Phased array antenna

An antenna element having a vertically stacked structure and a phased array antenna that includes a plurality of antenna elements sharing a common conductive ground plane are described. The phased array antenna also includes a common conductive shell electrically coupled to the common conductive ground plane and extending away there from to encompass the antenna elements. The common conductive shell and the common conductive ground plane together define a common cavity having a common aperture. The phased array antenna also includes a common dielectric superstrate layer disposed over the common cavity at a predetermined distance from the antenna elements and a beam steering system coupled to the antenna elements and configured for steering an energy beam produced by the phased array antenna.

FIELD OF THE INVENTION

The present invention relates generally to directional beam forming antennas, and in particular, to a phased array antenna configuration.

BACKGROUND OF THE INVENTION

There are many applications employing antennas for transmitting and receiving electromagnetic signals in which antenna gain patterns with maxima for directional transmitting and receiving the signals is a desirable feature. One type of such antenna systems is an active Electronically Steered Phased Array (AESPA) having a plurality of individual antenna elements which are interconnected to enable electronic steering of the radiated beams of electromagnetic energy in space without physical movement of the whole array. The antenna elements in an array can be distributed either uniformly or non-uniformly over a prescribed surface area, and configured to provide the desired antenna radiation characteristics. The surface area of the phased array antenna may be either planar or curved. When desired, the antenna elements can be arranged in one or more planes. A circumference of the area may have any shape, e.g., circular, rectangular, or simply a straight line. Phased array antennas can, for example, be used in radar systems for estimating the direction-of-arrival of a target.

SUMMARY OF THE INVENTION

There is still a need in the art to provide a phased array antenna in which individual radiating antenna elements occupy rather small physical areas, preferably less than half of the operating wavelength, and have a substantial internal impedance matching level over a wide frequency band.

It would be advantageous to have a phased array antenna having radiation efficiency within a wide region of spatial angles.

There is also a need and it would be useful to have a phased array antenna having enhanced inter-element isolation, i.e., a phased array antenna with reduced coupling between the antenna elements, especially at extreme deflection angles.

There is further a need and it would be useful to have a phased array antenna performing selective augmentation in a preferable scanning sector.

There is further a need and it would be useful to have a phased array antenna having intrinsic flexibility, in order to make it applicable through a wide range of antenna sizes and operational frequency choices.

According to one general aspect, the present application provides a novel phased array antenna.

According to some embodiments, the phased array antenna includes a plurality of antenna elements sharing a common conductive ground plane for all the antenna elements and spaced apart at a predetermined distance from each other. The phased array antenna also includes a common conductive shell electrically coupled to the common conductive ground plane. The common conductive shell extends away from common conductive ground plane and encompasses the antenna elements. The common conductive shell and the common conductive ground plane together define a common cavity having a common aperture. The phased array antenna further includes a common dielectric superstrate layer disposed over the common cavity at a predetermined distance from the plurality of antenna elements. The phased array antenna also includes a beam steering system coupled to the antenna elements and configured for steering an energy beam produced by the phased array antenna.

According to some embodiments, a shape of a front of the common aperture is selected from a circular shape, an oval shape, a polygonal shape, and a D-shape.

According to one embodiment, walls of the common conductive shell are perpendicular to said common conductive ground plane.

According to another embodiment, walls of the common conductive shell are inwardly tapered from the common conductive ground plane towards the common aperture of the common cavity.

According to a further embodiment, walls of the common conductive shell are outwardly tapered from the common conductive ground plane towards the common aperture of the common cavity.

According to some embodiments, the common dielectric superstrate layer is arranged at the common aperture of the common cavity.

According to some embodiments, the common cavity is filled with a dielectric material having a dielectric permittivity ∈gequal to or greater than the dielectric permittivity of air.

A height Lgof the gap in the common cavity between the common superstrate layer and a top of the plurality of antenna elements depends on the desired deflection angles θ of the radiation beam. For example, the height Lgof the gap can be obtained by

Lg≈{λg⁡(x+n2),where⁢⁢0.6≤x≤0.65for⁢⁢0⁢°≤θ≤15⁢°λg⁡(0.01⁢⁢θ+0.327+0.6⁢⁢n),for⁢⁢15⁢°<θ≤45⁢°y⁢⁢λg,where⁢⁢0.45≤y≤0.5for⁢⁢45⁢°<θ≤70⁢°
where λg=λ0/√∈g, and λ0is the wavelength corresponding to the central operation frequency of the phased array antenna, ∈gis the dielectric permittivity of the dielectric material filling the gap in the common cavity, θ is the required deflection angle (in degrees), and n=0, 1, 2, . . . It should be noted that the case when n=0 is preferred.

According to some embodiments, thickness of the common dielectric superstrate layer (16) is uniform and complies with a relationship LSL≈λSL(0.2+n/2), where λSL=λ0/√∈SL, and λ0is the wavelength corresponding to the central operation frequency of said phased array antenna, ∈SLis the dielectric permittivity of the common dielectric superstrate layer (16), and n=0, 1, 2, . . .

According to some embodiments, a thickness of the common dielectric superstrate layer near walls of said common conductive shell is different than the thickness of the common dielectric superstrate layer at its center.

According to some embodiments, a side surface of the common dielectric superstrate layer is selected from a biplanar surface, biconcave surface, plano-concave surface, and convex-concave surface.

According to some embodiments, the common superstrate layer is made from a heat insulating material.

According to some embodiments, an outer surface of the common superstrate layer is covered with a heat insulating material.

According to some embodiments, each antenna element of the plurality of the antenna elements comprises a vertically stacked structure that includes an antenna element conductive shell extending away from and coupled to the common conductive ground plane. The antenna element conductive shell has a lumen to define an antenna element cavity having a bottom and an antenna element aperture.

The antenna element further includes a feeding radiator backed by the cavity and a parasitic radiator backed by the cavity and parasitically coupled to the feeding radiator. The feeding radiator is arranged at the bottom of the element cavity, whereas the parasitic radiator is disposed over and spaced apart from the feeding radiator.

The antenna element also includes a feed arrangement coupled to the feeding radiator and operable to provide radio frequency energy thereto.

According to some embodiments, each antenna element includes a bottom dielectric substrate. The bottom dielectric substrate can, for example, be common for all the antenna elements. However, when desired, at least a part of the antenna elements can have individual dielectric substrates separated from each other.

The bottom dielectric substrate has a bottom substrate underside having a lower bottom conductive coating adhesively bound thereto, and a bottom substrate upper side having an upper bottom conductive coating adhesively bound thereto. The lower bottom conductive coating and the upper bottom conductive coating are grounded; thereby forming the common conductive ground plane. The conductive shell of each antenna element is connected to said upper bottom conductive coating.

According to some embodiments, the feeding radiator includes a bottom slot arranged within the cavity in the upper bottom conductive coating to define a bottom feeding patch encompassed by the bottom slot.

