Patent ID: 12206173

DETAILED DESCRIPTION

Before explaining various embodiments of the inventive concepts disclosed herein in detail, it is to be understood that the inventive concepts are not limited in their application to the arrangement of the components or steps or methodologies set forth in the following description or illustrated in the drawings. In the following detailed description of embodiments of the instant inventive concepts, numerous specific details are set forth in order to provide a more thorough understanding of the inventive concepts. However, it will be apparent to one of ordinary skill in the art having the benefit of the instant disclosure that the inventive concepts disclosed herein may be practiced without these specific details. In other instances, well-known features may not be described in detail to avoid unnecessarily complicating the instant disclosure. The inventive concepts disclosed herein are capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

As used herein a letter following a reference numeral is intended to reference an embodiment of a feature or element that may be similar, but not necessarily identical, to a previously described element or feature bearing the same reference numeral (e.g., 1, 1a, 1b). Such shorthand notations are used for purposes of convenience only, and should not be construed to limit the inventive concepts disclosed herein in any way unless expressly stated to the contrary.

Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by anyone of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

In addition, use of “a” or “an” are employed to describe elements and components of embodiments of the instant inventive concepts. This is done merely for convenience and to give a general sense of the inventive concepts, and “a” and “an” are intended to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

Also, while various components may be depicted as being connected directly, direct connection is not a requirement. Components may be in data communication with intervening components that are not illustrated or described.

Finally, as used herein any reference to “one embodiment,” or “some embodiments” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the inventive concepts disclosed herein. The appearances of the phrase “in at least one embodiment” in the specification does not necessarily refer to the same embodiment. Embodiments of the inventive concepts disclosed may include one or more of the features expressly described or inherently present herein, or any combination or sub-combination of two or more such features.

Broadly, embodiments of the inventive concepts disclosed herein are directed to an antenna array having multiple pillbox antenna structures arrange in a circle to cover the horizon. Each pillbox antenna structures includes a reflector configured to widen the resulting beam so that neighboring pillbox antenna structures produce beams that interact to more fully cover the horizon. In one embodiment all antennas are turned on simultaneously to act as an omni directional antenna. In the other case, each pillbox antenna is turned on individually to switch beam pointing angles. A feed layer may include transmit/receive modules that are configured to apply amplitude and phase modulations to input signals for each pillbox antenna structure. Amplitude and phase modulations enable constructive and destructive interference between neighboring pillbox antenna structures to enhance the resulting beam or create nulls to exclude interfering signals. Sets of pillbox antenna structures may be stacked and angularly offset to correct crossover sectors. Alternatively, or in addition, sets of pillbox antenna structures may be adapted to operate in different, distinct frequency bands or transmit/receive mode.

Referring toFIG.1, block diagrams of pillbox antennas130according to an exemplary embodiment are shown. Pillbox antennas130include a feed element104disposed to produce signals that may be reflected via a first reflector100; the resulting signals are reflected via a parabolic reflector102to produce a planar wave.

In at least one embodiment, an omnidirectional antenna includes a plurality of pillbox structures122,124,126,128. The pillbox structures122,124,126,128may be disposed periodically about an axis; for example, four pillbox structures122,124,126,128may be disposed about an axis, offset by 90° from each other. Each pillbox structure122,124,126,128includes a feed element and feed element reflector106,110,114,118, and a second reflector108,112,116,120disposed so that each second reflector108,112,116,120covers some arc of the area around the axis. While the second reflector108,112,116,120generally corresponds to the parabolic reflector102in its disposition with respect to the feed element reflector, the second reflectors108,112,116,120of the pillbox structures122,124,126,128may be shaped to produce a wider beam than is generally produced by a traditional pillbox antenna130. Alternatively, or in addition, the spatial relationship between the feed element reflector106,110,114,118and the second reflector108,112,116,120may be shorter that traditional pillbox antennas130to produce a wider beam (as opposed to the highly constrained directional beam of traditional pillbox antennas130).

Each pillbox structure122,124,126,128may be fed independently to produce selectively directional signals or, when all pillbox structures122,124,126,128are fed, the system produces an omnidirectional signal. A feed layer for the pillbox structures122,124,126,128may include switching elements to feed one or more of the pillbox structures122,124,126,128independently.

In at least one embodiment, the pillbox structures122,124,126,128may be disposed and operated at wavelengths such that neighboring beams may interact via constructive and destructive interference. Such constructive and destructive interference may enable beam control (i.e., radiation pattern synthesis and/or number of beams) not otherwise possible with pillbox antennas130.

Each pillbox structure122,124,126,128may be fed signals with distinct phase relationships to enable constructive and/or destructive interference of the corresponding beams to further enhance the omnidirectional nature of the beams, especially at the interface between pillbox structures122,124,126,128.

