Patent Description:
The present disclosure relates generally to circular patch antennas, and more particularly in one exemplary aspect to circular patch antennas for use with global navigation satellite system (GNSS) frequency bands.

Traditionally, antenna designs for use with GNSS frequency bands often utilize ceramic based materials to meet the performance-based requirements for these operating bands. However, these ceramic based materials are relatively heavy making their use less than desirable in applications in which mass is a design constraint. Additionally, ceramic based materials are relatively brittle which makes their there use with, for example, unmanned aerial vehicles (UAVs) less than desirable. Accordingly, ongoing trends in the development of antennas for use with, for example, UAVs has required the use of non-traditional materials that: (<NUM>) are lighter in weight to, inter alia, maximize the battery life for these UAVs; and (<NUM>) have increased impact-resistance, to improve the reliability of the antenna design. As a result, new technologies that address the deficiencies of prior ceramic-based antenna designs are now needed. Document <CIT> discloses a stacked patch antenna arrangement.

The present disclosure satisfies the foregoing needs by providing, inter alia, methods, apparatus and systems for the implementation of circular patch antennas that address some or all of the deficiencies recognized above. There is provided a circular patch antenna as set forth in the appended claims.

Other features and advantages of the present disclosure will immediately be recognized by persons of ordinary skill in the art with reference to the attached drawings and detailed description of exemplary implementations as given below.

The features, objectives, and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, wherein:.

Detailed descriptions of the various embodiments and variants of the apparatus and methods of the present disclosure are now provided. The figures depict embodiments of systems, circular patch antennas, or methods for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the scope of the claims.

Ongoing trends in the development of antennas for use with, for example, unmanned aerial vehicles (UAVs) has resulted in the development of non-traditional materials that: (<NUM>) are lighter in weight, to maximize the battery life for these UAVs; and (<NUM>) have increased impact-resistance, to improve the reliability of the antenna design. More recently, the assignee of the present disclosure has implemented a polymer dielectric substance fortified with ceramic particles that is utilized as an alternative to heavier and more brittle ceramics that have traditionally been used in these antenna designs. These polymer dielectric materials have been marketed under the name TERRABLAST® and are more than <NUM>% lighter than traditional ceramic antenna technologies and are impact resistant to withstand drops, falls and impacts making it ideal for applications such as, for example, UAVs, where the antenna's mechanical robustness following potential impacts is critical. This polymer dielectric material also has broader utility outside of antenna designs for use with UAV applications.

Referring now to <FIG>, a circular patch antenna <NUM> is shown and described in detail. The circular patch antenna <NUM> may be utilized as a GNSS patch antenna with sufficient frequency bandwidth to cover all L-band GNSS frequencies, while remaining manufacturable and relatively small-sized. Additionally, the resonant frequency of the circular patch antenna <NUM> may be reduced without sacrificing its phase and polarization performance characteristics. Additionally, through its incorporation of the aforementioned polymer dielectric material, the effective dielectric constant of the patch dielectric may be altered with geometric design changes to the underlying circular patch antenna <NUM> design while also improving upon its manufacturability and minimizing mass.

