ANTENNA STRUCTURE

In some aspects, the techniques described herein relate to an apparatus including: a ground plane element including: a non-conductive support layer, a conductive layer arranged on the non-conductive support layer, and at least one orifice through the non-conductive support layer and the conductive laminate layer; one or more radiating elements including a feed line and a solder pad, wherein each of the one or more radiating elements is secured to and electrically connected to the ground plane element via soldering of the solder pad to the conductive laminate layer; and at least one connector arranged in the at least one orifice and electrically connected to the feed line.

TECHNICAL FIELD

The present disclosure relates to techniques for constructing antennas, including Vivaldi antennas.

BACKGROUND

A Vivaldi antenna (sometimes referred to as a tapered slot antenna) is traditionally a co-planar broadband-antenna. Vivaldi antennas may be constructed by forming an open space in a solid piece of sheet metal, a printed circuit board, or from a dielectric plate metalized on one or both sides. From the open space area the energy reaches an exponentially tapered pattern via a symmetrical slot line. In an antipodal Vivaldi antenna, a first Vivaldi arm is formed on a first side of a dielectric plate material, and a second Vivaldi arm is formed on a second side of the dielectric plate material. The open space is formed in areas of the dielectric plate material not covered by either radiating element. Vivaldi antennas may be made for linear polarized waves through the use of a single open space radiator. Using two radiators perpendicularly arranged allows for Vivaldi antennas that receive both horizontally and vertically polarized signals. If the arrangement is also concentric, the two radiating elements may be fed with90-degree phase-shifted signals to provide circular polarized electromagnetic waves.

Vivaldi antennas may be configured for almost any frequency range, as the Vivaldi structure is scalable in size. Printed circuit technology makes this type of antenna cost effective at microwave frequencies exceeding1GHz. Advantages of Vivaldi antennas may include their broadband characteristics, their ease of manufacturing, and their ease of impedance matching using microstrip line modeling methods. However, dual-polarized Vivaldi antennas generally include heavy mechanical support structures.

DETAILED DESCRIPTION

Overview

In some aspects, the techniques described herein relate to an apparatus including: a ground plane element including: a non-conductive support layer, a conductive layer arranged on the non-conductive support layer, and at least one orifice through the non-conductive support layer and the conductive layer; one or more radiating elements including a feed line and a solder pad, wherein each of the one or more radiating elements is secured to and electrically connected to the ground plane element via soldering of the solder pad to the conductive layer; and at least one connector arranged in the at least one orifice and electrically connected to the feed line.

In some aspects, the techniques described herein relate to an apparatus including: a ground plane element including: a non-conductive support layer, a conductive layer arranged on the non-conductive support layer, and a plurality of orifices through the non-conductive support layer, and the conductive layer; a plurality of antenna elements arranged on the ground plane element, wherein each of the plurality of antenna elements includes a feed line and a solder pad, and wherein each of the plurality of antenna elements is secured to and electrically connected to the ground plane element via soldering of its respective solder pad to the conductive layer; and a plurality of connectors, wherein each of the plurality of connectors is arranged in a respective one of the plurality of orifices and electrically connected to a respective one of the feed lines.

Example Embodiments

In accordance with discussion above, provided for herein are techniques for providing wideband, lightweight, and low cost antenna elements. The antenna elements constructed according to the disclosed techniques may provide wideband radio frequency (RF) performance and polarization diverse capabilities from a single, light-weight antenna.

With reference made toFIGS.1-5, depicted therein is an antipodal Vivaldi antenna (AVA)100configured according to the techniques disclosed herein. AVA100includes a horizontal element105, a vertical element117and a ground plane element130. As an antipodal Vivaldi antenna, horizontal element105includes a first side107and a second side109, illustrated in more detail inFIG.4. As shown inFIG.4, a first Vivaldi arm110is arranged on first side107and a second Vivaldi arm111is arranged on the second side109. The first Vivaldi arm110and the second Vivaldi arm111are formed as microstrip structures on the copper clad laminate substrate of horizontal element105. The microstrip structure of first Vivaldi arm110includes feed line connection pad113which connects feed line112to antenna feed pin141(illustrated inFIG.1). Second Vivaldi arm111is formed as a microstrip structure on second side109of horizontal element105. Included in second Vivaldi arm111is solder pad106. As will be described in greater detail below, solder pad106will be used to solder horizontal element105to ground plane element130. Horizontal element105also includes solder pads114aand114bfor attaching sub miniature push-on micro (SMPM) connector140. Horizontal element105also includes notch116which engages with channel126of vertical element117(illustrated inFIG.5).