Simulations show that the second reflector108,112,116,120may be flattened (i.e., the curvature enlarged to produce a wide beam) to produce about 85° of coverage without compromising the resulting beam due to spillover and scattering.

In at least one embodiment, the pillbox structures122,124,126,128may comprise plated plastic filled with air. Alternatively, the arcs of the pillbox structures122,124,126,128may be embodied in a printed circuit board as an array of vias (i.e., substrate integrated waveguide, as described within the literature). In either case, the aperture side of the pillbox structure122,124,126,128may be flared to adjust beam width and gain.

A pillbox radiating element functions as a parallel plate waveguide radiator that has a DC cut off frequency in a transverse electromagnetic mode with aperture height effects matching into free space, adjustable by aperture flare/shaping. In contrast, the height of a Circular Parasitic Array (aka CPA) is fundamentally a ¼ wave monopole in free space, which is 3 inches tall at 1.0 GHz. Each pillbox structure122,124,126,128may be conceptualized as a one-dimensional prime focus or Cassegrain/Gregorian cylindrical or parabolic reflector antenna. Parallel plate waveguide pillboxes have high radiating efficiency and broad bandwidth due to geometric optics ray collimation properties.

Referring toFIG.2, a block diagram of an antenna according to an exemplary embodiment is shown. The antenna includes a plurality of pillbox structures200,202,204,206disposed around an axis. Each pillbox structure200,202,204,206may include a feed element reflector and a second reflector having a curvature to produce a beam such that the beams of neighboring pillbox structures200,202,204,206intersect or overlap.

Traditional parasitic arrays having a single monopole and a set of periphery parasitic elements require a switching diode for each parasitic element. In some applications (i.e., CPA), 32 or more switching elements may be necessary with a corresponding demand for DC power. In at least one embodiment, an antenna including pillbox structures200,202,204,206may require four switching elements. Furthermore, embodiments of the present disclosure may be smaller in height than a monopole antenna and an array of parasitic elements, particularly for S band and below frequencies.

It may be appreciated that while four sectored antennas are shown herein, antennas with more than four sectors are envisioned. More sectors (i.e., more pillbox structures200,202,204,206) may increase the diameter of the antenna.

Referring toFIG.3, a block diagram of an antenna according to an exemplary embodiment is shown. The antenna includes a plurality of pillbox structures300,302,304,306disposed around an axis. Each pillbox structure300,302,304,306may include a feed element reflector and a second reflector having a curvature to produce a beam such that the beams of neighboring pillbox structures300,302,304,306intersect or overlap.

A feed element308driving the pillbox structures300,302,304,306may include a set of switches310and a transmit/receive module312,314,316,318, each corresponding to one of the pillbox structures300,302,304,306. The transmit/receive modules apply phase (and amplitude) adjustments to the signals of the corresponding pillbox structure300,302,304,306. Phase control enables the side lobe adjustment and beam width control when operating in an omnidirectional mode in accordance to circular antenna array phase-mode theory, as described in the literature. For example, the transmit/receive modules312,314,316,318may apply a phase progression to alter properties of the resulting omnidirectional signal.

In at least one embodiment, the switches310and transmit/receive modules312,314,316,318may comprise RF integrated circuits for element level amplitude and phase weighting; amplitude weighting enables side lobe adjustment and beam width adjustment. Such switching enables sector switching, azimuth beam steering, azimuth nulling, phase modal excitation.

Referring toFIG.4, a block diagram of an antenna according to an exemplary embodiment is shown. The antenna includes a plurality of pillbox structures400,402,404,406disposed around an axis. Each pillbox structure400,402,404,406may include a feed element reflector and a second reflector having a curvature to produce a beam such that the beams of neighboring pillbox structures400,402,404,406intersect or overlap. A feed element408driving the pillbox structures400,402,404,406may include a set of switches410and a transmit/receive module412,414,416,418, each corresponding to one of the pillbox structures400,402,404,406to apply phase adjustments.

In at least one embodiment, set of switching elements410and transmit/receive modules412,414,416,418may alter the amplitude and phase of input signals to each pillbox structure400,402,404,406to produce a null420. Amplitude and phase adjustment specific to each pillbox structure400,402,404,406may enable as one fewer null420than the number of pillbox structures400,402,404,406to address interference such as jamming signals. The determination of amplitude and phase adjustments in real-time may require additional processing elements as well as data corresponding to the position of such interference sources.

Referring toFIG.5, a block diagram of an antenna according to an exemplary embodiment is shown. The antenna includes a first set of pillbox structures creating radiation patterns500,502,504,506disposed around an axis, and a second set of pillbox structures creating radiation patterns508,510,512,514disposed around the axis and linearly offset along the axis from the first set of pillbox structures500,502,504,506(i.e., the sets of pillbox structures are staked vertically to support different frequency or transmit/receive duality).