According to some embodiments, each antenna element includes a top dielectric substrate which is common for all the antenna elements. The top dielectric substrate has a top substrate underside having a lower top coating adhesively bound thereto, and a top substrate upper side having an upper top coating adhesively bound thereto. The lower top coating is connected to the antenna element conductive shell.

According to one embodiment, the feeding radiator includes a top slot in the upper top coating to define a top radiating patch encompassed by the top slot.

According to another embodiment, the feeding radiator includes a top slot arranged within the cavity in the lower top coating to define a top radiating patch encompassed by the top slot.

According to some embodiments, the parasitic radiator for each antenna element is arranged at the antenna element aperture of the antenna element cavity.

According to some embodiments, each antenna element further comprises an intermediate layer sandwiched between the bottom dielectric substrate and the top dielectric substrate for providing a vertical separation and support to the bottom dielectric substrate and the top dielectric substrate. According to one example, the intermediate layer can be formed from a solid dielectric material. According to another example, the intermediate layer can be formed from a metal plate.

According to some embodiments, the feed arrangement for each antenna element includes a radio frequency (RF) coaxial line.

According to some embodiments, the feed arrangement for each antenna element includes an embedded microstrip feed line arranged within the bottom dielectric substrate.

According to some embodiments, the feed arrangement for each antenna element includes an microstrip feed line arranged on the bottom substrate underside of the bottom dielectric substrate.

According to some embodiments, the feed arrangement for each antenna element includes a strip feed line arranged within the bottom dielectric substrate.

For the purpose of the present application the term “microstrip line feed line” is referred to a type of electrical transmission line having a single conductor trace on one side of a dielectric substrate and a single ground plane on the opposite side. The term “stripline feed line” is referred to a type of electrical transmission line with a single conductor trace, which is sandwiched between two parallel ground planes. In this structure the insulated material is made up of two dielectric layers. The central conductor should not necessary be equally spaced between the ground planes. Generally, a dielectric material above the central conductor may be different than the dielectric material below the central conductor. The term “embedded microstrip feed line” is referred to a feed line that is similar to the microstrip feed line, however the conductor trace (signal line) is embedded in a dielectric. In this structure the dielectric is made up of two dielectric layers.

According to an embodiment, the feed arrangement includes a grounded layer of conductive material arranged within the bottom dielectric substrate. The grounded layer for each antenna element can include a corresponding opening arranged under the bottom feeding patch. According to this embodiment, the feed arrangement includes a plurality of microstrip feed lines arranged for each antenna element correspondingly within the bottom dielectric substrate to provide capacitive coupling for transferring RF energy between the micro strip feed line and the bottom feeding patch through the opening in the grounded layer.

According to some embodiments, the phased array antenna comprises a plurality of bottom encompassing vias connecting the conductive lower bottom coating mounted on the bottom substrate underside to the upper bottom coating mounted on the bottom substrate upper side.

According to some embodiments, the phased array antenna also comprises a plurality of top encompassing vias connecting the conductive lower top coating mounted on the top substrate underside to the upper top coating mounted on the top substrate upper side.

According to some embodiments, the phased array antenna also comprises a plurality of separating vias passing through at least the bottom dielectric substrate, the intermediate layer, and the top dielectric substrate. The separating vias connect the conductive lower bottom coating mounted on the bottom substrate underside to the upper top coating mounted on the top substrate upper side.

According to another general aspect, there is provided a novel antenna element having a vertically stacked structure. The antenna element comprises:

a bottom dielectric substrate, the bottom dielectric substrate having a bottom substrate underside having a lower bottom conductive coating adhesively bound thereto, and a bottom substrate upper side having an upper bottom conductive coating adhesively bound thereto;

an antenna element conductive shell extending away from the bottom substrate upper side and connected to said upper bottom conductive coating, the antenna element conductive shell having a lumen to define an antenna element cavity having an antenna element aperture;

a feeding radiator backed by the cavity, the feeding radiator including a bottom slot arranged within the cavity in said upper bottom conductive coating to define a bottom feeding patch encompassed by the bottom slot;

a top dielectric substrate common for all the antenna elements, said top dielectric substrate having a top substrate underside having a lower top coating adhesively bound thereto, and a top substrate upper side having an upper top coating adhesively bound thereto, said lower top coating being connected to said antenna element conductive shell;

a parasitic radiator backed by the cavity being disposed over and spaced apart from said feeding radiator, and parasitically coupled to said feeding radiator, said parasitic radiator including a top slot in said upper top coating to define a top radiating patch encompassed by the top slot; and

an antenna element feed arrangement coupled to the feeding radiator and operable to provide radio frequency energy thereto.

According to some embodiments, shapes of the bottom feeding patch, the top radiating patch, antenna element aperture, and a cross-section of the antenna element conductive shell are selected from a round shape, oval shape, ring shape, polygonal shape, and D-shape.

The phased array antenna and the antenna element of the present invention has many of the advantages of the prior art techniques, while simultaneously overcoming some of the disadvantages normally associated therewith.

The phased array antenna of the present invention can generally be configured to operate in a broad band within the frequency range of about 100 MHz to 100 GHz.

The phased array antenna according to the present invention may be efficiently manufactured. The printed circuit part of the antenna elements can, for example, be manufactured by using printed circuit techniques.

The installation of the antenna elements and antenna array of the present invention is relatively quick and easy.

The phased array antenna and antenna element according to the present invention is of durable and reliable construction.

The phased array antenna according to the present invention may be readily conformed to complexly shaped surfaces and contours of a mounting platform.

There has thus been outlined, rather broadly, the more important features of the invention so that the detailed description thereof that follows hereinafter may be better understood, and the present contribution to the art may be better appreciated. Additional details and advantages of the invention will be set forth in the detailed description.

DETAILED DESCRIPTION OF EMBODIMENTS

The principles and operation of a phased array antenna and the antenna elements according to the present invention may be better understood with reference to the drawings and the accompanying description. It should be understood that these drawings are given for illustrative purposes only and are not meant to be limiting. It should be noted that the figures illustrating various examples of the system of the present invention are not to scale, and are not in proportion, for purposes of clarity. It should be noted that the blocks as well other elements in these figures are intended as functional entities only, such that the functional relationships between the entities are shown, rather than any physical connections and/or physical relationships. The same reference numerals and alphabetic characters will be utilized for identifying those components which are common in the device and its components shown in the drawings throughout the present description of the invention.

Referring toFIG. 1A, a schematic side cross-sectional view of a phased array antenna10is illustrated, according to one embodiment of the present invention. The phased array antenna10includes a plurality of antenna elements11sharing a common conductive ground plane12. The common conductive ground plane12is common for all the antenna elements11. The antenna elements11are spaced apart at a predetermined distance from each other which is required either to eliminate the grating lobes from the visible zone or at least to adequately suppress the relative power of the grating lobes with respect to the main beam.

The phased array antenna10also includes a common conductive shell13for all the antenna elements that is electrically (e.g., galvanically) coupled to the common conductive ground plane12. The common conductive shell13extends away from conductive ground plane12to encompass the plurality of the antenna elements11. The common conductive shell13and the common conductive ground plane together define a common cavity14having a common aperture15.