Turning to vertical element117(illustrated in detail inFIG.5), vertical element117includes a similar microstrip structure as that of horizontal element105. Vertical element117includes a first side118and a second side119. As shown inFIG.5, a first vertical Vivaldi arm120is arranged on first side118and a second vertical Vivaldi arm122is arranged on the second side119. The first vertical Vivaldi arm120and the second vertical Vivaldi arm122are formed as microstrip structures on the copper clad laminate substrate of vertical element117. The microstrip structure of first vertical Vivaldi arm120includes feed line connection pad124which connects feed line123to antenna feed pin143(illustrated inFIG.1). Second vertical Vivaldi arm122is formed as a microstrip structure on second side119of vertical element117. Included in second vertical Vivaldi arm122is solder pad125. As will be described in greater detail below, solder pad125will be used to solder vertical element117to ground plane element130. Vertical element117includes solder pads126aand126bfor attaching SMPM connector142. As noted above, vertical element117also includes channel126which engages with notch116of horizontal element105(illustrated inFIG.4).

Horizontal element105and vertical element117are arranged on ground plane element130, as illustrated inFIGS.1-3. According to the techniques disclosed herein, ground plane element130is formed from a combination of a non-conductive support layer131and a conductive layer132. According to the specific example embodiment ofFIGS.1-3, ground plane element130is formed from a laminate of copper (serving as the conductive layer132) and a dielectric or insulating material (serving as the non-conductive support layer131) which are laminated together to form a copper laminate material. According to a specific example, the copper laminate material may be constructed from a printed circuit board (PCB) material, in which the copper foil serves as the conductive layer132and the PCB core serves as the non-conductive support layer. Ground plane element130may include additional materials, such as a PCB prepreg layer.

According to another example, the conductive layer132may be constructed from a spun metal layer, and the non-conductive support layer131may be constructed from a polyimide material. As understood by the skilled artisan, polyimide materials are polymers containing imide groups belonging to the class of high-performance plastics, such as those used in power electronics found in high speed switch devices.

As understood from the example materials described above, conductive layer132may be formed from a thin conductive layer, such as a copper or other metallic foil or a thin spun metal layer. The use of such materials for ground plane element130enables AVA100to have a lightweight design while retaining desirable performance characteristics. Specifically, ground plane element130may provide a lightweight ground plane with strong radio frequency (RF) performance. Typical related art Vivaldi antennas rely on heavy aluminum mechanical structures to achieve similar RF performance. Accordingly, AVA100maintains similar RF performance with significantly lighter weight mechanical structures.

Ground plane element130includes two orifices-orifice133and orifice134. Orifice133allows SMPM connector140to pass through ground plane element130and connects antenna feed pin141to feed line connection pad113. Orifice134allows SMPM connector142to pass through ground plane element130and connects antenna feed pin143to feed line connection pad124.

To secure horizontal element105to ground plane element130, solder pad106is soldered to conductive layer132. Similarly, vertical element117is secured to substrate130by soldering solder pad125to conductive layer132. The use of solder150to connect vertical element117to conductive layer132is illustrated inFIG.6. While obscured inFIG.6by horizontal element105, horizontal element105is similarly secured to ground plane element130via solder between solder pad106and conductive layer132.

Further structural integrity is provided to AVA100by epoxying SMPM connectors140and142to non-conductive support layer131of ground plane element130, as illustrated inFIG.7. As illustrated inFIG.7, epoxy160secures SMPM connectors140and142to non-conductive support layer131. The combination of solder150(illustrated inFIG.6) and epoxy160(illustrated inFIG.7) provide for a structurally sound antenna structure that is simple to construct, easy to integrate into, for example, antenna arrays, and that is easily scalable to operate at the L (1-2 GHZ), S (2-4 GHZ), C (4-8 GHZ), X (8-12 GHz), Ku (12-18 GHz), K (18-27 GHZ) and Ka (27-40 GHz) frequency bands.

Based upon the feeding provided by SMPM connector140and SMPM connector142, AVA100may radiate linear horizontal polarization by feeding only SMPM connector140, radiate linear vertical polarization by feeding only SMPM connector142, and radiate dual-circular polarization by connecting to a 90° hybrid coupler to provide a 90° phase shift between SMPM connector140and SMPM connector142.

As discussed above, the combination of solder150(illustrated inFIG.6) and epoxy160(illustrated inFIG.7) provide for a structurally sound antenna structure. However, if additional structural integrity is required or beneficial to a particular application, additional support structures may be included in AVA100, as illustrated inFIGS.8and9. As shown inFIGS.8and9, support structures180a-dmay be included in AVA100. Support structures180aand180cmay be provided with a “U” shape cross-section to engage with the ends of horizontal element105. Similarly, support structures180band180dare configured to engage with the ends of vertical element117. As illustrated inFIG.9, ground plane element130includes orifices182a-dformed in non-conductive support layer131and conductive layer132to engage and secure support structures180a-d. Orifices180a-dmay be sized such that they secure support structures180a-dvia a friction fit. According to other example embodiments support structures180a-dmay be secured in orifices182a-dvia gluing, epoxying, sonic welding, or techniques known to the skilled artisan.

