Source: http://www.google.com/patents/US8040291?dq=6,757,682
Timestamp: 2016-05-05 03:22:06
Document Index: 628070929

Matched Legal Cases: ['art 28', 'art 28', 'art 28', 'art 28', 'art 28', 'art 28']

Patent US8040291 - F-inverted compact antenna for wireless sensor networks and manufacturing method - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsAn F-inverted compact antenna for ultra-low volume Wireless Sensor Networks is developed with a volume of 0.024λ�0.06λ�0.076λ, ground plane included, where λ is a resonating frequency of the antenna. The radiation efficiency attained is 48.53% and the peak gain is −1.38 dB. The antenna is easily...http://www.google.com/patents/US8040291?utm_source=gb-gplus-sharePatent US8040291 - F-inverted compact antenna for wireless sensor networks and manufacturing methodAdvanced Patent SearchPublication numberUS8040291 B2Publication typeGrantApplication numberUS 12/470,905Publication dateOct 18, 2011Filing dateMay 22, 2009Priority dateMay 23, 2008Fee statusPaidAlso published asUS20100026605Publication number12470905, 470905, US 8040291 B2, US 8040291B2, US-B2-8040291, US8040291 B2, US8040291B2InventorsBo Yang, Felice M. Vanin, Xi Shao, Quirino Balzano, Neil GoldsmanOriginal AssigneeUniversity Of MarylandExport CitationBiBTeX, EndNote, RefManPatent Citations (5), Classifications (9), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetF-inverted compact antenna for wireless sensor networks and manufacturing method
US 8040291 B2Abstract
An F-inverted compact antenna for ultra-low volume Wireless Sensor Networks is developed with a volume of 0.024λ�0.06λ�0.076λ, ground plane included, where λ is a resonating frequency of the antenna. The radiation efficiency attained is 48.53% and the peak gain is −1.38 dB. The antenna is easily scaled to higher operating frequencies up to 2500 MHz bands with comparable performance. The antenna successfully transmits and receives signals with tolerable errors. It includes a standard PCB board with dielectric block thereon and helically contoured antenna wound from a copper wire attached to the dielectric block and oriented with the helix axis parallel to the PCB. The antenna demonstrates omnidirectional radiation patterns and is highly integratable with WSN, specifically in Smart Dust sensors. The antenna balances the trade offs between performance and overall size and may be manufactured with the use of milling technique and laser cutters.
1. An F-inverted compact antenna for ultra low volume Wireless Sensor Networks (WSN), comprising:
a ground plane board,
a dielectric block attached to a surface of said ground plane board at a predetermined location thereof, and
a helically contoured member attached to said dielectric block and disposed with an axis of said helically contoured member extending substantially in parallel to said surface of said ground plane board, said helically contoured member including a pre-wound wire portion having a first end and a second end and a plurality of coils between said first and second ends, and a wire part coupled at a tapping end thereof to said pre-wound wire portion at a predetermined tapping point,
wherein said first end of said pre-wound wire portion and another end of said wire part opposite to said tapping end thereof are coupled respectively to feeding and shorting points of said compact antenna.
2. The compact antenna of claim 1, wherein said helically contoured member is formed from a wire of a diameter approximating in the range between 0.5 mm and 0.8 mm.
3. The compact antenna of claim 1, wherein said wire is made of copper.
4. The compact antenna of claim 1, wherein said tapping point is located a predetermined distance ranging between 5 mm and 13.57 mm from said feeding point.
5. The compact antenna of claim 1, wherein said ground plane board has dimensions in the range below 10-20 mm�12-25 mm.
6. The compact antenna of claim 1, further comprising a connector coupled to said antenna through a feeding pin, wherein said ground plane board has a feeding opening formed therein, wherein said feeding pin of said connector extends through said feeding opening, and wherein said first end of said pre-wound wire portion is coupled to said feeding pin.
