An antenna array typically operates at a single frequency and can be used for, e.g., Radio Detection And Ranging (RADAR) communication or imaging applications. Antenna arrays are generally made by techniques such as photolithography or nanofabrication.
Embodiments of the subject invention provide novel and advantageous antenna arrays, antenna elements for said arrays, and methods of fabricating and using the same. Antenna arrays can be operated at multiple frequencies, such as at two different frequencies for Radio Detection And Ranging (RADAR) communication and for imaging applications. Each antenna element (e.g., each unit cell having a single antenna element) can include a driven patch that is excited directly and a parasitic patch that is excited by the driven patch. An antenna array (or each unit cell antenna element) can be fabricated using, e.g., a proto laser (such as a U4 proto laser).
In an embodiment, an antenna element can comprise: a substrate; a feeding source disposed on the substrate; a driven patch disposed on the substrate and electrically connected to the feeding source; and a parasitic patch disposed on the substrate and physically separated from the driven patch by a first gap. The driven patch can comprise a main patch and an inset feedline extending in a first direction from the main patch towards the feeding source. A length of the parasitic patch, taken in the first direction, can be smaller than a length of the driven patch, taken in the first direction. The driven patch can be disposed between, in the first direction, the feeding source and the parasitic patch. The antenna element can be a dual-band antenna element. The feeding source can comprise a coplanar waveguide (CPW) comprising a first source patch, a second source patch, and a source microstrip feedline. The source microstrip feedline can be electrically connected to the driven patch (e.g., by being physically connected to the inset feedline). The source microstrip feedline can be disposed between, in a second direction perpendicular to the first direction and parallel to an upper surface of the substrate, the first source patch and the second source patch. The source microstrip feedline can be physically separated from the first source patch by a second gap and physically separated from the second source patch by a third gap. The first source patch can comprise a first through hole and a first via filled in the first through hole, and/or the second source patch can comprise a second through hole and a second via filled in the second through hole. The antenna element can further comprise a bottom conductive layer disposed under the substrate, such that the substrate is disposed between the bottom conductive layer and the drive patch. The first via and/or the second via can each extend through the substrate and be electrically connected to the bottom conductive layer. The second gap can be equal (or about equal) in size to the third gap. The second gap and/or the third gap can each be smaller than the first gap. The first gap can be 10% or less (in distance) than the length of the parasitic patch, taken in the first direction. A width of the parasitic patch, taken in the second direction, can be larger than a width of the driven patch, taken in the second direction. The driven patch can further comprise: a first extension portion extending in the first direction from the main patch towards the feeding source, and being physically spaced apart from the feeding source; and a second extension portion extending in the first direction from the main patch towards the feeding source, and being physically spaced apart from the feeding source. The inset feedline can be physically spaced apart, in the second direction, from the first extension portion by a first inner cutout portion and from the second extension portion by a second inner cutout portion. The driven patch can further comprise: a first outer cutout portion on a first side thereof facing the feeding source; and a second outer cutout portion on the first side thereof. The inset feedline can be disposed between, in the second direction, the first outer cutout portion and the second outer cutout portion. An upper surface of the feeding source, an upper surface of the driven patch, and/or an upper surface of the parasitic patch can all be coplanar with each other. An upper surface of the first source patch and an upper surface of the second source patch can be coplanar with each other. The antenna element can be configured to operate at two frequencies at the W band (e.g., a first frequency of 78 gigahertz (GHz) and a second frequency of 94 GHz).
In another embodiment, an antenna array can comprise: a plurality of unit cell antenna elements, each unit cell antenna element being an antenna element as described herein (e.g., having any or all of the features described in the previous paragraph). The antenna array can be configured to operate at two frequencies at the W band (e.g., a first frequency of 78 GHz and a second frequency of 94 GHz). The feeding source of each unit cell antenna element can be electrically connected to the feeding source of each other unit cell antenna element, forming a feed network (e.g., a corporate feed network). For example, the source microstrip feedline of each unit cell antenna element can be physically connected with the source microstrip feedline of at least one other unit cell antenna element. The substrate of each unit cell antenna element can be shared with the substrate of every other unit cell antenna element, forming a single, monolithic substrate of the antenna array.