<FIG> is an exploded perspective view of a circular patch antenna <NUM> illustrating the various components that make up the antenna design. The circular patch antenna <NUM> includes a top dielectric patch <NUM> as well as a bottom dielectric patch <NUM> that may be manufactured from the aforementioned polymer dielectric fortified with ceramic particles. In some implementations, the top dielectric patch <NUM> and/or the bottom dielectric patch <NUM> may be manufactured from a ceramic or may be manufactured using other types of known dielectric materials. The circular patch antenna <NUM> also incorporate a plurality of distinct flexible printed circuit boards (PCBs). For example, these flexible PCBs may include a top patch flex PCB <NUM> that is positioned atop the top dielectric patch <NUM>, one or more middle patch flex PCB(s) <NUM>, <NUM> that are positioned between the top dielectric patch <NUM> and the bottom dielectric patch <NUM>, as well as a bottom ground flex PCB <NUM> that is positioned underneath the bottom dielectric patch <NUM>. These flex PCBs <NUM>, <NUM>, <NUM>, <NUM> may be manufactured from a polyimide material. The top flex PCB <NUM> forms the top patch metallization for the circular patch antenna <NUM>. One or more of the middle flex PCBs <NUM>, <NUM> form the middle patch metallization for the circular patch antenna <NUM>. Additionally, the use of two distinct middle flex PCBs <NUM>, <NUM> may serve to stabilize the performance of, for example, the top dielectric patch <NUM> across distinct circular patch antennas <NUM>. The bottom flex PCB <NUM> forms a ground plane for the circular patch antenna <NUM> that may stabilize the performance of the circular patch antenna <NUM> when the circular patch antenna <NUM> is mounted on, for example, non-planar or imperfectly planar surfaces. Although, the use of flexible PCBs <NUM>, <NUM>, <NUM>, <NUM> for the circular patch antenna <NUM> is exemplary and may be desirable in instances in which design constraints on the overall height of the circular patch antenna <NUM> dictate their usage, it would be readily appreciated by one of ordinary skill given the contents of the present disclosure that alternative implementations may utilize other types of traditional substrate materials including, for example, substrates made from FR-<NUM>, or other types of metallizations and substrate materials.

The circular patch antenna <NUM> may also include one or more solder pins <NUM>, <NUM>. As shown in <FIG>, the total number of solder pins <NUM>, <NUM> shown is four (<NUM>) to create a dual-feed circular patch antenna <NUM>, although it would be readily apparent to one of ordinary skill given the contents of the present disclosure that the number of solder pins <NUM>, <NUM> may be varied dependent upon specific design constraints. For example, a quad-feed circular patch antenna <NUM> may include eight (<NUM>) solder pins <NUM>, <NUM>. In some implementations, solder pins <NUM> may have a different length than solder pins <NUM>. For example, solder pins <NUM> may have a length of fifteen (<NUM>) mm, while solder pins <NUM> may have a length of eleven (<NUM>) mm. The difference in solder pin length may be necessary as some of these solder pins <NUM> may have to pass through both the top dielectric patch <NUM> and bottom dielectric patch <NUM>, while other ones of these solder pins <NUM> only need to pass through the bottom dielectric patch <NUM>.

As a brief aside, and referring to <FIG>, the feed apertures <NUM>, <NUM> as shown on the top of the circular patch antenna <NUM> are shown and described in detail. The inner feed apertures <NUM> are positioned about the centerline <NUM> of the circular patch antenna <NUM> at a diameter D2. The outer feed apertures <NUM> are positioned about the centerline <NUM> of the circular patch antenna <NUM> at a diameter D1. In some implementations, solder pins <NUM> may be received within respective ones of the inner feed apertures <NUM>, while solder pins <NUM> may be received within respective ones of the outer feed apertures <NUM>, albeit underneath the top dielectric patch <NUM> as shown in <FIG>. However, in some implementations, this arrangement may be reversed such that solder pins <NUM> may be received within respective ones of the outer feed apertures <NUM>, while solder pins <NUM> may be received within respective ones of the inner feed apertures <NUM>. Referring now to <FIG>, solder pins <NUM> pass through the top flex PCB <NUM>, the top dielectric patch <NUM>, through both the middle flex PCBs <NUM>, <NUM>, the bottom dielectric patch <NUM>, and the bottom flex PCB <NUM>. In some implementations, solder pins <NUM> are positioned atop the lower flex PCB <NUM> where they protrude therethrough, before passing through the bottom dielectric patch <NUM>, and the bottom flex PCB <NUM>. In some implementations, solder pins <NUM> do not pass through both of the middle flex PCBs <NUM>, <NUM>; rather they only pass through the lower middle flex PCB <NUM>. Referring again to <FIG>, the circular patch antenna <NUM> may also be secured to an end user PCB (<NUM>, <FIG>) via use of a threaded screw <NUM> and a nut <NUM>. The threaded screw <NUM> may be received in an aperture (<NUM>, <FIG>) located on the end user PCB (<NUM>, <FIG>). However, in some implementations the use of the screw <NUM> and nut <NUM> may be obviated in favor of other attachment means such as a solder connection made to the solder pins <NUM>, <NUM>. In some variants, an external cover (not shown), adhesive, tape or other attachment mechanism may be utilized to hold the various components of the circular patch antenna <NUM> together.

