阅读说明：本技术 螺旋天线及相关制造技术 (Helical antenna and related manufacturing techniques ) 是由 P·J·亚当斯 T·V·席基纳 J·P·黑文 J·E·贝内迪克特 于 2018-11-06 设计创作，主要内容包括：本文描述的构思、系统、电路和技术针对可以使用增材制造技术提供的螺旋天线,从而提供一种能够在比使用标准光刻或印刷电路板(PCB)制造工艺制造的螺旋天线更高的频率下工作的天线。(The concepts, systems, circuits, and techniques described herein are directed to a helical antenna that may be provided using additive manufacturing techniques, thereby providing an antenna that is capable of operating at higher frequencies than helical antennas manufactured using standard photolithographic or Printed Circuit Board (PCB) manufacturing processes.)

1. A helical antenna, comprising:

an antenna substrate having a first surface and a second surface;

two or more spiral conductors disposed on a first surface of the antenna substrate, each of the spiral antennas having a first end defining an inner radius of the spiral and a second end defining an outer radius of the spiral;

a feeding circuit substrate disposed over the second surface of the antenna substrate;

a feeding circuit provided in or on the feeding circuit substrate;

a vertical transmit feed line having a first end coupled to the first end of each spiral conductor and a second end coupled to the feed circuit; and

a vertical transmit feed line Faraday wall surrounding the vertical transmit feed line.

2. The helical antenna of claim 1, wherein said feed circuit substrate comprises a first ground plane and a second ground plane.

3. The helical antenna of claim 2, wherein said vertical transmit feed line faraday wall has a cylindrical shape disposed between said first ground plane of said feed circuit substrate and said first surface of said antenna substrate.

4. The helical antenna of claim 3, wherein said feed circuit comprises two feed lines, a first end of a first helical conductor of said two or more helical conductors coupled to a first feed line, and a first end of a second helical conductor of said two or more helical conductors coupled to a second feed line.

5. The helical antenna of claim 4, wherein said feed circuit Faraday wall surrounds said two feed lines.

6. A helical antenna according to claim 3, further comprising a feed circuit faraday wall disposed between said first and second ground planes of the feed circuit substrate and surrounding said feed circuit.

7. The helical antenna of claim 2, further comprising a feed circuit faraday wall disposed between said first and second ground planes of said feed circuit substrate and surrounding said feed circuit.

8. A helical antenna, comprising:

an antenna substrate having a first surface and a second surface;

two or more spiral conductors disposed on a first surface of the antenna substrate, each of the spiral antennas having a first end defining an inner radius of the spiral and a second end defining an outer radius of the spiral;

a feed circuit substrate disposed over the second surface of the antenna substrate, the feed circuit substrate having a first ground plane and a second ground plane;

a feeding circuit provided in or on the feeding circuit substrate; and

a feed circuit Faraday wall disposed between the first and second ground planes of the feed circuit substrate and surrounding the feed circuit.

9. The helical antenna of claim 8, further comprising a vertical transmit feed line having a first end coupled to the first end of each helical conductor and a second end coupled to said feed circuit.

10. The helical antenna of claim 9, further comprising a vertical transmit feed line faraday wall surrounding said vertical transmit feed line.

11. The helical antenna of claim 10, wherein said vertical transmit feed line faraday wall has a cylindrical shape disposed between said first ground plane of said feed circuit substrate and said first surface of said antenna substrate.

12. The helical antenna of claim 11, wherein said feed circuit comprises two feed lines, a first end of a first helical conductor of said two or more helical conductors coupled to a first feed line, and a first end of a second helical conductor of said two or more helical conductors coupled to a second feed line.

13. The helical antenna of claim 12, wherein said feed circuit faraday wall surrounds said two feed lines.

14. An AMT processing method for manufacturing a helical antenna, comprising:

(a) removing conductive material from an antenna substrate to form two or more conductive spirals on the substrate;

(b) forming an opening in the substrate extending from a first surface of the substrate to a second opposing surface at the first end of each spiral conductor;

(c) forming an opening around each of said openings terminating at a first end of said spiral, said opening having a cylindrical shape; and

(d) each opening is filled with conductive ink to form a conductive signal path and a conductive wall in the antenna substrate.

