This disclosure relates generally to the field of antennas. More particularly, the disclosure relates to transmission mechanism for conducting electromagnetic energy, particularly suitable for antennas.
Common methods of conducting electromagnetic energy between locations are to use a circuit board with microstrip printed technology or using a metallic wave-guide. The advantage of a circuit board over a waveguide is that it can be produced in higher volumes and is flat. The disadvantage is the loss which is proportional to the distance the high frequency electronic signal travels. The advantage of a metallic wave-guide is that it operates with lower losses, but the disadvantage is that it is neither as thin as a circuit board nor as cost effective.
Some circuit board substrates are designed to have low propagation losses. The typical low loss substrate is a mixture of Teflon and glass. However, these Circuit Boards are more expensive because of the process of pressing the Teflon and glass flat, which requires tremendous pressure.
One problem with many low loss materials like Polytetrafluoroethylene, (commonly called Teflon®), is that the thermal expansion and contraction rates for these materials is very different than that for the conductive metals, which they would otherwise be bonded to. For example, if a copper line is formed on Teflon, the Teflon will expand with temperature at a different rate than the copper, and therefore de-laminate the copper. The current art for dealing with this expansion problem is to load the Teflon material with glass to reduce its coefficient of thermal expansion, along with substantial other processes.
Another problem with many low loss materials like Teflon is that they have low surface energy, making it difficult to bond to a conductive circuit. In many instances, glues, or other adhesives are used and these materials have negative RF propagation factors.
Accordingly, a need exists in the art for improved transmission vehicles for electromagnetic energy, which can be used, e.g., in antennas used for wireless communication.
The following summary of the disclosure is included in order to provide a basic understanding of some aspects and features of the invention. This summary is not an extensive overview of the invention and as such it is not intended to particularly identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented below.
Disclosed embodiments enable a flat and low loss material with the benefits of a circuit board at a much lower cost. In disclosed examples the embodiments are applied to an antenna, but it could be applied to other devices which require high frequency electronic transmission, such as microwaves, radars, LIDAR, etc.
In the disclosed embodiments no glass loading of the substrate material is necessary. The dielectric material, e.g., Teflon®, is free to thermally change size in the x, y and z dimension without any delamination possibility. This is because the copper is not bonded to the dielectric material, but merely maintained in proximate contact, allowing the dielectric material to slide under the copper without affecting the electron flow between the copper and the ground plane.
In some embodiments a film substrate is chemically or mechanically bonded to the conducting circuitry on one side and pressure is applied to the film substrate with a force vector in the direction of the dielectric plate to maintain the dielectric plate and the conductor circuitry attached to the substrate in proximate contact with each other.
In some embodiments the conducting material is chemically or mechanically bonded to one side of the substrate and pressure is applied to the conducting material with a force vector in the direction of the low dielectric material to maintain the low dielectric material and the conductor attached to the substrate in close proximity with each other.
In some embodiments a conducting circuitry is mechanically held between two insulating substrates.
In disclosed embodiments the force vector may be maintained using, e.g., dielectric bolts or dielectric pins.
According to further embodiments, a high performance electro-magnetic transmission system is provided which includes a low dielectric material and two substrate materials in proximate contact with the low dielectric material where at least one of the substrate materials is without a chemical or mechanical bond to the low dielectric material and is mechanically or electrically attached to a conductor material located electrically opposite the low dielectric material.
According to disclosed aspects, a method of fabricating a high performance electro-magnetic transmission line system is provided, comprising: obtaining a substrate; positioning a first conductive circuitry onto a first surface of the substrate; obtaining an insulating plate; positioning a second conductive circuitry onto a first surface of the insulating plate; and, attaching the substrate to the insulating plate. The method may further comprise applying pressure to maintain at least one of the first and second conductive circuitry in proximate contact with the insulating plate. The method may further comprise inserting dielectric pins through the insulating plate.
Other aspects and features of the invention would be apparent from the detailed description, which is made with reference to the following drawings. It should be appreciated that the detailed description and the drawings provides various non-limiting examples of various embodiments of the invention, which is defined by the appended claims.
The accompanying drawings, which are incorporated in and constitute a part of this specification, exemplify the embodiments of the present invention and, together with the description, serve to explain and illustrate principles of the invention. The drawings are intended to illustrate major features of the exemplary embodiments in a diagrammatic manner. The drawings are not intended to depict every feature of actual embodiments nor relative dimensions of the depicted elements, and are not drawn to scale.