FIGS.8and9also differ from the embodiment ofFIGS.1-5in that the orientation of non-conductive support layer131and conductive layer132is reversed. Specifically, non-conductive support layer131is on the same side of the ground plane element130as horizontal element105and the vertical element117. Accordingly, the embodiment ofFIGS.8and9illustrates an alternative method of mounting horizontal element105and the vertical element117to ground plane element130. According to this embodiment, solder pad125would be soldered to the portion of connector142exposed by orifice134. Connector142would then be soldered to conductive layer132on the opposite side of ground plane element130electrically and mechanically connecting vertical element117to ground plane element130. Connector140would be analogously soldered to horizontal element105and conductive layer132to electrically and mechanically connect horizontal element105to ground plane element130. This reversed ground plane element130may be applied to the structure illustrated inFIGS.1-7(i.e., the embodiment without support structures180a-dand orifices182a-d) without deviating the antenna construction techniques disclosed herein.

In addition to the structural benefits discussed above, antennas constructed according to the disclosed techniques also exhibit beneficial electrical properties. For example, illustrated inFIG.10is a comparison of the realized gain of an AVA constructed according to the disclosed techniques compared to the simulated values. Specifically,FIG.10compares the simulated and measured realized gain for both horizontal and vertical polarized operation of the antenna element.FIG.11provides a graph comparing the measured versus simulated vertical-to-horizontal port coupling of the AVA.FIG.12provides a graph comparing the measured versus simulated voltage standing wave ratio for both horizontal and vertical polarized operation of the AVA. As illustrated in these graphs, the AVA element not only exhibits strong electrical performance, but its measured performance substantially matches its simulated performance. This agreement between the measure and simulated performance evidences the success of the disclosed techniques. Because the measured performance substantially matches the simulated performance, the techniques may be confidently applied when designing new antenna structures knowing the resulting physical antenna will behave as expected.

The disclosed techniques also provide for radiation patterns that are not only applicable to many different applications, but that also match their simulated performance. Illustrated inFIGS.13a-fare comparisons of the measured horizontal radiation pattern for an AVA constructed according to the disclosed techniques compared with the simulated pattern for the same structure, across an operating frequency range of the antenna. Not only are the radiation patterns fairly hemispherical, but the measured patterns substantially match the simulation patterns.FIGS.14a-fillustrate comparisons of the measured vertical radiation pattern for an AVA constructed according to the disclosed techniques compared with the simulated pattern for the same structure across the operating frequency range of the antenna. As with the horizontal radiation patterns ofFIGS.13a-f, the vertical radiation patterns ofFIGS.14a-fare fairly hemispherical and substantially match the simulation patterns.

In summary, provided for herein are techniques for providing an antenna and antenna structure that has a simple and light-weight construction. The disclosed techniques also provide for antennas that exhibit desirable gain, radiation patterns, and S-parameters in a small package. Furthermore, testing of antennas constructed according to the disclosed techniques exhibit performance that closely measures their simulated performance, indicating a successful and repeatable antenna design. Given the lightweight and high gain performance achievable through the disclosed techniques, the techniques may be particularly applicable to airborne applications, including satellite low earth orbit applications. When the disclosed techniques are leveraged to implement AVA elements, the techniques may be particularly applicable to airborne telemetry applications.

The techniques of this disclosure are not limited to antenna elements. Instead, as illustrated inFIG.15, the disclosed techniques may be applied to antenna arrays. Specifically, illustrated inFIG.15are a number of AVA antenna elements500a-gthat have been arranged into antenna array505. While only seven AVA antenna elements500a-gare visible, antenna array505is 4×4 array that includes 16 AVA antenna elements. Each of antenna elements500a-gis constructed substantially the same as AVA100ofFIGS.1-7. However, antenna array505includes a single ground plane element530. Like ground plane element130, ground plane element530is constructed from non-conductive support layer531and a conductive layer532. Accordingly, ground plane element530may be formed from a laminate of copper (serving as the conductive layer532) and a non-conductive material (serving as the non-conductive support layer531) which are laminated together to form a copper laminate material. Non-conductive support layer531provides a light substrate that supports AVA antenna elements500a-g, while conductive layer532exhibits the necessary electrical properties so that ground plane element530serves as an effective ground plane for antenna array505. Antenna array505may also include a cover540which serves to protect and add structural rigidity to antenna array505. Cover540is configured to be essentially transparent to the radiation frequencies that are sent or received by antenna elements500a-gso as to not negatively affect the performance of antenna array505. For example, cover540may be constructed from a closed cell foam. A closed cell foam layer may also be added to ground plane element130provide additional structural support and/or rigidity to antenna array505.