15. The method of claim 14, wherein removing conductive material, forming openings in the substrate, and/or forming an opening around each of the openings comprises a milling technique.

16. The method of claim 14, further comprising forming a conductive vertical radiator coupled to the helical antenna and the signal path.

17. A method of forming a conductive vertical radiator coupled to a helical antenna and a feed circuit, comprising:

pre-tinning the bottom trace of the feed circuit with solder bumps after the signal trace has been milled out of the double-clad dielectric substrate;

drilling holes in the top layer of the feed circuit and bonding film to allow room for the solder mass to reflow in the cavity during bonding;

pre-cutting a cavity leading to the top layer with the spiral and laminating the assembly together;

inserting or filling copper into the hole until the copper contacts the solder mass; and

the top of the copper is pressed with a soldering iron to reflow the solder at the feed circuit.

Background

As known in the art, a so-called helical antenna is a Radio Frequency (RF) antenna provided by a substrate having two or more conductors arranged in a helical shape above it. It is also known that the upper limit of the operating frequency of a helical antenna is defined by the inner radius (r) of the antenna_i) By definition, the smaller the inner radius of the antenna, the higher the operating frequency. However, limitations of conventional manufacturing techniques (e.g., standard photolithographic or Printed Circuit Board (PCB) manufacturing processes) limit the inner radius size of the spiral antenna that can be implemented, thereby limiting the upper operating frequency of the spiral antenna.

Disclosure of Invention

In accordance with the concepts, systems, circuits, and techniques described herein, a helical antenna includes an antenna substrate having two or more helical conductors disposed on a first surface thereof, each of the helical antennas having a first (or inner) end defining an inner radius of the helix and a second (or outer) end defining an outer radius of the helix. The second surface of the antenna substrate is disposed above the first ground plane surface of the feeding circuit substrate. The first end of each spiral conductor has a vertical transmission feed line coupled thereto. Each vertical transmission feed line is coupled to a feed circuit disposed in or on the feed circuit substrate. A faraday wall having a cylindrical shape is disposed between the first ground plane of the feed circuit substrate and the first surface of the antenna substrate and surrounds the vertical transmission feed line. The feed circuit faraday wall is disposed between the ground planes around the feed circuit and surrounds the feed circuit.

With this particular arrangement, a helical antenna and a feed circuit are provided. Faraday walls disposed around the antenna feed circuit and the vertical transmission feed line increase the degree of isolation between signals propagating in different parts of the circuit.

According to another aspect of the concepts described herein, an Additive Manufacturing Technique (AMT) of manufacturing a helical antenna includes removing (e.g., by a milling technique) conductive material from an antenna substrate to form two or more conductive spirals on the substrate; forming (e.g., by a milling technique) an opening in the substrate extending from a first surface to a second, opposite surface of the substrate at the first end of each spiral conductor; forming (e.g., by a milling technique) an opening around each of the openings terminating at the first end of the spiral, the openings having a cylindrical shape; and filling each opening with conductive ink to form a conductive signal path and a conductive wall in the antenna substrate.

With this particular technology, the AMT manufacturing method provides an antenna that has a low manufacturing cost in production, can be quickly prototyped (prototype), and customized to meet design requirements. AMT is used to miniaturize component sizes to operate at frequencies in the range of about 25GHz and higher, which is higher than the operating frequencies heretofore available for helical antennas.

Thus, the use of AMT to manufacture helical antennas overcomes current manufacturing limitations due to the use of standard photolithography or printed circuit board manufacturing Processes (PCBs).

The antenna described herein solves the problems associated with conventional PCB fabrication by utilizing design features (e.g., vertical transmit feed circuitry, faraday walls, etc.) that utilize at least the milling and printing capabilities provided by AMT. This milling and printing capability of the AMT machine allows for the fabrication of the required feature sizes for antennas operating at frequencies in the range of about 25GHz to about 25 GHz. In an embodiment, using the designs and techniques described herein, a size of about 0.002 "may be achieved for a trace width and a size of about 0.005" may be achieved for a diameter of a vertical transmission feed circuit.