7. The compact antenna of claim 1, wherein said ground plane board is fabricated from FR4 with a layer of copper plate embedded therein.
8. The compact antenna of claim 1, wherein said another end of said wire part is shorted to said ground plane board.
9. The compact antenna of claim 1, wherein said dielectric block is shaped with a plurality of receiving structures of dimensions and disposition cooperating with dimensions and shape of said helically contoured member, each of said plurality of coils of said pre-wound wire portion being secured in a respective one of said receiving structures.
10. The compact antenna of claim 9, wherein said receiving structures are formed as grooves extending substantially in parallel each to the other.
11. The compact antenna of claim 9, wherein said receiving structures are formed as channels passing through said dielectric block, each channel receiving a respective one of said plurality of coils of said pre-wound helically contoured member.
12. The compact antenna of claim 1, wherein said pre-wound wire portion is formed from a wire having a length depending on the bandwidth of said compact antenna.
13. The compact antenna of claim 6, wherein said connector is an SMA connector.
14. The compact antenna of claim 1, wherein for the operating frequency of said compact antenna in the range of 906 MHz-926 MHz, a volume occupied by said compact antenna is below approximately 0.06λ�0.076λ�0.024λ, wherein λ is a resonating wavelength of said compact antenna.
15. The compact antenna of claim 14, wherein a spacing between said coils is approximately 2.5 mm.
16. The compact antenna of claim 1, wherein for the operating frequency in the range of 2.2-2.45 GHz, a volume occupied by said compact antenna is below approximately 10 mm�10 mm�10 mm.
17. The compact antenna of claim 12, wherein the length of said wire is in the range approximately 30 mm-50 mm for the operating frequency in the range of 2.2 GHz-2.45 GHz.
18. A method for manufacturing an F-inverted compact antenna for ultra-low volume Wireless Sensor Networks (WSN), comprising the steps of:
providing a ground plane board of predetermined dimensions compatible with the ultra-low volume WSN,
forming a dielectric block having a plurality substantially parallel receiving structures of predetermined dimensions, and spaced predetermined distance one from another,
attaching said dielectric block to a surface of said ground plane board at a predefined position thereof,
pre-winding a wire of a predetermined length and diameter into a helically contoured member having a plurality of coils coordinated with said receiving structures of said dielectric block, said helically contoured member having a first end and a second end, coupling a tapping end of a wire part of a predetermined length to a predetermined tapping location of a respective one of said plurality of coils,
attaching said helically contoured member to said dielectric block with the axis of said helically contoured member extending substantially in parallel to said surface of said ground plane board, wherein each of said plurality of coils of said helically contoured member is received in a respective one of said plurality of receiving structures of said dielectric block, and
coupling said first end of said helically contoured member to a feeding point, and shorting said wire part to said ground plane board.
20. The method of claim 18, wherein said compact antenna occupies a volume on a mm scale, further comprising the steps of:
integrating said compact antenna with an ultra small smart sensor network transceiver. Description
First, in each WSN transceiver node, all components, such as sensor, antenna, battery, transceiver integrated circuit (IC), as well as the reference ground plane (normally a printed circuit board) for IC and antenna are to be stacked or integrated in a package with a total volume of only a few mm3 to one cm3, where only a fraction of this volume is left for an antenna. The millimeter or centimeter scale dimensions are often much less than a quarter wavelength at the operating frequency (i.e., 0.1λ or less). For example, in conventional ESA designs, a ground plane with a minimum quarter wavelength dimension is often necessary for proper performance. In the ISM bands (916/828/433 MHz), this ground plane size is between 8 to 16 cm. Though this is a reasonable size to be fit within a cell phone or a PDA's housing, it is too large to be integrated into SmartDust sensor nodes in WSN communication package, whose node size is on the order of a few cm3 or smaller. A package with a low height and a large ground plane area is not suitable for WSN applications. In WSN, the ground plane size must be decreased as well as the height of the antenna. This requires new designs to reduce both factors and keep the antenna highly functional.