The phased array antenna10also includes a common dielectric superstrate layer16disposed over the common cavity14. As shown inFIG. 1A, the common dielectric superstrate layer16is arranged at the common aperture15, i.e. within the common cavity14. However, when desired, the superstrate layer16can completely overlay the aperture15and be mounted on walls131A of the common conductive shell13.

According to an embodiment, a gap in the common cavity14between the antenna elements11and the superstrate layer16is filled with a dielectric material (not shown) having a dielectric permittivity ∈gequal to or greater than the dielectric permittivity of air. In such a case, the dielectric material can be made of a solid material forming a support for supporting the superstrate layer16.

Furthermore, the phased array antenna10also includes a beam steering system17coupled to the plurality of the antenna elements11and configured for steering an energy beam produced by the phased array antenna10. The beam steering system is a known system that can, inter alia, include such components as a feeding arrangement shown schematically by a reference numeral171and configured for feeding the antenna elements11. The beam steering system also includes T/R modules (not shown), Digital signal processing (DSP) driven switches (not shown), connectors, and other components required to control steerable multi-beams.

It should be noted that the phase array antenna structure10can be implemented in various ways. As shown inFIG. 1A, the inner walls131A of the common conductive shell13of the phased array antenna10are straight, i.e. perpendicular to the common conductive ground plane12; however other configurations are also contemplated.

For example,FIGS. 1B and 1Cillustrate, correspondingly, outwardly tapered and inwardly tapered walls of the common conductive shell13from the common conductive ground plane12towards the common aperture15of the common cavity14.

For example, angles of the inwardly tapered wall and outwardly tapered wall are in the range of about 0 degrees to about 30 degrees. According to an embodiment, all of the walls131B and131C may be tapered. According to another embodiment (not shown), only a portion of the walls131B and131C may be tapered. When desired, distinct portions of the walls131B and131C may have different tapers.

The antenna elements11of phased array antenna10can be arranged in columns and rows, however other arrangements are also contemplated. A shape of a front of the common aperture15can take any desired shape, including, but not limited to, a circular shape, oval shape, D-shape polygonal shape (e.g., triangular, square, rectangular, quadrilateral, pentagon, hexagonal, etc) and other shapes. Accordingly, the number of the rows in which the antenna elements11are arranged can be equal to the number of the columns. Alternatively, the numbers of the rows and the columns in the antenna array can be different. Moreover, the number of the antenna elements11in neighboring rows can be either equal or different. Moreover, the arrangement of the antenna elements11in the array can be either regular or staggered, thereby forming a rectangular or triangular lattice.

It should still further be noted that the phase array antenna10may be used as a single radiator in conjunction with a transceiver device, or it may be combined together with additional antenna arrays to form a larger array antenna. And it should still further be noted that although the front side18of the array antenna shown inFIGS. 1A-1Chas a planar shape, when desired, the array antenna may alternatively have a curved or undulated face.

A height Lgof the gap in the common cavity14between the common superstrate layer16and a top of the plurality of antenna elements11depends on the desired deflection angles θ of the radiation beam. The deflection is calculated from an axis (not shown) perpendicular to the antenna aperture.

According to an embodiment, the height Lgof the gap can be obtained by

Lg≈{λg⁡(x+n2),where⁢⁢0.6≤x≤0.65for⁢⁢0⁢°≤θ≤15⁢°λg⁡(0.01⁢⁢θ+0.327+0.6⁢⁢n),for⁢⁢15⁢°<θ≤45⁢°y⁢⁢λg,where⁢⁢0.45≤y≤0.5for⁢⁢45⁢°<θ≤70⁢°
where λg=λ0/√∈g, and λ0is the wavelength corresponding to the central operation frequency of the phased array antenna, ∈gis the dielectric permittivity of the dielectric material filling the gap in the common cavity14, θ is the required deflection angle (in degrees), and n=0, 1, 2, . . . It should be noted that the case when n=0 is preferred.

According to an embodiment, a thickness of the common dielectric superstrate layer16is uniform and complies with a relationship LSL≈λSL(0.2+n/2), where λSL=λ0/√∈SL, and λ0is the wavelength corresponding to the central operation frequency of the phased array antenna, ∈SLis the dielectric permittivity of the common dielectric superstrate layer16, and n=0, 1, 2, . . . It should be noted that the case when n=0 is preferred.

According to another embodiment, a thickness of the common dielectric superstrate layer16near walls of the common conductive shell13is different than the thickness of the common dielectric superstrate layer16at its center. Side surfaces of the common dielectric superstrate layer16can, for example, be biplanar surfaces, biconcave surfaces, plano-concave surfaces, and convex-concave surfaces.

According to an embodiment, the common superstrate layer16is made from a heat insulating material. According to an embodiment, an outer surface of the common superstrate layer16can be covered with a heat insulating material (not shown).

It was found that the configuration and parameters of the antenna element11and the phased array antenna structure10significantly affect their performance. Several examples of such dependencies will be illustrated herein below.

A computer simulation analysis was carried out in order to determine the effect of the presence of the common dielectric superstrate layer16together with the common conductive shell13on various characteristics of the phase array antenna shown inFIG. 1A. The simulations were carried out for an example of the phase array antenna shown inFIG. 13. According to this example, the array antenna includes 40 antenna elements11having a rectangular shape with the side of the common aperture15equal to 9.7λ0and 2.1λ0. The antenna elements11are arranged in two rows in H-plane and with 20 antenna elements in each row arranged in E plane. The distance Del-Hbetween the antenna elements in H plane was set to λ0/2, whereas the distance Del-Ebetween the antenna elements in E plane was set to 0.47λ0. The distance Del-sh-Hbetween the edges of the antenna elements arranged in the two rows to the common conductive shell13in H plane was set to 0.65λ0, whereas the distance Del-sh-Ebetween the edges of the edging elements (first and last) in the row to the common conductive shell13in E plane was set to 0.23λ0. The dielectric permittivity ∈gof the dielectric material filling the gap in the common cavity (14inFIG. 1A) was set to 1. The dielectric permittivity ∈SLof the common dielectric superstrate layer (16inFIG. 1A) was set to 4. The height Lgof the gap in the common cavity (14inFIG. 1A) between the common superstrate layer (16inFIG. 1A) and a top of the plurality of antenna elements (11inFIG. 1A) was varied between 0.13λ0and 0.93λ0. The thickness LSLof the common dielectric superstrate layer16was set to 0.2λSLwhere λSL=λ0/√∈SL.

FIG. 9shows the effect of the presence of the common dielectric superstrate layer16together with the common conductive shell13shown inFIG. 1Aon the array pattern variation in E plane for the scanning angle of 40 degrees. The height Lgof the gap in the common cavity14between the common superstrate layer16and a top of the plurality of antenna elements is set to on optimal value of 0.73λ0for the scanning angle of 40 degrees.