Furthermore, the printed conductive faraday walls serve to confine the electric field and can be machined in the same manufacturing step as milling other features. This saves considerable labor costs, thereby reducing the overall cost of the assembly. Finally, a custom printed connector interface is used so that the device can be tested using standard coaxial connectors.

The antenna design described herein uses AMT technology such as faraday walls, vertical transmission connections, single step milling and filling operations, small (2x2 elements) components, and milled copper traces. It represents an antenna structure that is completely manufactured with AMT and that can reliably produce components in a cost-effective and efficient manner. Furthermore, antenna designs using AMTs greatly reduce production costs, can be quickly prototyped and customized to meet design requirements. The helical antenna design described herein uses AMT to miniaturize the component size to operate at a frequency higher than the operating frequency of prior art helical antennas.

Drawings

Various aspects of at least one embodiment are discussed below with reference to the accompanying drawings, which are not intended to be drawn to scale. The accompanying drawings are included to provide an illustration and a further understanding of the various aspects and embodiments of the present application and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of the application. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. The foregoing features will be more fully understood from the following description of the drawings, in which:

FIG. 1 is an isometric view of a helical antenna;

FIG. 1A is a bottom view of a connector interface to a stripline feed circuit;

FIG. 1B is an isometric view of the connector interface to the stripline feed circuit;

FIG. 1C is a side view of the connector interface to the stripline feed circuit;

fig. 2 is a flow diagram of a process for manufacturing a helical antenna using Additive Manufacturing Technology (AMT), which may be the same as or similar to the antenna of fig. 1;

FIG. 3 is a flow chart of a process of manufacturing a feed circuit, which may be the same as or similar to the feed circuit of FIG. 1 using an AMT; and

fig. 4-4D are a series of diagrams illustrating a process of coupling a helical antenna to a feed circuit.

Detailed Description

The concepts, systems, circuits, and techniques described herein are directed to a spiral antenna that may be provided using additive manufacturing techniques in order to provide a spiral antenna that is capable of operating at higher frequencies than spiral antennas manufactured using standard photolithography or printed circuit board manufacturing Processes (PCBs).

It is to be understood that the embodiments of the methods and apparatus discussed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. These methods and apparatus can be implemented in other embodiments and can be practiced or carried out in various ways. The examples of specific embodiments provided herein are for illustrative purposes only and are not intended to be limiting. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," "involving," and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to "or" may be interpreted as being inclusive, and thus any term described using "or" may mean any single, more than one, or all of the described terms. Any reference to front and back, left and right sides, top and bottom, upper and lower, ends, sides, vertical and horizontal, etc., is for convenience of description and does not limit the present systems and methods or their components to any one positional or spatial orientation.

Referring now to fig. 1, the helical antenna assembly 8 includes a helical antenna portion 10 coupled to a feed circuit portion 20. The spiral antenna portion 10 includes an antenna substrate 12 having a first surface 12a and a second opposing surface 12b, with two or more spiral conductors 14a, 14b (generally designated 14) disposed or otherwise formed on the first surface 12a of the antenna substrate 12. Although only two spiral conductors 14 are shown in the illustrative embodiment of fig. 1, one of ordinary skill in the art will appreciate that any number N of spiral conductors 14 may be used. The specific number of spiral conductors 14 used in any particular application depends on a number of factors including, but not limited to, radiation distance, transmit power, platform size.

One of ordinary skill in the art will understand how to select the number of spiral conductors for a given application. Further, one of ordinary skill in the art will also understand how to select a particular spiral shape (e.g., an archimedean spiral, a square spiral, a star spiral, etc.) for a particular application.

