Metamaterial filtering antenna

Abstract

A metamaterial filtering antenna includes a host waveguide, a plurality of metamaterial resonant elements, a feed port, and a radiation port. The plurality of metamaterial resonant elements are arranged inside the host waveguide. Each of the plurality of metamaterial resonant elements are electromagnetically coupled to at least one adjacent metamaterial resonant element by being placed at a subwavelength distance from at least one adjacent metamaterial resonant element. The feed port is coupled to a first side of the host waveguide and is configured to couple a radiofrequency (RF) signal to the host waveguide. The radiation port is coupled to a second side of the host waveguide and is configured to receive an electromagnetic wave from the host waveguide and radiate the electromagnetic wave to outside the metamaterial filtering antenna. The electromagnetic wave is generated by the plurality of metamaterial resonant elements through filtering the RF signal.

Description

METAMATERIAL FILTERING ANTENNA TECHNICAL FIELD

[0001] The present disclosure generally relates to antennas, and particularly, to metamaterial based antennas. BACKGROUND ART

[0002] The use of satellite communication and telecommunication services is in constant progress. The trend is to miniaturize the chain of reception and emission in embedded systems to avoid too much weight for a satellite, for example, and to reduce a volume occupied by all different devices. This may lead to finding a way to compress radiofrequency (RF) parts of a transmitter / emitter, which may be particularly interesting for transceiver elements that are not integrated in a monolithic way, such as an antenna and filters at a front end. In many wireless communication systems, RF filters may usually be placed right after antennas. Since size reduction and low profile structure are a trend in circuit design, it is desired to integrate highly selective band-pass filters and antennas in single modules, referred to as “filtering antenna”, with passing the desired frequencies, rejecting out-of-band interferences, and radiating functions simultaneously.

[0003] Newer generations of satellite systems may use active or passive antennas with steerable patterns or beams. Having electronically steerable array antennas may need to have low spacing between antenna units, for example, less than a half of a wavelength. This requirement may be difficult to achieve using conventional technologies, such as hollow waveguides and horn antennas. On the other hand, steerable phased array antennas using other technologies, such as dielectric antennas or planar antennas may result in less efficiency.

[0004] Metamaterials are artificial materials that exhibit negative permittivity and / or permeability. Metamaterials may also be inherently resonant, i.e., they may strongly shape electromagnetic radiation at a certain range of frequencies. Due to the ability in subwavelength manipulation of electromagnetic radiation, metamaterials have been utilized for designing electromagnetic radiation filters [US Patents no.10,620,343 B2 and 10,996,385 B2]. This may encourage using metamaterials to design filtering antennas. However, metamaterial filters may demonstrate a very narrowband transmission, high loss, and high group velocity dispersion (GVD) around a resonance frequency. Moreover, a guided mode that may be created inside abandgap of resonant metamaterials may limit a passband and / or rejection band of designed filters to the bandgap of resonant metamaterials. Besides, small metamaterial elements cannot be used easily as an antenna and may radiate in a wide frequency band with high efficiency

[0005] There is, therefore, a need for a microwave and millimeter wave antenna that may be easily fabricated with a low loss, wide band, and a highly miniaturized size. There is also a need for an efficient microwave and millimeter wave antenna that may be integrated with a band-pass filter in a single module. SUMMARY OF THE DISCLOSURE

[0006] This summary is intended to provide an overview of the subject matter of this patent, and is not intended to identify essential elements or key elements of the subject matter, nor is it intended to be used to determine the scope of the claimed implementations. The proper scope of this patent may be ascertained from the claims set forth below in view of the detailed description below and the drawings.

[0007] In one general aspect, the present disclosure describes an exemplary metamaterial filtering antenna. An exemplary metamaterial filtering antenna may include a host waveguide, one or more metamaterial resonant elements, a feed port, and a radiation port. An exemplary one or more metamaterial resonant elements may be arranged inside the host waveguide. In an exemplary embodiment, each of the one or more metamaterial resonant elements may be electromagnetically coupled to at least one adjacent metamaterial resonant element of the one or more metamaterial resonant elements by being placed at a subwavelength distance from at least one adjacent metamaterial resonant element. An exemplary feed port may be coupled to a first side of the host waveguide. In an exemplary embodiment, the feed port may be configured to couple a primary radiofrequency (RF) signal to the host waveguide. An exemplary radiation port may be coupled to a second side of the host waveguide. An exemplary second side may oppose the first side. An exemplary radiation port may be configured to receive an electromagnetic wave from the host waveguide and radiate the electromagnetic wave to outside the metamaterial filtering antenna. An exemplary electromagnetic wave may be generated by the one or more metamaterial resonant elements through filtering the primary RF signal. An exemplary metamaterial filtering antenna may further include a dielectric cover that may be attached to the radiation port.

[0008] In an exemplary embodiment, the radiation port may include a conductive sheet and a slot. An exemplary conductive sheet may be attached at the second side between a third side of the host waveguide and a fourth side of the host waveguide. An exemplary third side may oppose the fourth side. An exemplary slot may be etched on the conductive sheet and may be configured to be electromagnetically coupled to at least one of the one or more metamaterial resonant elements by being positioned at a subwavelength distance from at least one of the one or more metamaterial resonant elements.

