EP0514378A1 - End fed flat antenna - Google Patents
End fed flat antennaInfo
- Publication number
- EP0514378A1 EP0514378A1 EP91900117A EP91900117A EP0514378A1 EP 0514378 A1 EP0514378 A1 EP 0514378A1 EP 91900117 A EP91900117 A EP 91900117A EP 91900117 A EP91900117 A EP 91900117A EP 0514378 A1 EP0514378 A1 EP 0514378A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- antenna
- planar
- conductive
- antenna element
- substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
- G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
- G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
- G06K19/0672—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with resonating marks
- G06K19/0675—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with resonating marks the resonating marks being of the surface acoustic wave [SAW] kind
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/08—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes
- G06K7/082—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors
- G06K7/083—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors inductive
- G06K7/086—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors inductive sensing passive circuit, e.g. resonant circuit transponders
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
- H01Q9/04—Resonant antennas
- H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole
- H01Q9/28—Conical, cylindrical, cage, strip, gauze, or like elements having an extended radiating surface; Elements comprising two conical surfaces having collinear axes and adjacent apices and fed by two-conductor transmission lines
- H01Q9/285—Planar dipole
Definitions
- the present invention related to a flat (planar) antenna of the dipole type which is arranged to be supplied with an electrical signal, and/or to produce an electrical signal at one end.
- An antenna of the type to which the present invention relates may be contained in a transponder of a "passive interrogator label system".
- a “passive interrogator label system”, so-called, is a radar system utilizing transponders which are capable of receiving an interrogating first signal, processing this singal and transmitting a second signal in reply that is derived from the first signal and contains encoded information. Because the encoded information normally includes an identification code that is unique to each transponder, and because the transponders of such a system are relatively light weight and small and may be easily attached to other objects to be identified, these transponders are sometimes referred to as "labels". Furthermore, the transponders, which may be implemented by SAW devices, carry no self-contained power source, such as a battery, that must be periodically replaced. Consequently, these transponders are denominated as being “passive”; hence the name “passive interrogator label system” .
- a passive interrogator label system includes an "interrogator" for transmitting a first radio frequency signal; at least one passive transponder which receives this first signal, processes it, and sends back a second radio frequency signal containing encoded information; and a receiver, normally located next to the interrogator, for receiving the second signal and decoding the transponder encoded information.
- the passive transponder comprises a SAW device and a dipole antenna, which is either electrically or inductively coupled to the SAW transducers on the SAW device.
- the dipole antenna may be formed by either printing conductive ink (e.g. silver) on a substrate in the prescribed antenna pattern, or by stamping a metal foil into the size and shape of the antenna pattern, and bonding this foil by heat and pressure to the substrate (e.g. a polyeth line coated Mylar sheet) .
- the antenna with its substrate is therefore relatively flat and thin and, depending upon the radio frequency of operation, is relatively modest in its lateral dimensions. For example, the antenna characteristics required for this application, operating at a frequency of approximately 915 MHz. , determine that the antenna be physically approximately one inch wide and three inches long.
- the SAW device, to which the antenna is coupled is also placed on the substrate to form the complete assembly or "label".
- the dipole antenna with the SAV7 device mounted between the dipoles, is satisfactory for most ID tap applications, it would be advantageous, in some applications, to locate the SAW device at one end of the antenna. Such arrangement would simplify packaging the SAW device - antenna combination (label) and would reduce the effect on the label of an adjacent physical body.
- a planar, conductive antenna element having a first end, a second end and a substantially linear portion extending from the first end toward the second end; and (2) a planar, conductive and substantially linear coupling element extending adjacent to, and in parallel with, linear portion of the antenna element.
- This coupling element has a third end arranged adjacent to the first end of the antenna element and a fourth end located between the first and second ends of the antenna element.
- a SAW device or other signal source or sink may be electrically coupled between the first end of the antenna element and the third end of the coupling element to provide an electrical signal to and/or receive and electrical signal from the antenna.
- this source or sink comprises an inductive loop connected between the aforementioned first end and the third end for transmitting and/or receiving an inductively coupled input/output signal to and/or from the antenna.
- Fig. 1 is a representational diagram of a dipole antenna.