Embodiments of the inventive electrical transmission mechanism will now be described with reference to the drawings. Different embodiments or their combinations may be used for different applications or to achieve different benefits. Depending on the outcome sought to be achieved, different features disclosed herein may be utilized partially or to their fullest, alone or in combination with other features, balancing advantages with requirements and constraints. Therefore, certain benefits will be highlighted with reference to different embodiments, but are not limited to the disclosed embodiments. That is, the features disclosed herein are not limited to the embodiment within which they are described, but may be “mixed and matched” with other features and incorporated in other embodiments.
Disclosed embodiments utilize multiple layers of insulating and conductive materials, which are made to be contiguous with each other, therefore creating a low loss high frequency transmission medium. The layers in one example include: a thin film carrier material (e.g., polyimide), a copper circuit, a dielectric plate of low loss material, e.g., Teflon, and a plate of conductive material to act as a ground plane.
In the example of
In some embodiments, the internal assembly of the thin-film carrier 205, conductive circuit 210, dielectric plate 220 and common ground 225 can be aligned and held in lateral alignment. In the example of
While the pins are showed only in one location, such pins could also be combined with the bolts of 250 and placed through the materials of 225, 220 and 210 in such a way to not interfere with the RF properties of the conductive circuit 210 and ground plane 225. In such an embodiment the pins could be made of a similar or matching low dielectric material such as that found in 220 so that the pins may be located near the circuits of 210 without negatively effecting the RF properties of the circuits.
Thus, as can be understood, according to one aspect, an electro-magnetic transmission line system is provided, comprising: a film substrate; a conductive circuit positioned on one surface of the film substrate; a dielectric plate having a first surface contacting the film substrate; and a conductive ground attached to or in proximate contact to a second surface of the dielectric plate. The conductive circuit may be sandwiched between the film substrate and the dielectric plate, and can be attached to the film substrate and not attached to the dielectric plate. A top retaining member may be positioned over the film substrate and a bottom retaining member may be positioned over the conductive ground, and a pressure applicator may apply compressive force to the top retaining member and the bottom retaining member. A plurality of aligners may be configured to maintain lateral alignment between the film substrate and the dielectric plate. The dielectric plate may be made of: Polytetrafluoroethylene, Polyethylene terephthalate, glass fiber impregnated Polypropylene, or other Polypropylene material.
It should be noted that in the embodiments of
In yet another example, illustrated in
The general method of fabricating any of the disclosed embodiments includes forming the conductive circuitry over one surface of a carrier substrate, which is made of an insulative film. The fabrication of the conductive circuitry may be done by, e.g., sputtering deposition, electro or electroless plating, adhering copper lines onto the substrate, etc. Similarly, a conductive common ground is fabricated on one surface of the dielectric plate. The fabrication of the common ground may be done by, e.g., sputtering deposition, electro or electroless plating, adhering copper film onto the dielectric plate, etc. The thickness and material of the dielectric plate is selected according to the frequency and bandwidth of the transmission signal. The film substrate is then placed in contact with the bare surface of the dielectric plate, i.e., the surface opposite the common ground. In one example, e.g.,
On the other hand,
While for clarity the pins are shown at the edges of the image, the pins could also be placed internal to the picture in the quantity necessary to ensure proper alignment in the x, y and z directions.
As also shown in the callout of
As shown in
Thus, according to the embodiment illustrated in
Thus, according to the embodiment illustrated in
An example of an antenna that can utilize the feeding structure disclosed herein can be better understood from the following description of
A top dielectric spacer 805 is generally in the form of a dielectric (insulating) plate or a dielectric sheet, and may be made of, e.g., glass, PET, etc. The radiating patch 810 is formed over the spacer by, e.g., adhering a conductive film, sputtering, printing, etc. At each patch location, a via may be formed in the dielectric spacer 805 and is filled with conductive material, e.g., copper, to form contact 825, which connects physically and electrically to radiating patch 810. A delay line 815 is formed on the bottom surface of dielectric spacer 805 (or on top surface of upper binder 842), and is connected physically and electrically to contact 825. That is, there is a continuous DC electrical connection from the delay line 815 to radiating patch 810, through contact 825. As shown in
The delay in the delay line 815 is controlled by the variable dielectric constant (VDC) plate 840 having variable dielectric constant material 844. While any manner for constructing the VDC plate 840 may be suitable for use with the embodiments of the antenna, as a shorthand in the specific embodiments the VDC plate 840 is shown consisting of upper binder 842, (e.g., glass PET, etc.) variable dielectric constant material 844 (e.g., twisted nematic liquid crystal layer), and bottom binder 846. In other embodiments one or both of the binder layers 842 and 844 may be omitted. Alternatively, adhesive such as epoxy or glass beads may be used instead of the binder layers 842 and/or 844.