[0009] An exemplary slot may include an H-shaped slot that may be etched at a center of the conductive sheet. An exemplary one or more metamaterial resonant elements may include an array of metallic pins that may be arranged along a straight line inside the host waveguide. An exemplary last metallic pin of the array of metallic pins may be placed at a subwavelength distance from the H-shaped slot.

[0010] An exemplary slot may include a horizontal bowtie-shaped slot that may be etched at a center of the conductive sheet. An exemplary horizontal bowtie-shaped slot may be associated with a horizontal polarization of the metamaterial filtering antenna. In an exemplary embodiment, the horizontal bowtie-shaped slot may include a first semi-triangular shape, a second semi-triangular shape, and a horizontal axis. An exemplary second semi-triangular shape may coincide with the first semi-triangular shape at a central point of the horizontal bowtie-shaped slot. An exemplary horizontal axis may pass through the central point. In an exemplary embodiment, each of the first semi-triangular shape and the second semi-triangular shape may be symmetric with respect to the horizontal axis.

[0011] In an exemplary embodiment, the one or more metamaterial resonant elements may include one or more metal sheets that may be sequentially arranged inside the host waveguide parallel with the conductive sheet. An exemplary last metal sheet of the one or more metal sheets may be placed at a subwavelength from the conductive sheet. In an exemplary embodiment, each respective metal sheet of the one or more metal sheets may include a respective horizontal bowtie-shaped slot that may be etched at a center of the respective metal sheet. An exemplary respective horizontal bowtie-shaped slot may include a respective first semi-triangular shape, a respective second semi-triangular shape, and a respective horizontal axis. An exemplary respective second semi-triangular shape may coincide with the respective first semi-triangular shape at a respective central point of the respective horizontal bowtie- shaped slot. An exemplary respective horizontal axis may be parallel with the first horizontalaxis and may pass through the respective central point. In an exemplary embodiment, each of the respective first semi-triangular shape and the respective second semi-triangular shape may be symmetric with respect to the respective horizontal axis.

[0012] An exemplary slot may further include a vertical bowtie-shaped slot that may be etched at the center of the conductive sheet. An exemplary vertical bowtie-shaped slot may be associated with a vertical polarization of the metamaterial filtering antenna. In an exemplary embodiment, the vertical bowtie-shaped slot may include a third semi-triangular shape, a fourth semi-triangular shape, and a vertical axis. An exemplary fourth semi-triangular shape may coincide with the third semi-triangular shape at the central point. An exemplary vertical axis may pass through the central point and may be perpendicular to the horizontal axis. In an exemplary embodiment, each of the third semi-triangular shape and the fourth semi-triangular shape may be symmetric with respect to the vertical axis.

[0013] In an exemplary embodiment, each respective metal sheet of the one or more metal sheets may further include a respective vertical bowtie-shaped slot that may be etched at the center of the respective metal sheet. An exemplary respective vertical bowtie-shaped slot may include a respective third semi-triangular shape, a respective fourth semi-triangular shape, and a respective vertical axis. An exemplary respective fourth semi-triangular shape may coincide with the respective third semi-triangular shape at the respective central point. An exemplary respective vertical axis may pass through the respective central point and may be perpendicular to the respective horizontal axis. In an exemplary embodiment, each of the respective third semi-triangular shape and the respective fourth semi-triangular shape may be symmetric with respect to the respective vertical axis.

[0014] In an exemplary embodiment, the feed port may include a ground plane, a dielectric substrate, a metal patch, a via, and a microstrip feed line. An exemplary ground plane may be attached to the first side and may be electrically coupled to the host waveguide at the first side. An exemplary dielectric substrate may be attached to a top surface of the ground plane between the ground plane and the host waveguide. An exemplary metal patch may be attached to a top surface of the dielectric substrate between the dielectric substrate and the host waveguide and may be configured to be electromagnetically coupled to at least one metamaterial resonant element of the one or more metamaterial resonant elements by being positioned at a subwavelength distance from at least one metamaterial resonant element. An exemplary via may be extended from the ground plane to the metal patch through the dielectric substrate. Anexemplary microstrip feed line may pass through the via and may be configured to couple the primary RF signal to the host waveguide by being connected to the metal patch. In an exemplary embodiment, the microstrip feed line may be associated with a horizontal polarization of the metal patch.

[0015] An exemplary feed port may further include an additional via and an additional microstrip feed line. An exemplary additional via may be extended from the ground plane to the metal patch through the dielectric substrate. An exemplary additional microstrip feed line may pass through the additional via and may be configured to couple a secondary RF signal to the host waveguide by being connected to the metal patch. An exemplary secondary RF signal may be independent from the primary RF signal. In an exemplary embodiment, the additional microstrip feed line may be associated with a vertical polarization of the metal patch.

[0016] Other exemplary systems, methods, features and advantages of the implementations will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the implementations, and be protected by the claims herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawing figures depict one or more implementations in accord with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements.

[0018] FIG.1A shows a schematic of a metamaterial filtering antenna, consistent with one or more exemplary embodiments of the present disclosure.

[0019] FIG.1B shows a schematic of a three-dimensional (3D) cross-section of a metamaterial filtering antenna with an insulating cover, consistent with one or more exemplary embodiments of the present disclosure.

[0020] FIG. 2 shows a schematic of different implementations of a radiation port, consistent with one or more exemplary embodiments of the present disclosure.