The above description of AVA100and antenna array505has been provided with regard to an example embodiment in which the radiating elements are embodied as Vivaldi elements, and in particular AVA elements. However, the techniques described herein may be applied to other types of antenna elements, including vertical tightly coupled dipole antenna elements and arrays, Planar Ultrawideband Modular Antenna (PUMA) element and arrays, and Stacked Patch elements and arrays. As understood by the skilled artisan from the present disclosure, the disclosed techniques may be implementing in conjunction with any number of different antenna elements to significantly reduce the weight, design complexity, cost, and schedule for designing and constructing antenna elements and arrays.

In summary, the techniques described herein relate to an apparatus including: a ground plane element including: a non-conductive support layer, a conductive layer arranged on the non-conductive support layer, and at least one orifice through the non-conductive support layer and the conductive layer; one or more radiating elements including a feed line and a solder pad, wherein each of the one or more radiating elements is secured to and electrically connected to the ground plane element via soldering of the solder pad to the conductive layer; and at least one connector arranged in the at least one orifice and electrically connected to the feed line.

In some aspects, the techniques described herein relate to an apparatus, wherein the one or more radiating elements includes a Vivaldi radiating element.

In some aspects, the techniques described herein relate to an apparatus, wherein the Vivaldi radiating element includes an antipodal Vivaldi radiating element.

In some aspects, the techniques described herein relate to an apparatus, wherein the one or more radiating elements include a first Vivaldi radiating element and a second Vivaldi radiating element arranged orthogonally and concentrically to each other.

In some aspects, the techniques described herein relate to an apparatus, wherein the first Vivaldi radiating element is configured to transmit or receive radiation with a first linear polarization; and wherein the second Vivaldi radiating element is configured to transmit or receive radiation with a second linear polarization orthogonal to the first linear polarization.

In some aspects, the techniques described herein relate to an apparatus, wherein the first Vivaldi radiating element and the second Vivaldi radiating element are configured to transmit or receive radiation with circular polarization.

In some aspects, the techniques described herein relate to an apparatus, wherein the conductive layer includes a copper conductive laminate layer.

In some aspects, the techniques described herein relate to an apparatus, wherein the non-

conductive support layer and the conductive layer include a copper clad laminate material.

In some aspects, the techniques described herein relate to an apparatus, wherein the at least one connector is epoxied to the ground plane element.

In some aspects, the techniques described herein relate to an apparatus, further including a support structure secured within a second orifice in the ground plane element and supporting an edge of the one or more radiating elements.

In some aspects, the techniques described herein relate to an apparatus, wherein the one or more radiating elements includes a microstrip structure on a copper clad laminate substrate.

In some aspects, the techniques described herein relate to an apparatus, wherein the solder pad includes a microstrip structure on a copper clad laminate substrate.

In some aspects, the techniques described herein relate to an apparatus including: a ground plane element including: a non-conductive support layer, a conductive layer arranged on the non-conductive support layer, and a plurality of orifices through the non-conductive support layer, and the conductive layer; a plurality of antenna elements arranged on the ground plane element, wherein each of the plurality of antenna elements includes a feed line and a solder pad, and wherein each of the plurality of antenna elements is secured to and electrically connected to the ground plane element via soldering of its respective solder pad to the conductive layer; and a plurality of connectors, wherein each of the plurality of connectors is arranged in a respective one of the plurality of orifices and electrically connected to a respective one of the feed lines.

In some aspects, the techniques described herein relate to an apparatus, wherein each of the plurality of antenna elements includes a Vivaldi antenna element.

In some aspects, the techniques described herein relate to an apparatus, wherein each of the plurality of antenna elements includes an antipodal Vivaldi antenna element.

In some aspects, the techniques described herein relate to an apparatus, wherein the conductive layer includes a copper laminate layer.

In some aspects, the techniques described herein relate to an apparatus, wherein each of the plurality of connectors is epoxied to the non-conductive support layer.

In some aspects, the techniques described herein relate to an apparatus, further including a cover arranged on the plurality antenna elements opposite to the ground plane element.

In some aspects, the techniques described herein relate to an apparatus, wherein the cover is transparent to radiation sent or received by the plurality of antenna elements.

In some aspects, the techniques described herein relate to an apparatus, wherein the cover includes a closed cell foam.