with the ability to scan at angles such as 45°, 60°, and the like. It has been found that the reconfigurable nature of the antenna assembly allows for operation at ultrawide bandwidth (for example, a 6:1 bandwidth ratio), or adjacent smaller band tunes as narrow as 100 MHz. The antenna assembly may be reconfigured to provide multiple personalities between first antenna pattern(s) configured for wideband operation, and second antenna pattern(s) configured for narrowband operation.
As described above, the antenna assembly may include two antenna layers, such as the antenna layers 18 and 20, which may be used to form, for example, a connected dipole array with capacitive dipole-like feeds underneath the connected antenna layers. The connected pixel and feed layers may be created using dual layer circuit boards, for example. The circuit board may be placed over a ground plane with foam dielectric layers below and above. A differential feed from the lower dipole-like feed may be capacitively coupled to a connected dipole element layer.
Each antenna layer may include a plurality of pixels. The pixels allow for multiple personalities by creating antenna patterns of varying shapes and sizes that may be used to tune the antenna assembly to specific frequencies, polarizations, and scan angles. The pixels may be interconnected using RF-compliant switches, which may be formed of phase change materials. The command and control of the switches may be achieved through use of addressed line schemes, such as those used in high density phase change memory systems.
It has been found that embodiments of the present disclosure provide antenna assemblies that may allow for wideband instantaneous bandwidth. The antenna assemblies may be switched to a narrow fractional bandwidth (such as 100 MHz) to provide better RF performance than is possible at a wideband tuning.
Embodiments of the present disclosure provide antenna assemblies in which on/off states of the connections, such as the switches, between the pixels, may be selectively activated and deactivated to provide a wide variety of antenna patterns. The different antenna patterns may be used for a variety of reasons, such as different missions, operational scenarios, and scan or field of view capabilities that are generally not possible with static array assemblies.
Embodiments of the present disclosure may be used with a multifunction and/or shared antenna configuration for communications, electronic warfare, RADAR and SIGNIT applications, for example. Embodiments of the present disclosure provide wide bandwidth coverage and polarization diversity to allow the transmission and reception of signals with any polarization that includes, but is not limited to, linear, circular, and slant polarized signals.
Certain embodiments of the present disclosure provide antenna assemblies that may include PCM switches, frequency selective control lines, and pixelated antenna layers. The antenna assemblies may be selectively configured between a plurality of antenna patterns.
Embodiments of the present disclosure provide antenna assemblies that may exhibit multiple antenna personalities. Each antenna personality may be a unique combination of frequency, bandwidth, polarization, power level, scan angle, geometry, beam characteristics (width, scan rate, and the like), and the like.
While various spatial and directional terms, such as top, bottom, lower, mid, lateral, horizontal, vertical, front and the like may be used to describe embodiments of the present disclosure, it is understood that such terms are merely used with respect to the orientations shown in the drawings. The orientations may be inverted, rotated, or otherwise changed, such that an upper portion is a lower portion, and vice versa, horizontal becomes vertical, and the like.
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments of the disclosure without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments of the disclosure, the embodiments are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.
This written description uses examples to disclose the various embodiments of the disclosure, including the best mode, and also to enable any person skilled in the art to practice the various embodiments of the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the various embodiments of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if the examples have structural elements that do not differ from the literal language of the claims, or if the examples include equivalent structural elements with insubstantial differences from the literal languages of the claims.