[0021] FIG. 3A shows a schematic of a 3D cross-section of a metamaterial filtering antenna with an H-shaped slot, consistent with one or more exemplary embodiments of the present disclosure.

[0022] FIG. 3B shows a schematic of a front view of a radiation port with an H-shaped slot, consistent with one or more exemplary embodiments of the present disclosure.

[0023] FIG. 4A shows a schematic of an exploded view of a metamaterial filtering antenna with bowtie-shaped slots, consistent with one or more exemplary embodiments of the present disclosure.

[0024] FIG. 4B shows a schematic of a front view of a horizontal bowtie-shaped slot, consistent with one or more exemplary embodiments of the present disclosure.

[0025] FIG.4C shows a schematic of a front view of a vertical bowtie-shaped slot, consistent with one or more exemplary embodiments of the present disclosure. DESCRIPTION OF EMBODIMENTS

[0026] In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and / or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings.

[0027] The following detailed description is presented to enable a person skilled in the art to make and use the methods and devices disclosed in exemplary embodiments of the present disclosure. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that these specific details are not required to practice the disclosed exemplary embodiments. Descriptions of specific exemplary embodiments are provided only as representative examples. Various modifications to the exemplary implementations will be readily apparent to one skilled in the art, and the general principles defined herein may be applied to other implementations and applications without departing from the scope of the present disclosure. The present disclosure is not intended to be limited to the implementations shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.

[0028] Herein is disclosed an exemplary metamaterial filtering antenna. An exemplary antenna may include a host waveguide that is attached to a feed port and a radiation port. An exemplary feed port may deliver a radio frequency (RF) signal to the host waveguide to be filtered and be radiated outside the antenna through the radiation port. An exemplary host waveguide mayinclude a number of metamaterial resonant elements that may be sequentially arranged inside the waveguide so that a metamaterial structure with an exemplary passband and stopband may be obtained. An exemplary bandwidth of the filter may be tuned by changing the specifications (such as arrangement, height, inter-distance, etc.) of the metamaterial resonant elements.

[0029] An exemplary radiation port may include slots that may be etched on a conductive sheet. An exemplary slot may be electromagnetically coupled to the metamaterial resonant elements so that energy of an exemplary RF signal may be received at the slot from the metamaterial resonant elements and may be radiated outwards through the slot. An exemplary slot may have several different shapes, such as a square shape, a rectangular shape, a cross shape, an H shape, a bowtie shape, or a pair of orthogonal bowtie shapes coinciding at a center of the shapes. An exemplary pair of orthogonal slots may provide a dual polarization capability for the antenna. As a result, two independent RF signals may be fed to an exemplary antenna via two exemplary microstrip lines through the feed port and may be efficiently transmitted in two orthogonal directions so that signal interference may be avoided.

[0030] FIG.1A shows a schematic of a metamaterial filtering antenna, consistent with one or more exemplary embodiments of the present disclosure. An exemplary metamaterial filtering antenna 100 may include a host waveguide 102, one or more metamaterial resonant elements 104, a feed port 106, and a radiation port 108. In an exemplary embodiment, one or more metamaterial resonant elements 104 may be arranged inside host waveguide 102. In an exemplary embodiment, each of one or more metamaterial resonant elements 104 may be electromagnetically coupled to at least one adjacent metamaterial resonant element of one or more metamaterial resonant elements 104 by being placed at a subwavelength distance from at least one adjacent metamaterial resonant element. In an exemplary embodiment, a “subwavelength distance” may refer to a distance less than about ^^^^ / 4 where ^^^^is an operating wavelength of metamaterial filtering antenna 100. In an exemplary embodiment, wavelength ^^^^may be equal to ^^ / (√^^ ^^^^) where ^^ is the speed of light, ^^ is a permittivity of material (such as air, silicon, etc.) that may fill host waveguide 102, and ^^^^an operating frequency of metamaterial filtering antenna 100. For example, a metamaterial resonant element 110 may be placed at a subwavelength distance 112 from an adjacent metamaterial resonant element 114. In an exemplary embodiment, a “metamaterial resonant element” may refer to a subwavelength component within a metamaterial structure designed to exhibit resonance atspecific frequencies, enabling wave manipulation. Exemplary metamaterial resonant elements may interact by propagating waves and radiations since they are open resonators.

[0031] In an exemplary embodiment, one or more metamaterial resonant elements 104 may locally resonate in host waveguide 102 which may create a passband and a stopband. Each exemplary resonance may generate a high unloaded Q pole and deep zero with critical coupling to an adjacent resonator. In an exemplary embodiment, one or more metamaterial resonant elements 104 may make a bandgap artificial material that may provide a deep and sharp metamaterial bandgap (that is, negative permittivity and / or negative permeability) right after an exemplary passband.