In another embodiment, a method of fabricating an antenna element can comprise: using a proto laser machine to fabricate a feeding source, a driven patch, and a parasitic patch on a substrate, the feeding source comprising two through holes extending therethrough; and performing extrusion plating with a conductive material (e.g., a metal material) to form two vias in the two through holes, respectively. The antenna element can be an antenna element as described herein (e.g., having any or all of the features described in the paragraph preceding the previous paragraph). The conductive material can be, for example, a metal paste (e.g., a metal paste comprising silver, gold, copper, aluminum, platinum, or similar).
Embodiments of the subject invention provide novel and advantageous antenna arrays, antenna elements for said arrays, and methods of fabricating and using the same. Antenna arrays can be operated at multiple frequencies, such as at two different frequencies for Radio Detection And Ranging (RADAR) communication and for imaging applications. Each antenna element (e.g., each unit cell having a single antenna element) can include a driven patch that is excited directly and a parasitic patch that is excited by the driven patch. Slots (e.g., gaps between conducive material) can be included to reduce the higher-order current in the parasitic patch.
The feeding source can be, for example, a coplanar waveguide (CPW)-based feeding source and can include a grounded CPW (GCPW). The GCPW can include two coplanar source patches 121 (i.e., the upper surface of each source patch 121 is in the same plane as the other source patch 121) and a source microstrip feedline 122. Each source patch 121 can include a grounded via 123, which can be formed in a through hole 125 through the respective source patch 121. The grounded via 123 can comprise a conductive material (for example, a metal (e.g., silver (Ag), aluminum (Al), copper (Cu), or similar), such as a metal paste). The grounded vias 123 can be electrically connected to the bottom layer conductor. Gaps (or slots) can be formed between the source microstrip feedline 122 and each source patch 121 (the gap between the microstrip feedline 122 and the leftmost source patch 121 is labeled in
The driven patch 130 can include a main patch 131 and an inset feedline 133 (e.g., an inset microstrip feedline) connected directly to the main patch 131 and extending towards the feeding source 120 (e.g., in the y-direction as depicted in the figures). The main patch 131 can have, for example, a polygonal shape, such as a rectangular shape (in a cross-section taken parallel to the upper surface of the substrate 110 (i.e., in the x-y plane as depicted in the figures)). The driven patch 130 can be electrically connected to the feeding source 120, such as by direct physical connection between the inset feedline 133 and the source microstrip feedline 122. In some embodiments, the driven patch 130 can have two inner cutout portions 134 where material of the driven patch 130 is absent, thereby forming two extension portions 132 extending towards the feeding source 120 (e.g., in the y-direction as depicted in the figures) but physically separated from the feeding source 120. The driven patch 130 can further include two outer cutout portions 135 where material of the driven patch 130 is absent, thereby resulting in the extension portions 132 being thinner and conserving material of the driven patch 130. Though the outer cutout portions 135 are depicted in
The parasitic patch 140 can be disposed on an opposite side of the driven patch 130 as the feeding source 120 is. That is, the parasitic patch 140 can be disposed on a side of the driven patch 130 having the radiating edge (of the driven patch 130). The parasitic patch 140 can be physically separated from the driven patch 130 by a gap (labeled “gp” in
At least two of the respective upper surfaces of the driven patch 130, the parasitic patch 140, the source microstrip feedline 122, and the source patches 121 can be disposed in the same plane as each other. In some embodiments, all of the respective upper surfaces of the driven patch 130, the parasitic patch 140, the source microstrip feedline 122, and the source patches 121 can be disposed in the same plane as each other.
In an embodiment, any antenna element (e.g., unit cell having a single antenna element) (e.g., a unit cell comprising a single antenna element) or an entire antenna array can be fabricated using a proto laser (e.g., a U4 proto laser machine). Compared to related art techniques (e.g., photolithography and nanofabrication), which require a lot of wait time to fabricate a small volume, a proto laser is much faster. An extrusion plating method (e.g., a low-cost extrusion plating method) can be used to plate the via 123.