Each spiral conductor has a first (or inner) end 15a defining the inner radius of the spiral and a second (or outer) end 15b defining the outer radius of the spiral. Characteristics of the spiral conductor that affect the radiation pattern of the spiral antenna include, but are not limited to, the spacing between turns, the width of each spiral conductor (or arm), and the inner radius r_iAnd an outer radius r_o. It will be appreciated that the spacing s and width w may vary at different points along the spiral, depending on the particular type of spiral antenna. That is, in an embodiment, the spiral conductor 14 may not maintain the same width over the entire length of the spiral (where the length of the spiral refers to the length of the spiral conductor 14 measured along the centerline of the spiral conductor 14). Similarly, in embodiments, the spacing between the spiral conductors 14 along the entire length of the spiral may not be constant.

Measuring the inner radius r of the spiral from the center of the spiral to the center of the first turn_iAnd the outer radius of the spiral is measured from the center of the spiral to the center of the outermost turn. In addition to these design parameters, the lowest operating frequency f of the helical antenna_low＝c/2πr_oMaximum operating frequency of f_high＝c/2πr_i. Here corresponding to the speed of light. In the (r, θ) coordinate system, the spiral grows along both the r-axis and the θ -axis.

The antenna substrate 12 is disposed on the first ground plane surface 20a of the stripline feed circuit 20 and is coupled to the first ground plane surface 20 a. In an embodiment, the antenna may be coupled to the stripline feed circuit 20 using a vertical transition to create a two-wire feed 22. One particular technique for connecting the helical stripline feed circuits 20 will be described below in conjunction with fig. 4 through 4D. The stripline feed circuit 20 includes a second ground plane surface 20 b. Here, the strip line feeding circuit 20 is provided by a pair of substrates 23, 24, and a feeding circuit 26 is provided between the pair of substrates 23, 24.

The first end of each spiral conductor has a vertical launch (vertical launch) feed 22 coupled thereto. Each vertical transmission feed line 22 is coupled to a feed circuit 26 provided as part of the stripline feed circuit 20. In this illustrative embodiment, the feed circuit is implemented as a stripline circuit including two dielectric substrates 23, 24 and having an upper ground plane 20a and a lower ground plane 20 b. In other embodiments, the feed circuit may be implemented using other techniques (e.g., as a microstrip feed circuit, as a suspended air stripline circuit, or using other techniques). That is, it is recognized that the feed may be implemented in forms other than stripline circuits.

A faraday wall 30 having a cylindrical shape is disposed between the first ground plane 20a of the stripline feed circuit substrate and the first surface 12a of the antenna substrate, and surrounds (i.e., encircles) the vertical transmission feed 22. In a preferred embodiment, the faraday wall 30 is provided having a solid cylindrical shape. In embodiments, a cylindrical wall may be provided having a gap, slit, or other form of opening therein. In an embodiment, one end of the faraday wall 30 is in electrical contact with the feed circuit ground plane 20a, and a second, opposite end of the faraday wall extends through the antenna substrate 12, but not to the antenna substrate surface 12 a. In an embodiment, the faraday wall 30 may or may not be in physical contact with the second ground plane 20 b. Such conductive faraday walls 30 confine the electric field and thus provide isolation and mode suppression. Thus, the faraday wall 30 acts as a vertical transmission isolation and mode suppression structure, thereby helping to provide the antenna with desired antenna operating characteristics.

The feed circuit faraday wall 32 is disposed between the ground planes 20a, 20b of the stripline feed circuit 20 and surrounds or encompasses the feed circuit 26. In an embodiment, the faraday wall 32 is in electrical contact with both the upper ground plane and the power supply ground plane of the stripline circuit. In an embodiment, the faraday wall is in physical contact with both the upper ground plane and the power supply ground plane of the stripline circuit. Similar to the faraday wall 30, the faraday wall 32 confines the electric field from the feed circuit 26. In embodiments, a wall 32 may be provided having a gap, slit, or other form of opening therein.

The radio frequency connector 33 is coupled to an input/output port 34 of the feeding circuit 26. In an embodiment, the input/output port 34 is provided as a custom printed connector interface 34 that allows the radio frequency connector 33 to be provided as a standard coaxial connector. As shown in fig. 1A-1C, where like elements of fig. 1 are provided with like reference numerals, the interface 34 uses an AMT prepared vertical launcher 35 to allow the adapter to interface with a stripline feed.