[0032] In an exemplary embodiment, one or more metamaterial resonant elements 104 may be coupled via electric and magnetic fields (or modal electric and magnetic fields) generated by one or more metamaterial resonant elements 104. In an exemplary embodiment, energy may be coupled between or from one metamaterial resonant element to another by this coupling. In an exemplary embodiment, host waveguide 102 may be configured to support evanescent modes or waves of microwave or millimeter electromagnetic wave. For this purpose, in an exemplary embodiment, each of a width 115A and a height 115B of host waveguide 102 may be smaller than ^^^^ / 2. In an exemplary embodiment, host waveguide 102 may have a waveguide cut-off frequency ^^^^below which host waveguide 102 may not support a propagating mode or wave. For example, no transverse electric TE mode of microwave or millimeter electromagnetic wave may be propagated in host waveguide 102 below cut-off frequency ^^^^. In an exemplary embodiment, cut-off frequency ^^^^may refer to a lowest cutoff frequency of host waveguide 102 in an absence of any metamaterial resonant element inside host waveguide 102. An exemplary resonance frequency ^^^^of each of one or more metamaterial resonant elements 104 may be less than cut-off frequency ^^^^.

[0033] In an exemplary embodiment, feed port 106 may be coupled to a first side 116 of host waveguide 102. In an exemplary embodiment, feed port 106 may be configured to couple a primary RF signal to host waveguide 102. In an exemplary embodiment, radiation port 108 may be coupled to a second side 118 of host waveguide 102. In an exemplary embodiment, second side 118 may oppose first side 116. In an exemplary embodiment, radiation port 108 may be configured to receive an electromagnetic wave from host waveguide 102 and radiate the electromagnetic wave to outside metamaterial filtering antenna 100. An exemplaryelectromagnetic wave may be generated by one or more metamaterial resonant elements 104 through filtering the primary RF signal.

[0034] In an exemplary embodiment, radiation port 108 may include a conductive sheet 120 and a slot 122. In an exemplary embodiment, conductive sheet 120 may be attached at second side 118 between a third side 124 of host waveguide 102 and a fourth side 126 of host waveguide 102. In an exemplary embodiment, third side 124 may oppose fourth side 126. In an exemplary embodiment, conductive sheet 120 may be made of metal. In an exemplary embodiment, slot 122 may be etched on conductive sheet 120 and may be configured to be electromagnetically coupled to at least one of one or more metamaterial resonant elements 104 by being positioned at a subwavelength distance from at least one of one or more metamaterial resonant elements 104. For example, slot 122 may be positioned at a subwavelength distance 128 from a metamaterial resonant element 130.

[0035] FIG.1B shows a schematic of a three-dimensional (3D) cross-section of a metamaterial filtering antenna with an insulating cover, consistent with one or more exemplary embodiments of the present disclosure. An exemplary metamaterial filtering antenna 132 may be similar to metamaterial filtering antenna 100 and may include similar elements. For example, metamaterial filtering antenna 132 may include a host waveguide 134 (similar to host waveguide 102) and a radiation port 136 (similar to radiation port 108). In an exemplary embodiment, metamaterial filtering antenna 132 may further include a dielectric cover 138 that may be attached to radiation port 136. In an exemplary embodiment, dielectric cover 138 may be an insulator and may be configured to protect radiation port 108 and its elements. In an exemplary embodiment, dielectric cover 138 may also enhance radiation efficiency and a gain of metamaterial filtering antenna 132.

[0036] FIG. 2 shows a schematic of different implementations of a radiation port, consistent with one or more exemplary embodiments of the present disclosure. Exemplary radiation ports 202, 204, 205, 206, and 207 may respectively have slots 208 (etched on a conductive sheet 209), 210 (etched on a conductive sheet 211), 212 (etched on a conductive sheet 213), 214 (etched on a conductive sheet 215), and 216 (etched on a conductive sheet 217). In an exemplary embodiment, slots 208, 210, 212, 214, and 216 may have different shapes. However, an exemplary perimeter of slots 208, 210, 212, 214, and 216 may be in a range of about 0.4 ^^^^to 1.4 ^^^^. In an exemplary embodiment, a “perimeter” of a slot may refer to a length of a boundary of a geometric shape of the slot.

[0037] FIG. 3A shows a schematic of a 3D cross-section of a metamaterial filtering antenna with an H-shaped slot, consistent with one or more exemplary embodiments of the present disclosure. Referring to FIGs. 1A and 3A, an exemplary metamaterial filtering antenna 300 may be similar to metamaterial filtering antenna 100 and may include similar elements. For example, metamaterial filtering antenna 300 may include a host waveguide 302 (similar to host waveguide 102), one or more metamaterial resonant elements 304 (similar to one or more metamaterial resonant elements 104), and a radiation port 306 (similar to radiation port 108). An exemplary feed port of metamaterial filtering antenna 300 is not shown in FIG. 3. In an exemplary embodiment, radiation port 306 may include a conductive sheet 308 (similar to conductive sheet 120) and a slot (similar to slot 122). An exemplary slot may include an H- shaped slot 310 that may be etched at a center of conductive sheet 308.

[0038] In an exemplary embodiment, one or more metamaterial resonant elements 304 may include an array of metallic pins that may be arranged along a straight line 312 inside host waveguide 302. An exemplary last metallic pin 314 of the array of metallic pins may be placed at a subwavelength distance from H-shaped slot 310.