It was found that the antenna array has an optimal gain for the scanning angle of 40 degrees when the height Lgof the gap in the common cavity14between the common superstrate layer16and a top of the plurality of antenna elements is set to 0.73λ0. A dotted line91corresponds to a radiation pattern of the phase antenna array without the superstrate layer16and without the common conductive shell13. A continuous line92corresponds to a radiation pattern of the phase antenna array having the superstrate layer16and the common conductive shell13. As can be seen, the presence of the superstrate layer and common conductive shell causes peak gain improvement by 1 dB. Moreover, in the presence of the superstrate layer and common conductive shell, the width of the beam is wider and the degradation in side lobe level is observed at angles in the range of −20 degrees to −90 degrees.

FIGS. 10A-10Cshow the effect of the presence of the common dielectric superstrate layer16together with the common conductive shell13shown inFIG. 1Aon the array pattern for variation of a peak gain as a function of the height Lgof the gap in the common cavity (14inFIG. 1A) between the common superstrate layer (16inFIG. 1A) and a top of the plurality of antenna elements (11inFIG. 1A) at various deflection angles.

Referring toFIG. 10A, the dependence of the peak gain versus the height Lgis shown when the deflection angle equals 0 degrees, i.e. no deflection. A dotted line101corresponds to a peak gain variation of the phase antenna array without the superstrate layer16and without the common conductive shell13, whereas a continuous line102corresponds to a peak gain variation of the phase antenna array having the superstrate layer16and the common conductive shell13. As can be seen, the presence of the superstrate layer and common conductive shell causes peak gain improvement when the height Lgof the gap is in the range of 0.38λ0to 0.72λ0. The optimal height Lgof the gap for this case is equal to 0.6λ0, and the improvement of the peak gain for this case is 2.7 dBi that is equal to the increase in the system range by 36%.

Referring toFIG. 10B, the dependence of the peak gain versus the height Lgis shown when the deflection angle equals 30 degrees. A dotted line103corresponds to a peak gain variation of the phase antenna array without the superstrate layer16and without the common conductive shell13, whereas a continuous line104corresponds to a peak gain variation of the phase antenna array having the superstrate layer16and the common conductive shell13.

As can be seen, the presence of the superstrate layer and common conductive shell causes peak gain improvement when the height Lgof the gap is in the range of 0.28λ0to 0.92λ0. The optimal height Lgof the gap for this case is equal to 0.63λ0, and the improvement of the peak gain for this case is 1.2 dBi that is equal to the increase in the system range by 15%.

Referring toFIG. 10C, the dependence of the peak gain versus the height Lgis shown when the deflection angle equals 45 degrees. A dotted line105corresponds to a peak gain variation of the phase antenna array without the superstrate layer16and without the common conductive shell13, whereas a continuous line106corresponds to a peak gain variation of the phase antenna array having the superstrate layer16and the common conductive shell13.

As can be seen, the presence of the superstrate layer and common conductive shell causes peak gain improvement when the height Lgof the gap is in the range between 0.19λ0and 0.93λ0. The optimal height Lgof the gap for this case is equal to 0.8λ0, and the improvement of the peak gain for this case is 1.2 dBi that is equal to the increase in the system range by 15%.

FIG. 11shows the dependence of the beam width versus the height Lgwhen the deflection angle equals 0 degrees, i.e. no deflection (curve1011), 30 degrees (curve1012) and 45 degrees (curve1013).

As can be seen from the behavior of curve1011, the changes of the height Lghave insignificant effect onto the beam width for the case when the deflection angle is 0 degrees. In particular, when the height Lgof the gap increases from 0.46λ0to 0.93λ0the beam width varies in the range of 5.2-5.4 degrees (i.e., by 4%). It should be noted that for the case of the phase antenna array without the superstrate layer16and without the common conductive shell13the beam width equals 5.3 degrees.

As can be seen from the behavior of curve1012, the changes of the height Lgof the gap have greater effect onto the beam width when the deflection angle is 30 degrees. In particular, when the height Lgof the gap increases from 0.46λ0to 0.93λ0the beam width varies in the range of 6.4-6.8 degrees (i.e., by 6%). It should be noted that for the case of the phase antenna array without the superstrate layer16and without the common conductive shell13the beam width equals 6.2 degrees. As can be seen, the presence of superstrate layer16and the common conductive shell13results in a wider beam. It should be noted that the peak gain is also increased when the height Lgof the gap increases from 0.46λ0to 0.93λ0, that enhances the performance of the array antenna by covering a greater area.

As can be seen from the behavior of curve1013, the changes of the height Lgof the gap have the most significant effect onto the beam width when the deflection angle is 45 degrees. In particular, when the height Lgof the gap increases from 0.46λ0to 0.93λ0the beam width varies in the range of 7-8.7 degrees (i.e., by 24%). It should be noted that for the case of the phase antenna array without the superstrate layer16and without the common conductive shell13the beam width equals 7.6 degrees. As can be seen, for the case when the deflection angle is 45 degrees, the optimal height Lgof the gap is 0.86λ0. it should be noted that the increase of the beam width occurs concurrently with the increase of the peak gain that enhances the performance of the array antenna by covering a greater area.

FIGS. 12A-12Cshow the effect of the presence of the common dielectric superstrate layer16together with the common conductive shell13shown inFIG. 1Aon the array pattern for variation of a peak gain in E plane as a function of the deflection angle at various heights Lgof the gap in the common cavity (14inFIG. 1A) between the common superstrate layer (16inFIG. 1A) and a top of the plurality of antenna elements (11inFIG. 1A).

Referring toFIG. 12A, the dependence of the peak gain versus the deflection angle is shown when the height Lgis equal to λ0/2. A dotted line121corresponds to a peak gain variation of the phase antenna array without the superstrate layer16and without the common conductive shell13, whereas a continuous line122corresponds to a peak gain variation of the phase antenna array having the superstrate layer16and the common conductive shell13. As can be seen, the presence of the superstrate layer and common conductive shell causes improvement of the peak gain for the deflection angles in the range of 0 degrees to 38 degrees and 40 degrees to 70 degrees by about 1 dB to 1.7 dB that corresponds to the increase in the system range by about 12% to 22%. Accordingly, in order to obtain the maximum peak gain performance for this antenna for the deflection angles in the range of 45°-70° one has to choose the height Lgthe gap to be equal to λ0/2.

Referring toFIG. 12B, the dependence of the peak gain versus the deflection angle is shown when the height Lgis equal to 0.63λ0. A dotted line123corresponds to a peak gain variation of the phase antenna array without the superstrate layer16and without the common conductive shell13, whereas a continuous line124corresponds to a peak gain variation of the phase antenna array having the superstrate layer16and the common conductive shell13. As can be seen, the presence of the superstrate layer and common conductive shell causes improvement of the peak gain for the deflection angles in the range of 0 degrees to 70 degrees. The maximal improvement of the peak gain by up to about 2.5 dB is observed at relatively small deflection angles in the range of 0 degrees to 5 degrees that corresponds to the increase in the system range by about 30%. In the range of the deflection angles of 55 degrees-65 degrees the peak gain improvement is about 0.25 dBi that corresponds to the increase in the system range by about 3%. Accordingly, in order to obtain the maximum peak gain performance for this antenna for the deflection angle of 30° one has to choose the height Lgthe gap to be equal to 0.63λ0.