Thus there is a need in SmartDust WSN applications for an antenna which occupies a volume no larger than 20 mm�25 mm�8 mm, which is 0.06λ�0.076λ�0.024λ (for a particular operating frequency of 916 MHz), and which has an omnidirectional a radiation pattern in order to transmit to and detect signals from random directions. The desired compact antenna also must be optimized for maximum efficiency and bandwidth, since small antennas inherently have high Q or low efficiency.
It is an overall object of the present invention to provide an F-inverted compact antenna built for specific Wireless Sensor Network (WSN)/Smart Dust applications in which the antenna occupies a volume no larger than 20 mm�25 mm�8 mm, e.g. 0.06λ�0.076λ�0.024λ for a particular ISM (Industrial, Scientific and Medical) band of 916 MHz and which is scalable for even higher operating frequencies such as 2.2-2.5 GHz).
The dimensions of the compact antenna in question, e.g., the volume occupied thereby, are adapted to be compatible with ultra-low volume Wireless Sensor Networks, for example SmartDust sensors, and therefore do not exceed mm or maximum cm scale. The dimensions of the compact antenna dependent on a desired operational frequency are easily scalable to the desired operational frequency. For example, for the operating frequency in the range of 906 MHz-926 MHz, a volume occupied by the compact antenna is in the range of 0.06λ�0.076λ�0.024λ, where λ is a resonating wavelength of the compact antenna.
The dielectric block to which the helically contoured member is attached is shaped as a preferably rectangular member from Teflon or Lexan� material and has a plurality of receiving structures, such as parallel grooves or channels penetrating through the dielectric block, and formed with predetermined dimensions and at locations in full cooperation with the dimensions of the helically contoured member, such as the diameter of the wire used, pitch between the coils, dimensions of the coils, etc. For 916 MHz operating frequency, the dielectric block may have dimensions in the range below 4-5 mm�1.5-2.5 mm�15 mm, and may be positioned approximately 4-5 mm from an edge of the ground plane board. A spacing between the coils in the helically contoured member may be approximately 2.5 mm. In order to adopt the compact antenna in question to the operating frequency range of 2.2-2.45 GHz, the dimensions of the compact antenna may be scaled. It was found that in this higher operational frequency arrangement, it is desired to provide a volume occupied by the compact antenna in the range of approximately 10 mm�10 mm�10 mm.
With the above-listed guidelines, a novel F-inverted compact antenna (FICA) 10, shown in FIGS. 1, 2A-2D and 6G has been designed. The novel compact antenna 10 includes a ground plane board 12, a dielectric block 14 attached to the ground plane board 12 at a predetermined position on the surface 16 thereof, and a helically contoured member 18 formed of a wire 20 The helically contoured member 18 comprises a pre-wound wire portion 22 which has two ends 24 and 26, and a wire part 28 soldered to the pre-wound wire portion 22 at a predetermined tapping point 34. The wire part 28 is soldered to the pre-wound wire portion 22 at a predetermined location (tapping point) 34 defined by a tap distance which is selectively calculated, as will be further discussed. The wire part 28 is soldered at the tapping end 30 thereof to the pre-wound wire portion 22. An opposite (shorting) end 32 of the wire 28 is shorted to the ground plane board 12 as will be disclosed in detail further herein.