[0039] FIG. 3B shows a schematic of a front view of a radiation port with an H-shaped slot, consistent with one or more exemplary embodiments of the present disclosure. Referring to FIGs. 1A, 3A, and 3B, in an exemplary embodiment, dimensions of metamaterial filteringantenna 300 may satisfy a set of conditions defined by the following:0.2 ^^ ^^ < ^^ < 0.6 ^^ ^^ Inequation (1a)0.05 ^^ ^^ < ^^ ^^ < 0.2 ^^ ^^ Inequation (1b)^^ ^^ < 0.1 ^^ ^^ Inequation (1c)0.05 ^^ ^^ < ^^ ^^ < 0.5 ^^ ^^ Inequation (1d)0.05 ^^ ^^ < ℎ ^^ < 0.4 ^^ ^^ Inequation (1e)0.4 ^^ ^^ < ^^ ^^ < 1.2 ^^ ^^ Inequation (1f)0.05 ^^ ^^ < ℎ ^^ < 0.25 ^^ ^^ Inequation (1g)0.02 ^^ ^^ < ^^ ^^ < 0.2 ^^ ^^ Inequation (1h)where ^^ represents each of a width 316A (similar to width 115A) and a height 316B (similar to height 115B) of host waveguide 302, ^^^^is a width 318 of a middle portion 320 of H-shaped slot 310, ^^^^is a width 322 of side portions 324 of H-shaped slot 310, ^^^^is a width 326 of H- shaped slot 310, ℎ^^is a height 328 of H-shaped slot 310, ^^^^is a perimeter (similar to perimeters of slots 208, 210, and 212 of FIG. 2) of H-shaped slot 310, ℎ^^is a height of eachmetallic pin of the array of metallic pins (for example, a height 330 of a metallic pin 332) , and ^^^^is a distance between each two successive metallic pins of the array of metallic pins (for example, a distance 334). In an exemplary embodiment, although width 316A and height 115B refer to dimensions of conductive sheet 308, they may be identical to corresponding dimensions of host waveguide 302 since conductive sheet 308 may substantially fit to host waveguide 302.

[0040] FIG. 4A shows a schematic of an exploded view of a metamaterial filtering antenna with bowtie-shaped slots, consistent with one or more exemplary embodiments of the present disclosure. Referring to FIGs. 1A and 4A, an exemplary metamaterial filtering antenna 400 may be similar to metamaterial filtering antenna 100 and may include similar elements. For example, metamaterial filtering antenna 400 may include a host waveguide 402 (similar to host waveguide 102), one or more metamaterial resonant elements 404 (similar to one or more metamaterial resonant elements 104), a feed port 406 (similar to radiation port 106), and a radiation port 408 (similar to radiation port 108). In an exemplary embodiment, radiation port 408 may include a conductive sheet 410 (similar to conductive sheet 120) and a slot (similar to slot 122). An exemplary slot may include a horizontal bowtie-shaped slot 412 that may be etched at a center of conductive sheet 410. In an exemplary embodiment, horizontal bowtie- shaped slot 412 may produce a horizontal polarization of metamaterial filtering antenna 400. In an exemplary embodiment, a “horizontal polarization” of metamaterial filtering antenna 400 may refer to a direction of electromagnetic fields produced by metamaterial filtering antenna 400 as energy radiates away from radiation port 108 through horizontal bowtie-shaped slot 412.

[0041] FIG. 4B shows a schematic of a front view of a horizontal bowtie-shaped slot, consistent with one or more exemplary embodiments of the present disclosure. In an exemplary embodiment, horizontal bowtie-shaped slot 412 may include a first semi-triangular shape 414, a second semi-triangular shape 416, and a horizontal axis 418. In an exemplary embodiment, second semi-triangular shape 416 may coincide with first semi-triangular shape 414 at a central point 420 of horizontal bowtie-shaped slot 412. In an exemplary embodiment, horizontal axis 418 may pass through central point 420. In an exemplary embodiment, each of first semi- triangular shape 414 and second semi-triangular shape 416 may be symmetric with respect to horizontal axis 418.

[0042] Referring to FIGs.4A and 4B, in an exemplary embodiment, one or more metamaterial resonant elements 404 may include one or more metal sheets (for example, a metal sheet 422)that may be sequentially arranged inside host waveguide 402 parallel with conductive sheet 410. An exemplary last metal sheet (for example, metal sheet 422) of the one or more metal sheets may be placed at a subwavelength from conductive sheet 410. In an exemplary embodiment, each respective metal sheet of the one or more metal sheets may include a respective horizontal bowtie-shaped slot that may be etched at a center of the respective metal sheet. For example, metal sheet 422 may include a horizontal bowtie-shaped slot 424 that may be etched at a center of metal sheet 422.

[0043] In an exemplary embodiment, horizontal bowtie-shaped slot 424 may be similar to horizontal bowtie-shaped slot 412 and may include similar elements. For example, horizontal bowtie-shaped slot 424 may include a semi-triangular shape similar to first semi-triangular shape 414, a semi-triangular shape similar to second semi-triangular shape 416, and a horizontal axis similar to and parallel with horizontal axis 418.