Referring toFIG. 12C, the dependence of the peak gain versus the deflection angle is shown when the height Lgis equal to 0.8λ0. A dotted line125corresponds to a peak gain variation of the phase antenna array without the superstrate layer16and without the common conductive shell13, whereas a continuous line126corresponds to a peak gain variation of the phase antenna array having the superstrate layer16and the common conductive shell13. As can be seen, the presence of the superstrate layer and common conductive shell causes a decrease in the peak gain for the deflection angles in the range of 0 degrees to 24 degrees, increases the peak gain for the deflection angles in the range of 25 degrees to 55 degrees, and does not affect the peak gain for the deflection angles in the range of 55 degrees to 70 degrees. The maximal improvement of the peak gain by up to about 1.2 dB is observed at the deflection angle of about 45 degrees that corresponds to the increase in the system range by about 15%. Accordingly, in order to obtain the maximum peak gain performance for this antenna for the deflection angle of 45° one has to choose the height Lgthe gap to be equal to 0.8λ0. For the deflection angles less than about 25° the antenna with such a configuration will not be operable.

The antenna elements11of phase array antenna structure20can be implemented in various ways.

Referring toFIG. 2A, a schematic side cross-sectional fragmentary view of the phased array antenna ofFIG. 1Ais illustrated with an enlarged side cross-sectional view of the antenna elements11, according to one embodiment of the present invention.

According to this embodiment, each antenna element11has a vertically stacked structure. The term “vertically stacked” is used herein for the purpose of description of a relationship between the components of the antenna element11, rather than for description of orientation of the antenna structure in space. It should be noted that only two antenna elements closest to the common conductive shell13are shown in the selected fragment inFIG. 2A.

Starting the description of the antenna element11from the bottom, the vertically stacked structure of antenna element11includes a bottom dielectric substrate111having a bottom substrate underside112and a bottom substrate upper side113.

According to one embodiment, the dielectric substrate111is common for all the antenna elements11. According to another embodiment, at least a part of the antenna in elements11has individual (not shown) dielectric substrates111separated from each other.

The dielectric substrate111is provided with two-side thin metallic coatings (dads). As will be described herein below, appropriate etching of these coatings defines the antenna element configuration and properties.

According to the embodiment shown inFIG. 2A, the common conductive ground plane (12inFIGS. 1A-1C) of the phased array antenna10is formed from two metallic bottom coatings (a lower bottom coating1121and an upper bottom coating1131) adhesively bound to the bottom substrate underside112and to the bottom substrate upper side113, correspondingly. It should be noted that the terms “bottom” and “top” are used herein for the purpose of description of a relationship between the components of the phased array antenna, rather than for description of orientation of the antenna structure in space. The lower bottom coating1121and the upper bottom coating1131are grounded, thereby forming the ground plane (12inFIGS. 1A-1C).

There is a wide choice of materials suitable for the lower and upper bottom coatings1121and1131. These coatings can generally be made of conductive material. Examples of conductive materials suitable for the bottom coatings1121and1131include, but are not limited to, copper, silver, gold and their alloys. The coatings1121and1131are selected to be rather thin, such that their thickness is much less than the free-space operating wavelength.

The antenna element11also includes an antenna element conductive shell114extending away from the bottom substrate upper side113and connected to the upper bottom coating1131arranged on the bottom substrate upper side113. The antenna element conductive shell114has a lumen that defines an antenna element cavity115with an antenna element aperture116. As can be understood the antenna element cavity115is formed by the upper bottom coating1131and the antenna element conductive shell114. A transverse cross-section of the antenna element conductive shell114(that defines the shape of the aperture116), can generally have any desired shape, including, but not limited to, a circular shape, oval shape, D-shape polygonal shape (e.g., triangular, square, rectangular, quadrilateral, pentagon, hexagonal, etc) and other shapes. When the antenna element conductive shell114has a tubular shape, a diameter of antenna element cavity115can, for example, be in the range of 0.1λ0to 0.6λ0, where λ0is the wavelength corresponding to the central operation frequency. Such a relatively small contour of the cavity115is essential for providing great deflection angles for radiation.

The conductive shell114can, for example, be formed from aluminum to provide a lightweight structure, although other materials, e.g., copper, zinc plated steel, can also be employed. According to some embodiments, antenna element cavity115can be filled with a dielectric material having a dielectric permittivity greater than the dielectric permittivity of air.

The antenna element11also includes a feeding radiator1160printed on the bottom substrate upper side113and backed by the cavity115. To form the feeding radiator1160, the upper coating1131has a bottom slot1132defining a bottom feeding patch1133encompassed by the bottom slot1132.

According to one embodiment, the bottom slot1132is a circular slot (in the shape of a circular ring) defining a circular bottom patch printed on the bottom substrate upper side113. However, generally, a shape of the bottom slot1132and the bottom patch1133may have any desired shape, including, but not limited to, an oval shape, a D-shape polygonal shape (e.g., triangular, square, rectangular, quadrilateral, pentagon, hexagonal, etc) and other shapes.

The bottom patch1133can, for example, be etched on the surface of the dielectric substrate113by using a conventional photolithography technique; however other techniques can also be used. The bottom slot1132separates the bottom patch1133from the common conductive ground plane12. When coupled to a suitable feed, the bottom patch1133can be used for radiating electromagnetic energy. Preferably, but not mandatory, the circular bottom feeding patch1133is centered at the bottom of the antenna element cavity115. When the bottom patch1133has a circular shape, a diameter of the circular patch1133can, for example, be in the range of 0.05λ0to 0.35λ0, where λ0is the wavelength corresponding to the central operation frequency. This relatively small radiation element contour is essential for providing great deflection angles for radiation.

It should be noted that the bottom slot1132can also be used for radiating electromagnetic energy, mutatis mutandis. A width of the bottom radiating slot1132can, for example, be in the range of 0.01λ0to 0.15λ0.

The antenna element11further includes a parasitic radiator1170backed by the cavity115and parasitically coupled to the feeding radiator1160. To form parasitic radiator1170, the antenna element11includes a top dielectric substrate117common for all the antenna elements11in the phased array antenna10. The top dielectric substrate117has a top substrate underside118and a top substrate upper side119. The top dielectric substrate117is disposed over the antenna element cavity115, and has two conductive top coatings (a lower top coating1181and an upper top coating1191) adhesively bound to the top substrate underside118and to the bottom substrate upper side119, correspondingly. The conductive coatings1181and1191can, for example, be formed from copper, gold, silver, etc. When desired their alloys can also be used.

The antenna element conductive shell114is connected to the lower top coating1181. According to the embodiment shown inFIG. 2, the lower top coating1181has an area free from metal which faces the antenna element aperture116and repeats a contour of its perimeter. For example, when the antenna element aperture116has a circular shape, this free of metal area has also the same circular shape.