� (diameter of the feeding opening)
mm (fixed)
� (diameter of the shorting opening)
d1 (distance between centers of the
feeding and shorting openings)
PCBX (length)
PCBY (width)
d2 (distance from the center of the
feeding opening to an edge of the PCB)
d3 (distance from the center of the
feeding opening to another edge of the
PCBH (thickness of the PCB)
0.508 mm~3.175 mm
(Depends on Advanced Circuit
In a grooved modification, the dielectric block 14 has substantially parallel grooves 44, the dimensions and positioning of which are commensurate with the design of the helically contoured member 18. Specifically, the width of the grooves 44 corresponds to the diameter of the wire 20 used for the helically contoured member 18, while the length of the grooves (coinciding with the width of the dielectric block 14) is selected in accordance with the dimensions of the coils 46 of the helically contoured member 18. The distance between the grooves 44 corresponding to the pitch between the coils 46. The dielectric supporting block may be made of Lexan�, Teflon, or other suitable dielectric material. Milling technique and/or laser cutting may be used in fabrication of the dielectric block 14. Table 2 represents the parameters of the dielectric block 14 for a 2.2/2.45 GHz antenna of the present invention presented in FIGS. 3A-3B. These parameters are variable for other operating frequencies as will be presented further herein. The location of the dielectric block 14 on the PCB 12 may be defined at a distance 4-5 mm from the edges thereof.
Parameters for Lexan� GE Block
SlotTopHeight
Parameters for Pre-Wound Wire
mm to 4 mm (note1)
Table 4 represents parameters for the wire part 28. The length of L13 depends on the easiness to solder to the shorting pin 42, but it is preferably not longer than 4 mm. The tapping position 34 defined in FIG. 4D, is one of the most important parameters for the compact antenna 10, which is defined as: tapping distance=L1+L2+t. For the dimensions shown in Table 4, the tapping distance measured from the feeding point ranges from 5 mm to 13.57 mm. The results of the study performed to find the optimal tapping position, will be presented further herein.
0.75 mm to 4 mm
Length varies; should match the length of tap
(L 14 = sqrt((d1 − tap){circumflex over ( )}2 + L2{circumflex over ( )}2))
(So L14 varies between 4.25 mm to 5.57 mm)
As presented further in FIG. 6D, the dielectric block 14, for example Lexan� block with the grooves, is attached to the surface 16 of the ground plane board 12 at a predetermined distance (4-5 mm) from the edges. The dielectric supporting blocks are manufactured either with holes on the sides or grooves separated by certain pitches. The wire 20 is then pre-wound to a helix 22 in accordance to the pitches defined in the dielectric block either between the holes on the side thereof or between the grooves. Further, the pre-wound wire portion (helix) 22 and the wire part 28 shown in FIG. 6E are soldered together at the tapping point 34, as shown in FIG. 6F, and the entire helically contoured member 18 is attached to the dielectric block 14 by inserting the coils 46 into the grooves 44. The feeding end 24 of the pre-wound wire portion 22 and the shorting end 32 of the wire part 28 are soldered respectively to the feeding pin 40 and the shorting pin 42, as shown in FIG. 6G.
Several samples of the compact antenna were built for the range of 916 MHz operating frequency, and the antenna was scaled to higher frequencies in the range of up to 2500 MHz. As an example only, but not to limit the dimensions of the compact antenna to the specific size shown in FIGS. 2A-2D, a 916 MHz FICA was fabricated with the total volume (including the ground plane) of approximately 8 mm�20 mm�25 mm. Other dimensions of the antenna are also within the scope of the present invention as long as they are compatible with the WSN applications.
The FICA structure simulated with Ansoft HFSS is shown as an inset in FIG. 7. The ground plane is an FR4 printed circuit board (PCB) with a size of 20 mm�25 mm, which is constrained by the circuit board dimension imposed from Smart Dust WSN requirement. A 0.8 mm diameter copper wire is wound as a helix into a 15 mm�2.5 mm�5 mm dielectric block made from Lexan� with relative permittivity of 2.96 and loss tangent <0.001. The Lexan� block provides mechanical support to the antenna, which helps to reduce the effect of vibrations.
Another F-inverted compact antenna (FICA) with a reduced size and acceptable gain and bandwidth performance, was built with a 0.5 mm diameter copper wire wound and embedded into a 10 mm�10 mm�6 mm Teflon block with relative permittivity of 2.1. In FIGS. 2A-2B, Pin1 and Pin2, which are the feeding pin and the shorting pin, respectively, are of 7 mm in height. This antenna is fed by a SMA connector through a via in the FR4 ground plane. Ansoft simulations showed that the current densities in both shorting and feeding pins are in phase, so both pins are effective radiating components for the antenna. The position of the feeding pin tap (parameter t in FIG. 4D) was carefully selected. From Ansoft simulations and experiments, it was found that reducing t lowers the resonance frequency, because the antenna effective length increases.