It will be appreciated that different spiral antenna designs may be obtained by varying the number of turns they contain, the spacing between their turns, and the width of their arms. It should also be understood that the antenna substrate is selected to have a particular dielectric constant and dimensions to provide an antenna having desired radiation pattern characteristics. In one embodiment, to operate in the frequency range of about 25GHz to about 35GHz, the antenna substrate 12 may be provided with a thickness in the range of about 70-80 mils (mil) and a relative dielectric constant (permeability) of about 2.2, the spiral conductor 14 may be provided with a width in the range of about 2-3 mils, an inner radius of about 0.055 ", and an outer radius of about 0.185", and the feed substrate may be provided with a thickness of about 20 mils.

Of course, one of ordinary skill in the art will appreciate that a compromise may be made between substrate thickness and relative permittivity values to achieve approximately the same antenna electrical characteristics (e.g., a relatively thin substrate having a relatively high permittivity value may be used to achieve substantially the same antenna operating characteristics as a relatively thick substrate having a lower relative permittivity).

In an embodiment, the antenna described herein includes two conductive spirals (or "arms") extending outward from a center and a faraday wall having a cylindrical shape and disposed about an antenna feed coupled to the arms. The antenna may be a flat disc with a spiral conductor disposed on its surface, or the spiral conductor may extend in a three-dimensional shape, e.g., as if disposed on a truncated conical structure. The direction of rotation of the helix defines the direction of antenna polarization. Additional spirals can also be included to form a multi-spiral structure. In an embodiment, the helix is abluminal; that is, there is a cavity of air or non-conductive material or vacuum surrounded by conductive walls. The cavity changes the antenna pattern into a unidirectional shape.

In an embodiment, the two substrates may be fabricated separately and then bonded together. Then a vertical transition will be placed.

Referring now to fig. 2, an illustrative Additive Manufacturing Technology (AMT)40 is used to fabricate a helical antenna, which may be the same as or similar to the antenna 10 described above in connection with fig. 1, with the process beginning with the removal (e.g., by a milling technique) of conductive material from the first surface of the antenna substrate to form two or more conductive spirals on the first surface of the substrate, as indicated at process block 42. Thus, small feature sizes are achieved by milling away the copper leaving the spiral conductor.

As indicated at process block 44, at a first end of each spiral conductor, an opening may be formed in the antenna substrate extending from a first surface of the antenna substrate to a second, opposite surface using a milling (or other) technique. Such an opening would then be used to form a vertical transmit feed line (e.g., vertical transmit feed line 22 shown in fig. 1).

As indicated at process block 46, milling techniques may be used to form an opening around each vertical transmission feed line opening. In an embodiment, the opening surrounding each vertical transmission feed line opening is arranged to have a continuous cylindrical shape and to surround the vertical transmission feed line opening. In an embodiment, the cylindrical opening extends from the second surface of the antenna substrate to a position that is 50% to 95% through the antenna substrate (i.e. the cylinder extends only partially through the antenna substrate).

After the vertical transmission feed line openings and the cylindrical openings are formed in the antenna substrate, processing proceeds to process block 48 where processing is performed to fill each opening with conductive ink to form conductive signal paths and conductive walls in the antenna substrate.

In an embodiment, a series of cylindrical openings each having a different diameter may be formed in process block 46 such that after filling with conductive ink, the segmented cylindrical walls are disposed around the vertical launch feedlines. It will be appreciated that the wall is more likely to be a cylindrical ring with two cylindrical openings at the vertical transition located inside.

Referring now to fig. 3, an illustrative AMT method 58 of manufacturing a feed circuit may be the same as or similar to the feed circuit 20 described above in connection with fig. 1, with the process beginning with the removal (e.g., by a milling technique) of conductive material from the feed circuit layer to form a feed circuit (e.g., circuit 26 in fig. 1), as indicated at process block 60. In an embodiment, the stripline feed is copper that is not milled away by the AMT milling process.