It should be noted that a cross-sectional size of the antenna element aperture116(i.e., the area free from the metal in the lower top coating1181) may be equal to or less than the cross-sectional size of the antenna element conductive shell114.

FIG. 2Billustrates a schematic transverse cross-sectional fragmentary view through A-A plane of the phased array antenna shown inFIG. 2A. This A-A plane corresponds to the plane of the top substrate underside118.

Referring toFIGS. 2A and 2Btogether, the upper top coating1191has a top slot1192defining a top radiating patch1193printed on the top substrate upper side119in the upper top coating1191. Alternatively, when desired, a top slot and a top radiating patch (not shown) can be printed within the antenna element cavity115on the top substrate underside118of the top dielectric substrate117in the lower top coating1181.

Generally, the top slot1192and the top patch1193can have any desired shape. However, when the bottom slot1132has a circular ring shape, preferably, but not mandatory, then the top slot1192would also have a circular ring shape. Likewise, when the bottom patch1133has a circular shape, preferably, but not mandatory, then the top patch1193would also have a circular shape.

The top radiating patch1193is disposed over and spaced apart from the feeding radiator1160at predetermined distance h, and is parasitically coupled either to the bottom patch1133or to the circular bottom slot1132. When the top patch1193has a circular shape, a diameter of the patch1193can, for example, be in the range of 0.05λ0to 0.35λ0, whereas a width of the circular bottom slot1192can, for example, be in the range of 0.01λ0to 0.15λ0, where λ0is the wavelength corresponding to the central operation frequency. A ratio between a maximal horizontal cross-sectional dimension of the antenna element cavity115and the maximal dimension of the top radiating patch1193can, for example, be in the range of 0.5 to 0.95. Turning back toFIG. 2A, the antenna elements11are fed by the feed arrangement171. As shown inFIG. 2A, the feed arrangement171includes a plurality of radio frequency (RF) coaxial lines (vertical probes), each coaxial line having an inner conductor21and an outer conductor22. The inner conductor21is extended through an opening in the bottom dielectric substrate111and in the conductive ground plane12, and is electrically (e.g., galvanically) connected to the bottom feeding patch1133at a feed point23for providing radio frequency energy thereto. When required, the outer conductor22is connected to the ground plane12.

The feed point23is located within the bottom patch1133; however other implementations are also contemplated. Preferably, the feed point23is arranged at a certain distance from the center C of the circular bottom patch1133, required to provide optimal feed impedance matching and mitigation of cross-pole components of the linearly polarized beam excitation. For example, the distance between the center C of the circular bottom patch1133and the feed point23can be in the range of 0.02λ0to 0.15λ0, where λ0is the wavelength corresponding to the central operation frequency.

It should be appreciated that the antenna element described above has the ability to operate in any polarization chosen. This implies that the antenna element can provide vertical, horizontal or circular polarized radiation. When desired, the radiation can be polarized to 45 degrees or any other polarization desired. The reason is that the polarization is determined by the position of the feed point23with respect to the printed circular bottom patch1133. When the patch1133is symmetric the feed point23can be located in any position desired.

If circular polarization is desired, two feed points (not shown) on the bottom patch1133are fed by two orthogonally phased (90° shifted) signals.

Another implementation for providing circular/elliptical polarization can be a single point external feed with inherent splitter and phase shift that can be implemented on the surface of the patch1133for double-point patch excitation.

Still another implementation for providing circular/elliptical polarization with the antenna element described above can be a single point feed radiating element configured for providing circular/elliptical polarization. In particular, circular/elliptical polarization can be archived by a suitable configuration of the radiating patch. Examples of the radiating patch providing circular/elliptical include, but are not limited to, a triangular shaped patch, a rectangular shaped, a mainly circular patch which has a slightly perturbed circular shape, etc.

According to an embodiment of the present invention, the antenna element11includes an intermediate layer1120sandwiched between the bottom dielectric substrate111and the top dielectric substrate117. The intermediate layer1120is a structural spacer providing a desired vertical separation and support to the bottom dielectric substrate111and the top dielectric substrate117.

According to one embodiment, the intermediate layer1120is formed from a solid dielectric material having a predetermined dielectric permittivity. According to an embodiment, the intermediate layer1120may be coated, with a two-side metallic clad or with a one-side metallic clad on an upper or bottom sides. According to another embodiment, the intermediate layer1120may be uncoated, i.e., totally stripped of its two-side metallic clad. The layer1120is sieved by a through hole, which can be metallized on an inner surface24by a metal clad (e.g., copper, gold, etc.), thereby to form the antenna element cavity115which backs and encompasses the stacked radiating pair formed from the feeding radiator1160and the parasitic radiator1170.

The dielectric constant value of the bottom dielectric substrate111, the intermediate layer1120and the top dielectric substrate117can differ in a broad range of values. For example, the dielectric constants of the bottom dielectric substrate111and the top dielectric substrate117can be between 1 and 10, whereas the dielectric constant of the intermediate layer1120can be between 1 and 100. The values of the dielectric constant are determined by the desired operation frequency, bandwidth, matching optimization, as well as by the dimensions of the antenna element. The relatively higher dielectric constant value for the intermediate layer allows for intra-element coupling mitigation for the antenna array. A thickness of the bottom dielectric substrate111, the intermediate layer1120and the top dielectric substrate117is determined by the operating central frequency, bandwidth and structural constraints. For example, the thickness of the bottom dielectric substrate111can be in the range of 0.01λ0to 0.2λ0, the thickness of the top dielectric substrate117can be in the range of 0.01λ0to 0.15λ0, and the thickness of the intermediate layer1120can be in the range of 0.05λ0to 0.3λ0, where λ0is the wavelength corresponding to the central operation frequency.

According to some embodiments, the antenna of the present application includes one or more vias that may connect conductive coatings from one surface of the dielectric substrates to other surface(s).

For example, the bottom feeding patch1133can be galvanically and electromagnetically grounded by an electrically conductive via1123at a central loci point C. The central loci point C can also be connected to the grounded lower bottom coating1121. This provision can enhance the polarization quality and mitigates the cross-pole components of the excitation.

A computer simulation analysis was carried out in order to study the effect of the presence of the electrically conductive via1123on the resonant frequency of the antenna element. Referring toFIG. 7, exemplary graphs depicting the frequency dependence of the increment of the cross-polarization level on the antenna element performance is shown for the antenna element shown inFIGS. 2A and 2B. The increment is the difference between the cross-polarization levels in the cases of the absence and presence of the electrically conductive via1123.

For example, in the range of the normalized frequency F/F0from 0.97 to 1.03 (±3% of the normalized frequency), the providing of the electrically conductive via1123results in the increase of the cross-polarization level between 3.5 dB and 13 dB.