- Fig. 2 is a representational diagram of a dipole antenna with a quarter wave feedline.
- Figs. 3a, 3b and 3c are diagrams of a dipole antenna with a quarter wave feedline progressively collapsed toward one dipole.
- Figs. 4-10 are diagrams of antennas in accordance with various preferred embodiments of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS
- Fig. 1 illustrates a typical dipole antenna 10 comprising separate antenna elements 12 and 14.
- a signal source or sink 16 i electrically connected to the inner endsl ⁇ and 20 of the dipole elements 12 and 14, respectively, for supplying a signal to, or receiving a signal from the antenna 10.
- Fig. 2 shows how the dipoles may be supplied via a quarter wave transmission line 22 formed by parallel conductive bars 24 and 26 spaced apart by a gap width G and having a length /4, where is the electrical wavelength at the frequency of operation of the antenna.
- the significant variables in the design of an RF transmission line are the length of the line, the gap width and the dielectric found in the gap.
- Figs. 3a, 3b and 3c illustrate how the quarter wave transmission line may be collapsed into one dipole so that the antenna may be electrically connected to a signal source or sink arranged at one end.
- the transmission line may be folded toward one (the lefthand) dipole; as shown in Fig. 3c, the feed line and the lefthand dipole may be collapsed into a single bar. If the dipole is the same length as the transmission line, the apparent signal source or sink is at the center of the antenna.
- the antenna shown in Fig. 3 thus comprises a planar, conductive antenna element 14 and 24 having a first end 30, a second end 32 and a linear portion 24 extending from the first end 30 toward the second end 32.
- the antenna includes a planar, conductive linear coupling element 26 which extends adjacent to, and in parallel with, the linear portion 24 of the antenna element.
- the coupling element has third end 34 arranged adjacent to the first end 30 of the antenna element and a fourth end 36 located between the first and second ends 30 and 32, respectively, of the antenna element.
- the signal source or sink 16 is electrically connected between the first end 30 of the antenna element and the third end 34 of the coupling element.
- Figure 4 shows how a signal source or sink may be inductively coupled to an end fed antenna according to the present invention.
- the signal source/sink 16 is electrically connected to an inductive loop 38 which, in turn, is inductively coupled to a partial loop 40 connected between the first end 30 and the third end 34 of the antenna.
- Fig. 5 illustrates an antenna with a meander portion 42 extending from the linear portion 24 of the antenna element. This meander portion adjusts the resonant length of the s ructure.
- Fig. 6 shows an antenna which has been enlarged to its maximum dimensions on a card-like, non-conductive substrate 44.
- the resonant length of the structure is adjusted by providing a "tail" 46.
- Fig. 7 shows an antenna similar to that of Fig. 5 arranged on a non-conductive substrate 44.
- the antenna is inductively coupled to a SAW device 47 which is placed directly over the antenna's inductive loop 40.
- the SAW device 47 incorporates a complementary inductive loop for coupling a signal to and from the antenna.
- Fig. 8 shows still another antenna configuration, which is presently the best mode for practicing the invention.
- This antenna is similar to that of Figs. 5 and 7 but includes an additional planar, conductive, meander element 48, disposed on the substrate surface, having fifth and sixth ends 50 and 52, respectively.
- the fifth end 50 is electrically coupled to the first end 30 of the linear portion 24 of the antenna element.
- This meander element serves to increase the inductance of the antenna, thereby tuning the antenna to the inductively coupled source or sink.
- Figs. 9 and 10 show additional antenna structures according to the present invention which include reflectors 54 and 56, respectively. These reflectors improve the isolation of the antenna from other reflecting elements in the vicinity.
- the present invention contemplates a planar (flat) antenna incorporating a transmission line that permits direct electrical connection (or inductive coupling) to one end of the antenna.
- the transmission line is formed of two legs: a linear portion of the antenna element itself and a separate, linear coupling element.
- This transmission line operates to contain a non-radiating field within the interior of the antenna (between the two legs) while permitting radiation to occur on the outside of the antenna.
- the antenna is driven from one end, the antenna operates as if the signal source or sink were connected at its center.