As indicated by process block 62, an opening is formed around the perimeter of the feed circuit. In a preferred embodiment, the opening is a continuous opening formed by a milling process. Thus, milling (or other) techniques may be used to form an opening in the feed substrate that extends from the first surface to the second, opposite surface of the feed substrate. Such an opening would then be used to form a faraday wall (e.g., faraday wall 32 shown in figure 1) around the feed circuit.

After the openings are formed in the feed substrate, the process proceeds to process block 64 where a process is performed to fill each opening with conductive ink to form conductive signal paths and conductive walls in the feed substrate.

Thus, using an AMT as described above, it can be appreciated that a printed conductive faraday wall can be formed in the same manufacturing step as milling other features and that such faraday walls can be used to confine the electric field in the antenna and feed circuit.

After the helical antenna is formed using the AMT technique of figure 2 and the feed line is formed using the AMT technique of figure 3, the helical antenna so formed and the feed circuit may be connected by a bond technique to provide an integrated helical antenna assembly, such as the assembly 8 described above in connection with figure 1.

Fig. 4-4D below describe structures and techniques to provide a conductive vertical emitter that is additive, inexpensive, and eliminates the electrodeposition of copper in the PCB fabrication process.

Turning now to fig. 4-4D, a technique for forming a conductive (e.g., copper) vertical radiator (e.g., vertical radiator 22 described above in connection with fig. 1) that couples an AMT helical antenna (e.g., helical antenna conductors 14a, 14b described above in connection with fig. 1) to an AMT feed circuit (e.g., feed circuit 26 described above in connection with fig. 1) begins with pre-tinning the bottom trace (feed circuit 26) with solder bumps after the signal traces have been milled out of the double-clad dielectric (fig. 4).

A hole is provided in the top dielectric layer of the feed line and the bonding film to allow room for solder bump reflow in the cavity during bonding (fig. 4A).

A cavity leading to the top layer with the spiral is precut and the assembly is then laminated together (fig. 4B).

A drilling process is performed in which a drill bit or similar structure is inserted into a preformed hole to remove the coalesced film that may have flowed into the area. After the solder mass is drilled, a copper cylinder is inserted until it contacts the solder mass below. It has been found that the diameter of such copper cylinders can be as small as 5 mils, which is much smaller than what can be created by conventional processes (fig. 4C).

A soldering iron with some solder at its end is pressed onto the top of the inserted copper sheet. Due to the short distance, heat is conducted down the length of the copper, reflowing the solder at the feed layer. The solder on the solder remains on the spiral layer, which forms a connection between the inserted copper sheet and the spiral (fig. 4D).

As described herein, a faraday wall is a conductor that provides an electromagnetic boundary "perpendicularly" through a substrate. The faraday walls may be formed by machining a trench through the substrate down to the ground plane and filling the trench with a conductive material, such as a conductive ink applied using additive manufacturing techniques. When the conductive ink is cured, a substantially electrically continuous conductor may be formed. The trenches in which the faraday walls are formed do not have to penetrate or pass through the ground plane. The faraday wall can thus be in electrical contact with the ground plane. Furthermore, the top of the faraday wall may be in electrical contact with another ground plane face, which may be achieved, for example, by slightly overfilling the machined trenches to ensure contact between the conductive ink and the ground plane and/or by applying solder. The position of the faraday wall can be selected according to its effect on the signal transmitted by the feed circuit. In various embodiments, the faraday wall may be positioned to provide isolation without regard to affecting the signal in any particular manner other than providing isolation.

Having described preferred embodiments for illustrating the various concepts, structures and techniques that are the subject of this patent, it will now become apparent to those of ordinary skill in the art that other embodiments can be used that incorporate these concepts, structures and techniques. In addition, elements of different embodiments described herein may be combined to form other embodiments not specifically set forth above.

Accordingly, the scope of this patent is to be considered limited not by the described embodiments, but only by the spirit and scope of the appended claims.