After carefully tuning the tapping point on a very small ground plane (20 mm by 25 mm), the prototyped 916 MHz FICA was measured with an Agilent 8364B Vector Network Analyzer. FIG. 9 shows the measured S11 of the FICA. As one can see, the antenna resonates at 916 MHz. The −10 dB bandwidth is 15 MHz, about 1.6% of its center frequency. The total volume of this antenna is 20 mm�12 mm�7 mm.
5 dBm RF signals were transmitted from the antenna, and the RF power level at the receiving antenna was recorded. First, the gain of two identical half-wave length dipoles was measured. This value was used as the 0 dB gain reference in FIG. 10. One of the dipoles was replaced with the FICA, and the receiving power vs. azimuth angle was measured. In FIG. 10, the pattern of the antenna is shown when the feeding and shorting pins are parallel to the transmit dipole (Eθ, co-polarization), and when the two pins are perpendicular to the dipole (Eθ, cross polarization). It is clear that the antenna has much higher gain for the co-polarization than for the cross polarization. The HFSS simulations showed that the current flowing in the two vertical pins, the feeding and the shorting pin, are in phase. The co-polarized radiation due to these vertical pins is stronger and has a uniform pattern. Measurement and simulation results both indicate that the FICA works as a dipole as opposed to an omnidirectional mode helical antenna.
The measured gain of the FICA is 3.53 dB lower than a standard half wave dipole, which indicates FICA's gain is −1.38 dBi. The antenna efficiency is about 48.53%. Considering that the total volume occupied by this FICA, including the ground plane, is only 2.4% λ�6% λ�7.6% λ, this small antenna is very efficient. A performance comparison of this work to other ESAs is summarized in Table 5.
0.11 λ�
0.2λ � 0.26
0.176 λ�
0.06 λ�
0.11 λ
0.208 λ
0.076 λ
0.026 λ
1.3 � 10−3 λ3 1.4 � 10−3 λ3 1.7 � 10−3 λ3 9 � 10−5 λ3 Bandwidth
2.1% 2.26% 8.3% 2.45% (−3 dB)
Operating frequency 394
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4914450 *Jan 31, 1985Apr 3, 1990The United States Of America As Represented By The Secretary Of The NavyHigh frequency whip antennaUS7295161 *Aug 6, 2004Nov 13, 2007International Business Machines CorporationApparatus and methods for constructing antennas using wire bonds as radiating elementsUS7598915 *Sep 18, 2007Oct 6, 2009Aisin Seiki Kabushiki KaishaBobbin for bar antenna, antenna and door handle for a vehicleUS20020018026 *Aug 2, 2001Feb 14, 2002Mitsumi Electric Co., Ltd.Antenna apparatus having a simplified structureUS20050001769 *Jun 9, 2004Jan 6, 2005Yihong QiMultiple-element antenna with floating antenna element* Cited by examinerClassifications U.S. Classification343/895International ClassificationH01Q9/30Cooperative ClassificationY10T29/49016, H01Q11/08, H01Q9/0421, H01Q9/0471European ClassificationH01Q9/04B7, H01Q11/08, H01Q9/04B2Legal EventsDateCodeEventDescriptionSep 6, 2011ASAssignmentOwner name: UNIVERSITY OF MARYLAND, MARYLANDFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:YANG, BO;VANIN, FELICE M.;SHAO, XI;AND OTHERS;SIGNING DATES FROM 20090820 TO 20090916;REEL/FRAME:026863/0483Apr 3, 2015FPAYFee paymentYear of fee payment: 4RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services