Referring toFIGS. 2A and 2Btogether, the antenna of the present application further includes a plurality of bottom encompassing vias31connecting the conductive lower bottom coating1121(i.e., ground plane) mounted on the bottom substrate underside112to the upper bottom coating1131mounted on the bottom substrate upper side113. Likewise, the antenna of the present application further includes a plurality of top encompassing vias32connecting the conductive lower top coating1181(i.e., ground plane) mounted on the top substrate underside118to the upper top coating1191mounted on the top substrate upper side119.

The vias31encompass the feeding radiator1160and form an equivalent (virtual) coaxial-type ground cavity around it, thereby preventing energy leakage through the bottom dielectric substrate111. Likewise, the vias32encompass the parasitic radiator1170and form an equivalent (virtual) coaxial-type ground cavity around it, thereby preventing energy leakage through the top dielectric substrate117. Thus, enhanced isolation between the antenna array elements (having common bottom and top dielectric substrates) is achieved. The number of the vias31and32depends, inter alia, on the operation frequency, antenna configuration and manufacturing tolerance.

For example, in the case of the circular bottom feeding patch1133and the circular top radiating patch1193, the number of the vias31and32that encircle these patches, can be in the range of 12 to 24. The encircling vias31are located at a predetermined distance from the central loci point C of the bottom feeding patch1133. Likewise, the encircling vias32are located at a predetermined distance from the central loci point D of the top patch1193.

The circle diameter for location of the vias31and32can, for example, be greater than the diameter of the patches1133and1193and the corresponding slot-rings outer diameter, but less than 0.5λ0to provide relatively dense arrangement of the antenna element and thereby to avoid grating lobes generated in the pattern of the radiated energy from the array. It was found by the Applicant that this condition may provide efficient beam deflection of the antenna radiation by up to 70° and even greater from the boresight.

It should be noted that the location of the encircling vias31and32and their placement scheme can differ from the patterns shown inFIGS. 2A and 2B. In particular, the location diameter should be greater than the corresponding patch and slot-ring outer diameter, but is not necessarily always greater than the diameter of the antenna element cavity115. Furthermore, a location diameter of the vias31may differ from the location diameter of the vias32. A distance between a pair of neighboring encircling vias31and between a pair of neighboring encircling vias32can, for example, be in the range of 0.005λ0to 0.2λ0.

When desired, either the vias31or the vias32can be extended to pass through the intermediate layer1120and through the top dielectric substrate117to connect the conductive lower bottom coating1131(i.e., the ground plane) mounted on the bottom substrate underside upper side113to the upper top coating1191mounted on the top substrate upper side119. In this case, the location diameter of the circle for location of such vias can, for example, be greater than the diameter of the patches1133, the diameter of the patches1193and the diameter of the antenna element conductive shell114.

According to an embodiment of the present application, the phased array antenna10includes a plurality of separating vias33passing through the intermediate layer1120and the top dielectric substrate117, and connecting the conductive upper bottom coating1131(i.e., ground plane) mounted on the bottom substrate upper side113to the upper top coating1191mounted on the top substrate upper side119. The purpose of the separating vias33is to reduce inter-elements coupling between the antenna elements11.

The separating vias33are arranged between the antenna elements11in two rows between each neighboring pair of the elements11. The separating vias33are arranged along planes E-E which are perpendicular to a plane F-F passing through the central loci points C and D. A number of the separating vias33in each row can, for example, be in the range of 4 to 12 (only four vias33are shown inFIG. 2B). A distance between the first and last vias33along the plane E-E can, for example be in the range of λ0/2. The separating vias33are located after the encircling vias31and32from the central loci points C and D. A distance between the central loci points C and D and the closest plane E-E is less than half of the distance between the central loci points of two close neighboring pair of the antenna elements11. A distance between two neighboring planes E-E can, for example, be in the range of 0.01λ0to 0.2λ0.

According to an embodiment of the present application, the phased array antenna10includes separating notches25and26arranged between the separating vias33and cut into the conductive lower top coating1181mounted on the top substrate underside118and into the upper top coating1191mounted on the top substrate upper side119, correspondingly. The separating vias33form a virtual cavity over the separating notches25and26. A length of the separating notches25and26can, for example, be in range of 0.1λ0to λ0/2, whereas a width of the separating notches25and26can, for example, be in the range of 0.01λ0to 0.3λ0.

A computer simulation analysis was carried out in order to determine the effect of the presence of the separating notches25and26and the separating vias33on the resonant frequency of the antenna element. Referring toFIG. 8, exemplary graphs depicting the frequency dependence of the mutual coupling in E-plane (Polarization Axis) between two neighboring antenna elements is shown for the antenna element shown inFIGS. 2A and 2B, in the cases of the absence and presence of the separating notches25,26and vias33. Specifically, a curve81corresponds to the case of the antenna element without the separating notches25,26and vias33, whereas curve82corresponds to the case having the separating notches25and26and the separating vias33. The simulation was performed for the configuration when the distance between the neighboring antenna elements in E-plane was set to 0.47λ0. The simulation was performed for the antenna elements without superstrate layer16.

As can be seen, the mutual coupling in E-plane between two neighboring antenna elements decreases by 2 dB to 11 dB in the range of the normalized frequency F/F0between 0.97 and 1.03 in the case of the presence of the separating notches25,26and vias33. The effect is most significant at F/F0=0.978.

A computer simulation analysis was carried out in order to find the effect of the presence of the common dielectric superstrate layer16on the resonant frequency of the antenna element. Referring toFIG. 6, exemplary graphs depicting the frequency dependence of the Voltage Standing Wave Ratio (VSWR) on the antenna element performance is shown for the antenna element shown inFIGS. 2A and 2B, in the cases of the absence and presence of the common dielectric superstrate layer. Specifically, curve61corresponds to the case of the antenna element without the superstrate layer, whereas curve62corresponds to the case when a height Lgof the gap in the common cavity14between the common superstrate layer16and the top of the plurality of antenna elements11equals λ0/2, and a thickness LSLof the common dielectric superstrate layer16is uniform and equals 0.2λ0.

As can be seen, a bandwidth of the antenna element of the antenna element of the present application is relatively wide even without the superstrate layer. In particular, a VSWR is less than 1.5:1 in the range of 0.986 to 1.017 that correspond to 3.1% of the normalized frequency F/F0, and less than 2.0:1 in the range of 0.978 to 1.036 that correspond to 5.8% of the normalized frequency.

In the case of the presence of the common dielectric superstrate layer16, the improvement of the antenna element performance can be seen when compared to the case without the superstrate layer. In particular, a VSWR is less than 1.5:1 in the range of 0.977 to 1.030 that correspond to 5.3% of the normalized frequency F/F0, and less than 2.0:1 in the range of 0.965 to 1.070 that correspond to 10.5% of the normalized frequency.