[0044] Referring again to FIGs.1A, 4A, and 4B, in an exemplary embodiment, dimensions ofmetamaterial filtering antenna 400 may satisfy a set of conditions defined by the following:0.4 ^^ ^^ < ^^ < 06 ^^ ^^ Inequation (2a)^^ < 0.25 ^^ ^^ Inequation (2b)0.05 ^^ ^^ < ^^ ^^ < 0.3 ^^ ^^ Inequation (2c)0.15 ^^^^< ^^^^< 0.25 ^^^^Inequation (2d)0.01 ^^ ^^ < ^^ ^^ < 0.1 ^^ ^^ Inequation (2e)0.3 ^^ ^^ < ^^ ^^ < 0.5 ^^ ^^ Inequation (2f)^^^^< ^^^^< 1.4 ^^^^Inequation (2g) where ^^ represents each of a width 426A (similar to width 115A) and a height 426B (similar to height 115B) of host waveguide 402, ^^ represents each of a thickness 428 of metal sheet 422 and a thickness 430 of conductive sheet 410, ^^^^is a distance between each two successive sheets (for example, a distance 432 between metal sheet 422 and conductive sheet 410), ^^^^is a maximum width 434 of horizontal bowtie-shaped slot 412 (and, in an exemplary embodiment, horizontal bowtie-shaped slot 424), ^^^^is a minimum width 436 of horizontal bowtie-shaped slot 412 (and, in an exemplary embodiment, horizontal bowtie-shaped slot 424), ^^^^is a length 438 of horizontal bowtie-shaped slot 412 (and, in an exemplary embodiment, horizontal bowtie-shaped slot 424), and ^^^^is a perimeter (similar to perimeters of slots 208, 210, and 212 of FIG.2) of horizontal bowtie-shaped slot 412 (and, in an exemplary embodiment, horizontal bowtie-shaped slot 424).

[0045] Referring again to FIG. 4A, an exemplary slot may further include a vertical bowtie- shaped slot 440 that may be etched at the center of conductive sheet 410. In an exemplary embodiment, vertical bowtie-shaped slot 440 may produce a vertical polarization of metamaterial filtering antenna 400. In an exemplary embodiment, a “vertical polarization” of metamaterial filtering antenna 400 may refer to a direction of electromagnetic fields produced by metamaterial filtering antenna 400 as energy radiates away from radiation port 108 through vertical bowtie-shaped slot 440. An exemplary vertical polarization may be orthogonal to the horizontal polarization, that is, exemplary electromagnetic waves that radiate through vertical bowtie-shaped slot 440 may propagate in a direction that is orthogonal to a propagation direction of exemplary electromagnetic waves that radiate through horizontal bowtie-shaped slot 412.

[0046] FIG.4C shows a schematic of a front view of a vertical bowtie-shaped slot, consistent with one or more exemplary embodiments of the present disclosure. Referring to FIGs.4B and 4C, in an exemplary embodiment, vertical bowtie-shaped slot 440 may include a third semi- triangular shape 442, a fourth semi-triangular shape 444, and a vertical axis 446. In an exemplary embodiment, fourth semi-triangular shape 444 may coincide with third semi- triangular shape 442 at central point 420. In an exemplary embodiment, vertical axis 446 may pass through central point 420 and may be perpendicular to horizontal axis 418. In an exemplary embodiment, each of third semi-triangular shape 442 and fourth semi-triangular shape 444 may be symmetric with respect to vertical axis 446. In an exemplary embodiment, different dimensions of vertical bowtie-shaped slot 440 may be in a similar range to corresponding dimensions of horizontal bowtie-shaped slot 412.

[0047] Referring to FIGs.4A, 4B, and 4C, in an exemplary embodiment, each respective metal sheet of the one or more metal sheets may further include a respective vertical bowtie-shaped slot that may be etched at a center of the respective metal sheet. For example, metal sheet 422 may further include a vertical bowtie-shaped slot 448 that may be etched at a center of metal sheet 422.

[0048] In an exemplary embodiment, vertical bowtie-shaped slot 448 may be similar to vertical bowtie-shaped slot 440 and may include similar elements. For example, vertical bowtie-shaped slot 448 may include a semi-triangular shape similar to third semi-triangular shape 442, a semi- triangular shape similar to fourth semi-triangular shape 444, and a vertical axis similar to and parallel with vertical axis 446 that may be perpendicular to horizontal axis 418.

[0049] Referring again to FIGs.1A and 4A, in an exemplary embodiment, feed port 406 may include a ground plane 450, a dielectric substrate 452, a metal patch 454, a via 456, and a microstrip feed line 458. In an exemplary embodiment, ground plane 450 may be attached to a first side 460 (similar to first side 116) of host waveguide 402. In an exemplary embodiment, ground plane 450 may be made of metal to be electrically coupled to host waveguide 402 at the first side 460.

[0050] In an exemplary embodiment, dielectric substrate 452 may be attached to a top surface of ground plane 450 between ground plane 450 and host waveguide 402. In an exemplary embodiment, metal patch 454 may be attached to a top surface of dielectric substrate 452 between dielectric substrate 452 and host waveguide 402 and may be configured to be electromagnetically coupled to one or more metamaterial resonant elements 404 by being positioned at a subwavelength distance 462 from one or more metamaterial resonant elements 404. In an exemplary embodiment, a width ^^^^1and a length ^^^^2of metal patch 454 may be in a range of about 0.01 ^^^^to about 0.3 ^^^^.

[0051] In an exemplary embodiment, via 456 may be extended from ground plane 450 to metal patch 454 through dielectric substrate 452. In an exemplary embodiment, microstrip feed line 458 may pass through via 456 and may be configured to couple the primary RF signal to host waveguide 402 by being connected to metal patch 454. In an exemplary embodiment, microstrip feed line 458 may be associated with a horizontal polarization of metal patch 454, that is, an exemplary energy of the primary RF signal may be transferred from metal patch 454 to horizontal bowtie-shaped slot 412 through horizontal bowtie-shaped slot 424 to be consequently radiated to outside metamaterial filtering antenna 400 through horizontal bowtie- shaped slot 412 in a horizontal direction.