In at least one embodiment, the second set of pillbox structures508,510,512,514is angularly offset from the first set of pillbox structures500,502,504,506. For example, the second set of pillbox structures508,510,512,514may be rotated 45°. For each set pillbox structures, neighboring pillbox structures define crossover sectors where beams overlap and are relatively weak. Rotating the sets of pillbox structures with respect to each other allows such crossover sectors to be staggered. The resulting angularly offset beams may be blended via backend processing elements516for a lower omni ripple and smoother radiation pattern. In at least one embodiment, where the pillbox structures500,502,504,506,508,510,512,514comprise substrate integrated waveguides, the overall height of the stacked antenna may be low.

Referring toFIG.6, a block diagram of an antenna according to an exemplary embodiment is shown. The antenna includes a plurality of stacked sets of pillbox structures600,602,604,606. Each set of pillbox structures600,602,604,606is dimensionally optimized and configured to operate in a separate, distinct frequency band. For example, a first set of pillbox structures600may be configured to operate in the Ku band, a second set of set of pillbox structures602may be configured to operate in the C band, a third set of pillbox structures604may be configured to operate in the S band, and a fourth set of pillbox structures606may be configured to operate in the L band.

In at least one embodiment, the antenna may include a feed layer608including a plurality of switches and transmit/receive modules. The switches and transmit/receive modules may be in electronic communication with the various sets of pillbox structures600,602,604,606via vias610,612that may be uniquely associated with a pillbox structure to minimize power and maximize frequency bandwidth. In at least one embodiment, rigid coaxial cable structures610,612,614may be generally disposed to passthrough the paraboloid antenna walls of the pillbox structures to minimize parasitic effects.

Pillbox structures are self-shielding. Placing sets of pillbox structures600,602,604,606configured for differing frequencies on top of each other does not induce first order effect radiation performance or impedance matching. In at least one embodiment, each set of pillbox structures600,602,604,606may have local ground plane sloping and/or aperture flaring to create fixed, but shaped elevation patterns.

Pillbox structures configured to operate in general as essentially parallel plate waveguide radiators in a transverse-electromagnetic mode (TEM) and have a DC cut-off frequency. Aperture height effects matching into free space, which can be adjusted by aperture flare/shaping.

Referring toFIG.7, radiation patterns700,702of a stacked antenna with separate sets of pillbox structures are shown. Where the antenna includes stacked, angularly offset sets of pillbox structures, a feed layer may configure the pillbox structures such that a first set of pillbox structures is configured for transmission while a second set of pillbox structures is configured for reception. In at least one embodiment, transmit and receive beams may be isolated by rotation such that a first transmit beam704is offset from a first receive beam706.

In at least one embodiment, individual pillbox structures within sets of pillbox structures may be configured, via the corresponding feed layer, for either a transmission beam708or a receive beam710,712,714. Designated transmit pillbox structures and receive pillbox structures may be angular offset between stacked sets of pillbox structures. Such configuration may produce a radiation pattern702where transmission and reception may be isolated by time delay, Time Division Multiplexing (TDM) the various antenna structures, and frequency hopping. Alternatively, it is possible to enable full duplex operation if the transmit and receive beams do not point in the same direction, which minimizes parasitic transmit-to-receive mutual coupling, which in turn prevents receiver de-sensing or even destruction receiver circuitry damage that can be caused my excessive RF energy exciting the receiver behind its respective pill box antenna.

Referring toFIG.8, a block diagram of an antenna with stacked sets of pillbox structures800,802is shown. Where the antenna includes stacked, separate sets of pillbox structures800,802, a first set of pillbox structures800may include pillbox structures804configured for low frequency operation and a second set of pillbox structures802may include pillbox structures806configured for high frequency operation. Individual pillbox structures804,806may be configured to produce modified beam sectors with individual controllable beam width and position. Furthermore, gain and null variation is possible. It may be appreciated that while two sets of stacked pillbox structures800,802are shown, more than two stacked layers are envisioned.

Embodiments of the present disclosure enable broad, multi-band, full duplex operation for different transmit/receive frequency bands. A feed layer with fast switching (e.g., RF) enables frequency hopping, transmit/receive switching, and beam switching. Depending on the number of sectors in a stack, gain, beamwidth, and beam nulls may be altered. Embodiments of the present disclosure require significantly fewer switches than parasitic array antennas with equivalent capabilities, and utilizes less complex beam steering electronics.

It is believed that the inventive concepts disclosed herein and many of their attendant advantages will be understood by the foregoing description of embodiments of the inventive concepts, and it will be apparent that various changes may be made in the form, construction, and arrangement of the components thereof without departing from the broad scope of the inventive concepts disclosed herein or without sacrificing all of their material advantages; and individual features from various embodiments may be combined to arrive at other embodiments. The forms herein before described being merely explanatory embodiments thereof, it is the intention of the following claims to encompass and include such changes. Furthermore, any of the features disclosed in relation to any of the individual embodiments may be incorporated into any other embodiment.