Referring toFIGS. 3A and 3Btogether, schematic side and top fragmentary in cross-sectional views of the phased array antenna30are illustrated, according to another embodiment of the present invention. The antenna30differs from the antenna10shown inFIGS. 2A and 2Bin the fact that the intermediate layer1120responsible for providing the desired distance between the staked radiating pair formed by the feeding radiator1160and the parasitic radiator1170, is formed from a metal plate. This provision can enhance the superior structural rigidity and stability of the antenna structure. To fabricate the intermediate layer1120, the metallic spacer plate is provided and then sieved by a through hole, thereby forming the antenna element cavity115. According to this embodiment, the intermediate layer can, for example, be formed from aluminum to provide a lightweight structure, although other materials, e.g., zinc plated steel, can also be employed. Another difference of the antenna30from the antenna10shown inFIGS. 2A and 2Bis in the fact that instead of the separating vias33and the separating notches25and26, the phased array antenna30includes other separating notches35cut into the metallic intermediate layer1120between each neighboring pair of the elements11perpendicular to a plane F-F passing through the central loci points C and D. The purpose of the separating notches35is to reduce the inter-elements coupling occurring through the open air above the radiating elements plane. A length of the separating notches35can, for example, be in the range of 0.1λ0to λ0/2. The cavity formed by the notches35can be filled with a dielectric material having a relatively high dielectric constant, e.g., alumina. Although the other separating notches35with a flat bottom are shown inFIG. 3A, when desired, the other separating notches35can have any suitable shape, for example, the other separating notches35can be V-shaped notches, U-shaped notches, etc.

Although the feed arrangement171shown inFIG. 2Ais in the form of a coaxial line (vertical probe), some other examples of implementations of the feed arrangement are shown herein below.

Referring toFIG. 4A, a cross-sectional fragmentary view of the antenna element11of the present invention utilizing another implementation of feed arrangement411is illustrated. According to this example, the feed arrangement411includes an embedded microstrip feed line421arranged within the bottom dielectric substrate111that provides capacitive coupling to transfer RF energy between the embedded microstrip feed line421and the bottom feeding patch1133. Each antenna element11in the phased array antenna can be fed by its own embedded microstrip feed line421. As shown inFIG. 4A, the embedded microstrip feed line421is arranged within the dielectric substrate111. In this case, the lower bottom coating1121has an area free from the metal under the embedded microstrip feed line421.

The embedded microstrip feed line421can be fed from a cable (not shown), and can be of such configuration that provides a suitable matching circuit between the cable and the patch. For example, the cable can be a semi-rigid coaxial cable that can be soldered to microstrip metal of the embedded microstrip feed line421. The microstrip metal can, for example, be a copper alloy.

FIG. 4Bshows a cross-sectional fragmentary view of the antenna element11of the present invention utilizing a feed arrangement412, according to another embodiment. The embodiment shown inFIG. 4Bdiffers from the embodiment shown inFIG. 4Ain the fact that the feed arrangement412includes a microstrip feed line422which is arranged on the bottom substrate underside112of the bottom dielectric substrate111. The microstrip feed line422can, for example, be adhesively bound to the bottom substrate underside112. The microstrip feed line422provides capacitive coupling to transfer RF energy between the microstrip feed line422and the bottom feeding patch1133.

Referring toFIG. 4C, a cross-sectional fragmentary view of the antenna element11of the present invention utilizing another implementation of feed arrangement413is illustrated according to still another embodiment. The embodiment shown inFIG. 4Cdiffers from the embodiment shown inFIG. 4Ain the fact that the feed arrangement413includes a strip feed line423rather than an embedded microstrip feed line. As shown inFIG. 4C, in this case the lower bottom coating1121fully covers the bottom substrate underside112, i.e. including the area under the strip feed line423.

It should be noted that the configurations of the antenna shown inFIG. 4AthroughFIG. 4Ccan provide linear polarization (either vertical or horizontal). Nevertheless, circular or elliptical polarization implementation can also be achieved by providing two embedded microstrip feed lines (not shown) arranged within the dielectric substrate111, which can be fed by two orthogonally phased (90° shifted) signals.

Still another implementation for providing circular/elliptical polarization with the antenna element described above can be a radiating element with a single strip feed line or a single microstrip feed line configured for providing circular/elliptical polarization. As described above, circular/elliptical polarization can be archived by a suitable configuration of the radiating patch. Examples of the radiating patch providing circular/elliptical include, but are not limited to, a triangular shaped patch, a rectangular shaped, a mainly circular patch which has a slightly perturbed circular shape, etc.

Referring toFIG. 5A, a cross-sectional fragmentary view of the antenna element11of the present invention utilizing still another implementation of feed arrangement511is illustrated. According to this embodiment, the antenna element11includes a grounded layer52of conductive material arranged within the bottom dielectric substrate111. The grounded layer52includes an opening53arranged under the bottom feeding patch1133. The feed arrangement511includes an embedded microstrip feed line541arranged within the bottom dielectric substrate111that provides capacitive coupling to transfer RF energy between the embedded microstrip feed line541and the bottom feeding patch1133through the opening53. In this case, the lower bottom coating1121has an area free from the metal under the embedded microstrip feed line541.

The amount of contactless coupling from the microstrip feed line541to the patch1133is determined by the shape, size and location of the opening53. It should be understood by a person versed in the art that the feed arrangements511may include more than one opening53. In addition, openings53may generally be of any shape, such as polygonal, circular and/or elliptical, that provides desired coupling between the microstrip feed line541and the patch1133.

FIG. 5Bshows a cross-sectional fragmentary view of the antenna element11of the present invention utilizing a feed arrangement512, according to another embodiment. The embodiment shown inFIG. 5Bdiffers from the embodiment shown inFIG. 5Ain the fact that the feed arrangement512includes a microstrip feed line542which is arranged on the bottom substrate underside112. The microstrip feed line542can, for example, be adhesively bound to the bottom substrate underside112of the bottom dielectric substrate111. The microstrip feed line542provides capacitive coupling to transfer RF energy between the microstrip feed line542and the bottom feeding patch1133through the opening53.

Referring toFIG. 5C, a cross-sectional fragmentary view of the antenna element11of the present invention utilizing another implementation of feed arrangement513is illustrated according to yet an embodiment. The embodiment shown inFIG. 5Cdiffers from the embodiment shown inFIG. 5Ain the fact that the feed arrangement513includes a strip feed line543rather than an embedded microstrip feed line. As shown inFIG. 5C, in this case the lower bottom coating1121fully covers the bottom substrate underside112, i.e. including the area under the strip feed line543. As such, those skilled in the art to which the present invention pertains, can appreciate that while the present invention has been described in terms of preferred embodiments, the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures systems and processes for carrying out the several purposes of the present invention.

The antenna of the present invention may be utilized in various inter systems, e.g., in communication within the computer wireless LAN (Local Area Network), PCN (Personal Communication Network) and ISM (Industrial, Scientific, Medical Network) systems.

The antenna may also be utilized in communications between a LAN and cellular phone network, GPS (Global Positioning System) or GSM (Global System for Mobile communication).

It is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

It is important, therefore, that the scope of the invention is not construed as being limited by the illustrative embodiments set forth herein. Other variations are possible within the scope of the present invention as defined in the appended claims. Other combinations and sub-combinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to different combinations or directed to the same combinations, whether different, broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of the present description.