Referring now to <FIG> and <FIG>, the bottom dielectric patch <NUM> includes a plurality of slots <NUM> that are positioned between each of the feed apertures <NUM>, <NUM>. As illustrated in <FIG> and <FIG>, the circular patch antenna <NUM> includes four (<NUM>) inner feed apertures <NUM> and four (<NUM>) outer feed apertures <NUM> and accordingly includes four (<NUM>) sets of slots <NUM>, although it would be appreciated that the number of sets of slots <NUM> could be greater than four (<NUM>) in some implementations, or less than four (<NUM>) in other implementations. Also, as shown in <FIG> and <FIG>, each set of slots <NUM> consists of six (<NUM>) distinct slots <NUM> that increase in length as the slots <NUM> are positioned further away from the centerline <NUM> of the circular patch antenna <NUM>. The precise number of distinct slots <NUM> in each set of slots <NUM> may be more than (or less than) the number six (<NUM>) in some implementations.

The middle flex PCB(s) <NUM>, <NUM> also includes a set of arc-slots <NUM> that are positioned between the outer perimeter of the respective middle flex PCB <NUM>, <NUM> and the apertures <NUM>, <NUM>. Each arc-slot <NUM> is defined by an arc angle ø and by increasing the arc angle ø, the resonant frequency of the circular patch antenna <NUM> decreases. Conversely, by decreasing the arc angle ø, the resonant frequency of the circular patch antenna <NUM> increases. Accordingly, the circular patch antenna <NUM> may be tuned to a designated frequency without necessarily requiring that the outer diameter of the circular patch antenna <NUM> be increased (or decreased). The sets of arc-slots <NUM> may be symmetrical with respect to the centerline <NUM> of the circular patch antenna <NUM> to minimize phase variations across frequency and space when the circular patch antenna <NUM> is driven for circular polarization. Each of the arc-slots <NUM> may be positioned such that the apertures <NUM>, <NUM> bisect each of the arc-slots <NUM>. As shown in <FIG>, the arc-slots <NUM> are offset from the slots <NUM> located on the bottom dielectric patch <NUM>. In some implementations, the top flex PCB <NUM> may include arc-slots <NUM> in addition to the arc-slots <NUM> that exist in the middle flex PCB(s) <NUM>, <NUM>.

As a brief aside, prior patch antennas typically have been manufactured to include a solid top surface to support a metallization process (typically, a sintered silver paste). However, by removing the requirement that the patch antenna have a solid top surface, as shown for the bottom dielectric patch <NUM>, and using regularly spaced vertical walls without a solid top or bottom surface, a dielectric loading for the bottom dielectric patch <NUM> can be provided that roughly corresponds to the fill ratio of the dielectric to vacuum multiplied by the dielectric constant of the underlying dielectric material. Accordingly, by using these vertical walls, the effective dielectric constant of the bottom dielectric patch <NUM> is higher than it otherwise would be without these vertical walls. Additionally, by removing mass from the bottom dielectric patch <NUM>, the dielectric loading to mass ratio is also improved. The use of these vertical walls also improves upon the manufacturability of these types of patch antennas when using composite (polymer) materials that are formed using an injection molding process. The reason for this is due to the difficulty of injection molding large flat surfaces, as the product will tend to cool unevenly after the injection molding process, resulting in random areas of sink and an uneven surface. However, by incorporating narrow even-thickness walls in the bottom dielectric patch <NUM>, the potential for material sink due to uneven cooling is minimized, thereby improving product yield during the manufacturing process as compared with an injection molded dielectric with large solid flat surfaces.