The dual-band tuning can be implemented using a parasitic patch excitation technique. The driven patch can be excited directly (by the feeding source), and the parasitic patch 140 can be excited by driven patch 130. Gaps can be included to reduce the higher-order current in the parasitic patch 140. The gaps can include, for example, a first gap between the parasitic patch 140 and the driven patch 130 (labeled “gp” in
An antenna array can comprise an array of antenna elements, where each antenna element is as described herein (see also
In some embodiments, the antenna array may have a single substrate that is shared by all antenna elements. The antenna array may also have a single bottom conductor that is shared by all antenna elements. The respective feeding sources 120 of the antenna elements 100 can all be electrically connected to each other (e.g., the respective the source microstrip feedlines 122 of the antenna elements 100 can all be electrically connected to each other). For example, the source microstrip feedline 122 of each antenna element 100 can be physically connected to the source microstrip feedline 122 of at least one other antenna element 100 of the antenna array.
When ranges are used herein, such as for dose ranges, combinations and subcombinations of ranges (e.g., subranges within the disclosed range), specific embodiments therein are intended to be explicitly included. When the term “about” is used herein, in conjunction with a numerical value, it is understood that the value can be in a range of 95% of the value to 105% of the value, i.e. the value can be +/−5% of the stated value. For example, “about 1 kg” means from 0.95 kg to 1.05 kg.
A greater understanding of the embodiments of the subject invention and of their many advantages may be had from the following examples, given by way of illustration. The following examples are illustrative of some of the methods, applications, embodiments, and variants of the present invention. They are, of course, not to be considered as limiting the invention. Numerous changes and modifications can be made with respect to embodiments of the invention.
A single antenna element as depicted in
Referring to
The GCPW was aligned to a ground-signal-ground (GSG) probe of an anechoic chamber to measure the radiation pattern of the antenna. The size of the GCPW was chosen due to the fixed GSG probe dimension so that it could measure the antenna pattern properly. The input impedance at the driven patch was calculated as 73 Ohms (Ω). The planar dual-band antenna was implemented at the frequencies of 78 GHz and 94 GHz in order to be useful for RADAR communication and imaging applications.
At 78 GHz, the driven patch radiates but, due to its smaller length (compared to the driven patch), the parasitic patch does not contribute to the radiation. At 94 GHz, the radiation pattern is directional. The driven patch contributes to generating the higher order mode. The corners of the driven patch are cut out close to the inset feedline (to give the outer cutout portions) in order to reduce the higher order mode.
The minimum trace size in the antenna element was 25 so it is very difficult to find processes in the art capable of such a small trace. The antenna element was fabricated using a U4 proto laser machine at Florida International University (FIU) in Miami, FL. A template for thick Rogers 3003 substrate was optimized. In order to do this, the laser power, frequency, overlay speed, and cut repetition is optimized. After fabricating the antenna element including the through holes in the source patches, the vias were formed. Via plating methods (e.g., using a plating machine such as a Leiterplatten-Kopierfrasen (LPKF) machine) can be expensive, and with the through hole diameter being 0.2 mm, they were difficult to see with the naked eye. The via filling process was done under a microscope machine using Ag paste by an extrusion method (see also
A simulation was run on the antenna element to simulate its reflection coefficient (S11) across different frequencies and to determine its realized gain at different zenith angles (θ). The realized gain was determined at azimuthal angles (φ) of 0 degrees and 90 degrees for frequencies of 78 GHz and 94 GHz.
Referring to
It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application.
All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.
This invention was made with government support under 80NSSC19K1674 awarded by the National Aeronautics and Space Administration. The government has certain rights in the invention.
Number | Name | Date | Kind |
---|---|---|---|
11539139 | Cheng | Dec 2022 | B1 |
20040183736 | Sato | Sep 2004 | A1 |
20130169503 | Fakharzadeh Jahromi | Jul 2013 | A1 |
20190067834 | Park | Feb 2019 | A1 |
20230006349 | Lee | Jan 2023 | A1 |