[0052] In an exemplary embodiment, feed port 406 may further include an additional via 464 and an additional microstrip feed line 466. In an exemplary embodiment, additional via 464 may be extended from ground plane 450 to metal patch 454 through dielectric substrate 452. In an exemplary embodiment, additional microstrip feed line 466 may pass through additional via 464 and may be configured to couple a secondary RF signal to host waveguide 402 by being connected to metal patch 454. An exemplary secondary RF signal may be independent from the primary RF signal. In an exemplary embodiment, additional microstrip feed line 466 may be associated with a vertical polarization of metal patch 454, that is, an exemplary energy of the secondary RF signal may be transferred from metal patch 454 to vertical bowtie-shapedslot 440 through vertical bowtie-shaped slot 448 to be consequently radiated to outside metamaterial filtering antenna 400 through vertical bowtie-shaped slot 440 in a vertical direction. In an exemplary embodiment, metamaterial filtering antenna 400 may further include one or more additional dielectric substrates 468 that may be sequentially attached below a bottom surface of ground plane 450.

[0053] While the foregoing has described what are considered to be the best mode and / or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications, and variations that fall within the true scope of the present teachings.

[0054] Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain.

[0055] The scope of protection is limited solely by the claims that now follow. That scope is intended and should be interpreted to be as broad as is consistent with the ordinary meaning of the language that is used in the claims when interpreted in light of this specification and the prosecution history that follows and to encompass all structural and functional equivalents.

[0056] Except as stated immediately above, nothing that has been stated or illustrated is intended or should be interpreted to cause a dedication of any component, step, feature, object, benefit, advantage, or equivalent to the public, regardless of whether it is or is not recited in the claims.

[0057] It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. Relational terms such as first and second and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does notinclude only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “a” or “an” does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0058] The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various implementations. This is for purposes of streamlining the disclosure, and is not to be interpreted as reflecting an intention that the claimed implementations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed implementation. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.

[0059] While various implementations have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more implementations and implementations are possible that are within the scope of the implementations. Although many possible combinations of features are shown in the accompanying figures and discussed in this detailed description, many other combinations of the disclosed features are possible. Any feature of any implementation may be used in combination with or substituted for any other feature or element in any other implementation unless specifically restricted. Therefore, it will be understood that any of the features shown and / or discussed in the present disclosure may be implemented together in any suitable combination. Accordingly, the implementations are not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.

Claims

What is claimed is:

1. A metamaterial filtering antenna, comprising: a host waveguide; one or more metamaterial resonant elements arranged inside the host waveguide, each of the one or more metamaterial resonant elements configured to be electromagnetically coupled to at least one adjacent metamaterial resonant element of the one or more metamaterial resonant elements by being placed at a subwavelength distance from the at least one adjacent metamaterial resonant element; a feed port electrically coupled to a first side of the host waveguide and configured to couple a primary radiofrequency (RF) signal to the host waveguide; and a radiation port coupled to a second side of the host waveguide, the second side opposing the first side, the radiation port configured to: receive an electromagnetic wave from the host waveguide, the electromagnetic wave generated by the one or more metamaterial resonant elements through filtering the primary RF signal; and radiate the electromagnetic wave to outside the metamaterial filtering antenna, wherein the radiation port comprises: a conductive sheet attached at the second side between a third side of the host waveguide and a fourth side of the host waveguide, the third side opposing the fourth side; and a slot etched on the conductive sheet, the slot configured to be electromagnetically coupled to at least one of the one or more metamaterial resonant elements by being positioned at a subwavelength distance from the at least one of the one or more metamaterial resonant elements.

2. The metamaterial filtering antenna of claim 1, wherein the slot comprises an H-shaped slot etched at a center of the conductive sheet.

3. The metamaterial filtering antenna of claim 2, wherein the one or more metamaterial resonant elements comprise an array of metallic pins arranged along a straight line inside the hostwaveguide, a last metallic pin of the array of metallic pins placed at a subwavelength distance from the H-shaped slot.

4. The metamaterial filtering antenna of claim 3, wherein dimensions of the metamaterial filtering antenna satisfy a set of conditions defined by the following: 0.2^^< ^ < 0.6^^0.05^^< ^^< 0.2^^^^< 0.1^^0.05^^< ^^< 0.5^^0.05^^< ℎ^< 0.4^^0.4^^< ^^< 1.2^^0.05^^< ℎ^< 0.25^^0.02^^< ^^< 0.2^^where: ^ represents each of a width and a height of the host waveguide, ^^is a wavelength associated with an operating frequency of the metamaterial filtering antenna, ^^is a width of a middle portion of the H-shaped slot, ^^is a width of side portions of the H-shaped slot, ^^is a width of the H-shaped slot, ℎ^is a height of the H-shaped slot, ^^is a perimeter of the H-shaped slot, ℎ^is a height of each metallic pin of the array of metallic pins, and ^^is a distance between each two successive metallic pins of the array of metallic pins.