Referring now to <FIG>, the underside of the top dielectric patch <NUM> is best illustrated. The top dielectric patch <NUM> may include an inner ring <NUM> that is positioned symmetrically about the inner feed apertures <NUM>. The top dielectric patch <NUM> may also include an intermediate ring <NUM> that is positioned between the inner feed apertures <NUM> and the outer feed apertures <NUM>. The top dielectric patch <NUM> may also include one or more outer rings <NUM> that are positioned outside of the outer feed apertures <NUM>. As illustrated in <FIG>, the number of outer rings <NUM> is one (<NUM>), although the number of these outer rings <NUM> may be greater than one (<NUM>) in some implementations. In some implementations, the top dielectric patch <NUM> may include a geometry that is similar to the bottom dielectric patch <NUM> that includes the plurality of sets of slots <NUM>. In another implementation, the bottom dielectric patch <NUM> may include the geometric features of the top dielectric patch <NUM> as shown in <FIG>. The two dielectric patches <NUM>, <NUM> may be configured to operate in different frequency bands and accordingly, the precise geometries chosen may be varied dependent upon differing design constraints as would be readily understood by one of ordinary skill given the contents of the present disclosure.

As shown in <FIG> and <FIG>, the top dielectric patch <NUM> includes alignment features <NUM> and the bottom dielectric patch <NUM> includes alignment features <NUM> that facilitate the alignment of the top dielectric patch <NUM> with respect to the bottom dielectric patch <NUM>. As illustrated in <FIG>, the top dielectric patch <NUM> alignment features <NUM> are protrusions while the bottom dielectric patch <NUM> alignment features <NUM> are cavities that are sized to fit these protrusions. However, it would be recognized by one of ordinary skill given the contents of the present disclosure that these protrusions/cavities may be reversed in some implementations or may be utilized in combinations in which both the top dielectric patch <NUM> and bottom dielectric patch <NUM> each utilizes a combination of protrusions and cavities for each of the top dielectric patch <NUM> and the bottom dielectric patch <NUM>.

Referring now to <FIG>, exemplary dimensional attributes for the circular patch antenna <NUM> are shown and described in detail. For example, the top dielectric patch <NUM> may have a diameter D3 and the bottom dielectric patch <NUM> may have a diameter D4. In some implementations, dimension D3 may differ slightly from dimension D4 although it would be appreciated that some variants may have a dimension D3 that is equivalent to dimension D4. In one implementation, dimension D3 has a diameter of <NUM>, while dimension D3 has a diameter of <NUM>. As shown in <FIG>, the circular patch antenna <NUM> may include a plurality of standoffs <NUM> which assist with the attachment of the circular patch antenna <NUM> to an external PCB. The circular patch antenna <NUM> may also include a height dimension H1 that may be <NUM> in some implementations. The circular patch antenna <NUM> may also include a second height dimension H2 that may be <NUM> in some implementations.

In some variations, the circular patch antenna <NUM> may include three (<NUM>) or more dielectric patches with an accompanying flex PCB for the circular patch antenna <NUM> to operate over a wider range of different frequency ranges. In another embodiment not encompassed by the wording of the claims, a single dielectric patch may be incorporated with an accompanying flex PCB to achieve a specific operating frequency. Such an implementation may be desirable when overall height constraints dictate a lower profile circular patch antenna <NUM> design. These and other variations would be readily apparent to one of ordinary skill given the contents of the present disclosure.

Claim 1:
A circular patch antenna (<NUM>), comprising:
a first dielectric patch (<NUM>) comprising a first plurality of inner and outer feed apertures (<NUM>, <NUM>);
a top metallization (<NUM>) positioned on top of the first dielectric patch (<NUM>);
a second dielectric patch (<NUM>) comprising a second plurality of inner and outer feed apertures (<NUM>, <NUM>);
the first dielectric patch (<NUM>) is positioned over the second dielectric patch (<NUM>);
wherein the first plurality of inner and outer feed apertures (<NUM>, <NUM>) and the second plurality of inner and outer feed apertures (<NUM>, <NUM>) are aligned with one another;
a middle metallization (<NUM>) that is positioned between the first dielectric patch (<NUM>) and the second dielectric patch (<NUM>), the middle metallization (<NUM>) comprising a plurality of arc slots (<NUM>), each of the plurality of arc slots (<NUM>) being positioned between the first and second plurality of inner and outer feed apertures (<NUM>, <NUM>) and an external periphery of the middle metallization (<NUM>); and
a bottom metallization (<NUM>) that is disposed below the second dielectric patch (<NUM>), the bottom metallization (<NUM>) comprising a ground plane for the circular patch antenna (<NUM>).