Abstract
Une antenne plate est disposée sur un substrat non-conducteur possédant une surface plane et exposée. L'antenne comprend un élément d'antenne conductif plat fixé sur la surface du substrat. Ledit élément d'antenne possède une première extrémité, une deuxième extrémité, et un segment principalement linéaire placé entre lesdites première et seconde extrémités. Un élément de couplage plat, conductif et principalement linéaire est disposé sur la surface du substrat et est placé à côté et en parallèle avec le segment linéaire de l'antenne. Ledit élément de couplage possède une troisième extrémité disposée de façon adjacente à la première extrémité de l'antenne, et une quatrième extrémité située entre la première et la seconde extrémité de l'antenne. Un connecteur électrique est relié à la première et à la troisième extrémités de manière à fournir de l'énergie électrique à l'antenne et/ou à en recevoir de l'énergie électrique.A flat antenna is disposed on a non-conductive substrate having a planar and exposed surface. The antenna includes a flat conductive antenna element attached to the surface of the substrate. Said antenna element has a first end, a second end, and a mainly linear segment placed between said first and second ends. A flat, conductive and mainly linear coupling element is arranged on the surface of the substrate and is placed next to and in parallel with the linear segment of the antenna. The coupling element has a third end disposed adjacent to the first end of the antenna, and a fourth end located between the first and second ends of the antenna. An electrical connector is connected to the first and third ends so as to supply electrical energy to the antenna and / or to receive electrical energy therefrom.
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US43423389A | 1989-11-13 | 1989-11-13 | |
US434233 | 1989-11-13 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0514378A1 true EP0514378A1 (en) | 1992-11-25 |
EP0514378A4 EP0514378A4 (en) | 1993-02-24 |
Family
ID=23723388
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19910900117 Withdrawn EP0514378A4 (en) | 1989-11-13 | 1990-11-13 | End fed flat antenna |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0514378A4 (en) |
CA (1) | CA2068521C (en) |
WO (1) | WO1991007785A1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3689929A (en) * | 1970-11-23 | 1972-09-05 | Howard B Moody | Antenna structure |
US4259673A (en) * | 1979-06-05 | 1981-03-31 | Harold Guretzky | Stub matched antenna and method of feeding same |
US4400702A (en) * | 1980-05-13 | 1983-08-23 | Hiroki Tanaka | Shortened antenna having coaxial lines as its elements |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE623608C (en) * | 1933-11-21 | 1900-01-01 | ||
US4138681A (en) * | 1977-08-29 | 1979-02-06 | Motorola, Inc. | Portable radio antenna |
US4642640A (en) * | 1983-04-25 | 1987-02-10 | Sensormatic Electronics Corporation | Signal receptor-reradiator and surveillance tag using the same |
US4737789A (en) * | 1986-12-02 | 1988-04-12 | X Cyte, Inc. | Inductive antenna coupling for a surface acoustic wave transponder |
US4800392A (en) * | 1987-01-08 | 1989-01-24 | Motorola, Inc. | Integral laminar antenna and radio housing |
-
1990
- 1990-11-13 EP EP19910900117 patent/EP0514378A4/en not_active Withdrawn
- 1990-11-13 WO PCT/US1990/006614 patent/WO1991007785A1/en not_active Application Discontinuation
- 1990-11-13 CA CA002068521A patent/CA2068521C/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3689929A (en) * | 1970-11-23 | 1972-09-05 | Howard B Moody | Antenna structure |
US4259673A (en) * | 1979-06-05 | 1981-03-31 | Harold Guretzky | Stub matched antenna and method of feeding same |
US4400702A (en) * | 1980-05-13 | 1983-08-23 | Hiroki Tanaka | Shortened antenna having coaxial lines as its elements |
Non-Patent Citations (1)
Title |
---|
See also references of WO9107785A1 * |
Also Published As
Publication number | Publication date |
---|---|
CA2068521A1 (en) | 1991-05-14 |
WO1991007785A1 (en) | 1991-05-30 |
CA2068521C (en) | 2000-01-18 |
EP0514378A4 (en) | 1993-02-24 |
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Legal Events
Date | Code | Title | Description |
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
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17P | Request for examination filed |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 19990304 |