5. The metamaterial filtering antenna of claim 1, wherein the slot comprises a horizontal bowtie- shaped slot etched at a center of the conductive sheet, the horizontal bowtie-shaped slot associated with a horizontal polarization of the metamaterial filtering antenna, the horizontal bowtie-shaped slot comprising: a first semi-triangular shape;a second semi-triangular shape coinciding with the first semi-triangular shape at a central point of the horizontal bowtie-shaped slot; and a horizontal axis passing through the central point, each of the first semi-triangular shape and the second semi-triangular shape being symmetric with respect to the horizontal axis.

6. The metamaterial filtering antenna of claim 5, wherein the one or more metamaterial resonant elements comprise one or more metal sheets sequentially arranged inside the host waveguide parallel with the conductive sheet, a last metal sheet of the one or more metal sheets placed at a subwavelength from the conductive sheet, each respective metal sheet of the one or more metal sheets comprising a respective horizontal bowtie-shaped slot etched at a center of the respective metal sheet, the respective horizontal bowtie-shaped slot comprising: a respective first semi-triangular shape; a respective second semi-triangular shape coinciding with the respective first semi- triangular shape at a respective central point of the respective horizontal bowtie-shaped slot; and a respective horizontal axis parallel with the first horizontal axis and passing through the respective central point, each of the respective first semi-triangular shape and the respective second semi-triangular shape being symmetric with respect to the respective horizontal axis.

7. The metamaterial filtering antenna of claim 6, wherein dimensions of the metamaterial filtering antenna satisfy a set of conditions defined by the following: 0.4^^< ^ < 0.6^^^ < 0.25^^0.05^^< ^^< 0.3^^0.15^^< ^^< 0.25^^0.01^^< ^^< 0.1^^0.3^^< ^^< 0.5^^^^< ^^< 1.4^^where: ^ represents each of a width and a height of the host waveguide, ^^is a wavelength associated with an operating frequency of the metamaterial filtering antenna,^ represents a thickness of each of the one or more metal sheets and a thickness of the conductive sheet, ^^is a distance between each two successive metal sheets of the one or more metal sheets, ^^is a maximum width of the horizontal bowtie-shaped slot, ^^is a minimum width of the horizontal bowtie-shaped slot, ^^is a length of the horizontal bowtie-shaped slot, and ^^is a perimeter of the horizontal bowtie-shaped slot.

8. The metamaterial filtering antenna of claim 6, wherein the slot further comprises a vertical bowtie-shaped slot etched at the center of the conductive sheet, the vertical bowtie-shaped slot associated with a vertical polarization of the metamaterial filtering antenna, the vertical bowtie- shaped slot comprising: a third semi-triangular shape; a fourth semi-triangular shape coinciding with the third semi-triangular shape at the central point; and a vertical axis passing through the central point and perpendicular to the horizontal axis, each of the third semi-triangular shape and the fourth semi-triangular shape being symmetric with respect to the vertical axis.

9. The metamaterial filtering antenna of claim 8, wherein the each respective metal sheet of the one or more metal sheets further comprises a respective vertical bowtie-shaped slot etched at the center of the respective metal sheet, the respective vertical bowtie-shaped slot comprising: a respective third semi-triangular shape; a respective fourth semi-triangular shape coinciding with the third semi-triangular shape at the respective central point; and a respective vertical axis passing through the respective central point and perpendicular to the respective horizontal axis, each of the respective third semi-triangular shape and the respective fourth semi-triangular shape being symmetric with respect to the respective vertical axis.

10. The metamaterial filtering antenna of claim 1, wherein the feed port comprises:a ground plane attached to the first side and electrically coupled to the host waveguide at the first side; a dielectric substrate attached to a top surface of the ground plane between the ground plane and the host waveguide; a metal patch attached to a top surface of the dielectric substrate between the dielectric substrate and the host waveguide, the metal patch configured to be electromagnetically coupled to at least one metamaterial resonant element of the one or more metamaterial resonant elements by being positioned at a subwavelength distance from the at least one metamaterial resonant element; a via extended from the ground plane to the metal patch through the dielectric substrate; and a microstrip feed line passing through the via and configured to couple the primary RF signal to the host waveguide by being connected to the metal patch, the microstrip feed line associated with a horizontal polarization of the metal patch.

11. The metamaterial filtering antenna of claim 10, wherein the feed port further comprises: an additional via extended from the ground plane to the metal patch through the dielectric substrate; and an additional microstrip feed line passing through the additional via and configured to couple a secondary RF signal independent from the primary RF signal to the host waveguide by being connected to the metal patch, the additional microstrip feed line associated with a vertical polarization of the metal patch.

12. The metamaterial filtering antenna of claim 11, further comprising one or more additional dielectric substrates sequentially attached below a bottom surface of the ground plane.

13. The metamaterial filtering antenna of claim 11, wherein a width ^^of the metal patch satisfy a condition defined by the following: 0.01^^< ^^< 0.4^^where ^^is a wavelength associated with an operating frequency of the metamaterial filtering antenna.

14. The metamaterial filtering antenna of claim 1, further comprising a dielectric cover attached to the radiation port.

15. The metamaterial filtering antenna of claim 1, wherein: each of a width and a height of the host waveguide is smaller than ^^ / 2, where ^^is a wavelength associated with an operating frequency of the metamaterial filtering antenna; and a perimeter of the slot is in a range of 0.4^^to 1.4^^.

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