In some embodiments, e.g., when using twisted nematic liquid crystal layer, the VDC plate 840 also includes an alignment layer that may be deposited and/or glued onto the bottom of spacer 805, or be formed on the upper binder 842. The alignment layer may be a thin layer of material, such as polyimide-based PVA, that is being rubbed or cured with UV in order to align the molecules of the LC at the edges of confining substrates.
The effective dielectric constant of VDC plate 840 can be controlled by applying AC or DC potential across the VDC plate 840. For that purpose, electrodes are formed and are connected to controllable voltage potential. There are various arrangements to form the electrodes, and several examples will be shown in the disclosed embodiments. In the arrangement shown in
At this point it should be clarified that in the subject description the use of the term ground or common ground refers to both the generally acceptable ground potential, i.e., earth potential, and also to a common or reference potential, which may be a set potential or a floating potential. Similarly, while in the drawings the symbol for ground is used, it is used as shorthand to signify either an earth or a common potential, interchangeably. Thus, whenever the term ground is used herein, the term common or reference potential, which may be set or floating potential, is included therein.
As with all RF antennas, reception and transmission are symmetrical, such that a description of one equally applies to the other. In this description it may be easier to explain transmission, but reception would be the same, just in the opposite direction.
In transmission mode the RF signal is applied to the feed patch 860 via connector 865 (e.g., a coaxial cable connector). As shown in
In one example the back plane insulator 850 is made of a Rogers® (FR-4 printed circuit board) and the feed patch 860 may be a conductive line formed on the Rogers. Rather than using Rogers, a PTFE (Polytetrafluoroethylene or Teflon®) or other low loss material may be used.
To further understand the RF short (also referred to as virtual choke) design of the disclosed embodiments, reference is made to
In
For efficient coupling of the RF signal, the length of the window 853, indicated as “L”, should be set to about half the wavelength of the RF signal traveling in the feed patch 860, i.e., λ/2. The width of the window, indicated as “W”, should be set to about a tenth of the wavelength, i.e., λ/10. Additionally, for efficient coupling of the RF signal, the feed patch 860 extends about a quarter wave, λ/4, beyond the edge of the window 853, as indicated by D. Similarly, the terminus end (the end opposite contact 825) of delay line 815 extends a quarter wave, λ/4, beyond the edge of the window 853, as indicated by E. Note that distance D is shown longer than distance E, since the RF signal traveling in feed patch 860 has a longer wavelength than the signal traveling in delay line 815.
It should be noted that in the disclosure, every reference to wavelength, indicates the wavelength traveling in the related medium, as the wavelength may change as it travels in the various media of the antenna according to its design and the DC or AC potential applied to variable dielectric matter within the antenna.
As explained above, in the example of
In the embodiment of
As reflected from the above detailed description, a disclosed aspect involves a high performance electro-magnetic transmission system, comprising: an insulating plate comprising a low dielectric material; a first conductive circuit proximate a first surface of the insulating plate; a second conductive circuit proximate a second surface of the insulating plate; and wherein at least one of the first and second conductive circuits is without a chemical or mechanical bond to the insulating plate and is mechanically pressed against the insulating plate. The system may further comprise a substrate abutting the insulating plate, and wherein at least one of the first and second conductive circuits is mechanically or chemically attached to the substrate. The system may further comprise compressive means configured to exert compressive force between the substrate and the insulating plate. The compressive means may comprise a top retaining member positioned over the substrate and a bottom retaining member positioned over the insulating plate, and a pressure applicator applying compressive force to the top retaining member and the bottom retaining member. The insulating plate may be made of: Polytetrafluoroethylene, Polyethylene terephthalate, glass fiber impregnated Polypropylene, or other Polypropylene material
It should be understood that processes and techniques described herein are not inherently related to any particular apparatus and may be implemented by any suitable combination of components. Further, various types of general purpose devices may be used in accordance with the teachings described herein. The present invention has been described in relation to particular examples, which are intended in all respects to be illustrative rather than restrictive. Those skilled in the art will appreciate that many different combinations will be suitable for practicing the present invention.
Moreover, other implementations of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. Various aspects and/or components of the described embodiments may be used singly or in any combination. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
This application claims priority from U.S. Provisional Application No. 62/523,498, filed Jun. 22, 2017 and U.S. Provisional Application No. 62/431,393, filed on Dec. 7, 2016, the disclosures of which are incorporated herein by reference in their entireties.
Number | Date | Country | |
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62523498 | Jun 2017 | US | |
62431393 | Dec 2016 | US |