WO2006080892A1 - Antenne a plaque - Google Patents

Antenne a plaque Download PDF

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Publication number
WO2006080892A1
WO2006080892A1 PCT/SE2006/000133 SE2006000133W WO2006080892A1 WO 2006080892 A1 WO2006080892 A1 WO 2006080892A1 SE 2006000133 W SE2006000133 W SE 2006000133W WO 2006080892 A1 WO2006080892 A1 WO 2006080892A1
Authority
WO
WIPO (PCT)
Prior art keywords
antenna
antenna element
ground plane
antenna according
hole
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.)
Ceased
Application number
PCT/SE2006/000133
Other languages
English (en)
Inventor
Tomas Rutfors
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of WO2006080892A1 publication Critical patent/WO2006080892A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
    • H01Q1/38—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith formed by a conductive layer on an insulating support
    • 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
    • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
    • H01Q9/0442—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with particular tuning means

Definitions

  • the present invention concerns an antenna for wireless communications placed a distance away from a ground plane .
  • the invention concerns also whip antennas that are omni directional all round its axis with a polarizations vector along its axis .
  • an antenna is to convert wire bound signals to electromagnetic signals propagating in the ambient media .
  • the design of the antenna determines the properties of this conversion. Important parameters are antenna gain, efficiency, directivity, polarisation, bandwidth and not least physical size .
  • the requirements of a wireless communications system determine the requirements of the antenna and by that what type of antenna to be used.
  • the antenna can be optimised for this application.
  • aesthetical requirements and radio requirements due to the large attenuation and reflections of radio signals in walls for instance, apply.
  • a whip antenna can have different electrical length and therefore have different radiation diagram
  • a i ⁇ -wave whip and a ⁇ -wave whip on a big ground plane have the ideal antenna gain of 2.15 dB in a plane perpendicular to the whips direction of elongation. They have also the same polarisation as the direction of elongation. If a whip is placed vertical, its polarisation also will be vertical .
  • the most common whip antennas are H-wave and H-wave antennas .
  • a ⁇ -wave antenna corresponds to one of the half of a i ⁇ -wave dipole . To get it to function it needs to be mounted on a ground plane preferable having a diameter exceeding one wave length.
  • a ⁇ -wave whip has an impedance of approximate 38 ohms at frequency of resonance when mounted on a big ground plane .
  • a ⁇ -wave whip is therefore ground plane dependent and it is necessary to adapt the antenna or the electronics so that the antenna and radio transmitter/receiver match each other to be able to function in efficient manner and giving maximal range .
  • a ⁇ -wave whip is differently designed and it has the electrical length of ⁇ s wave length. Therefore it is independent and shall not be mounted on a ground plane . If can resemble a dipole where' s connects from one side . In practice the antenna and its radiation diagram to be influenced of a ground plane in the ambient .
  • a big drawback with the is-wave whip is that they becomes fairly long, at 2.4 GHz the whip needs to be approximate 70 mm long to have the electrical length of ⁇ -wavelength.
  • One type of planar antenna is the so called patch antenna. It consist of a layer or surface of an electrically conductive material with a very small thickness compared to other dimensions, that is placed a distance, which is small compared to the wavelength, above and in parallel with a ground plane .
  • the signal to be emitted is coupled to the antenna element and the ground plane is coupled to the return conductor of the signal or ground. Since the antenna has a ground plane on one side, this side can be placed on objects without appreciably affecting its function and performance .
  • the drawback is that its surface becomes relatively large .
  • the sides of a conventional quadric patch antenna correspond to approximately ⁇ wavelength of the lowest frequency that can be emitted, witch for an antenna for 1 GHz corresponds to 17 cm. That results in it becoming unwieldy and large, in particular for frequencies below 1 GHz .
  • PIFA antennas Planar Inverted F Antenna
  • a PIFA antenna connects both with the radio signal and ground. These connect at the antenna elements edge which also is the edge of the ground plane .
  • the frequency of the antenna, the resonance frequency, is determined by the length of the antenna .
  • the antennas electrical length shall approximate be H of the wavelength at wanted frequency.
  • a common PIFA antenna has two properties that make it not useable as replacement for whip antennas . Then the antenna in general had to be connected at the edge of the ground plane it will be affected by the placement of the antenna. If the connections are placed more central on the ground plane, the antenna is difficult to be adapted to 50 ohms which usually is the common impedance for an antenna .
  • a PIFA antenna gives also a polarisation along the ground plane . It is then perpendicular to the polarisation from whip antennas . This is the most important reason that a common PIFA not can be used as replacement for whip antennas . This invention solves the problem of polarisation and impedance match of a PIFA antenna .
  • the antenna To be able to generate an electromagnetic field that both are omni directional and having a polarisation perpendicular to the ground plane, the antenna have to radiate the radio signal with a certain group of modes, the TMOx modes .
  • the mode giving the lowest frequency is the TM02 mode .
  • this mode can be emitted with good efficiency.
  • the present invention give an antenna with similar properties as H wave whips but have substantial less length and is independent of a ground plane.
  • the antenna have an integrated ground plane with a well defined distance to the antenna element which does that the antenna can be placed on arbitrary objects .
  • One spot on the antenna element connects with an electrical conductor to the radio transmitter/receiver and another spot on the antenna element connects with one or several electrical connector/s to the ground plane .
  • the antenna is consequently short circuit to ground which decrease problem with electro static discharge .
  • One antenna element shapes as a circular disc of electrically conductive material which is placed a portion from and parallel to a ground plane which is equally size or bigger than the antenna element .
  • Two different spots on the antenna element connect by electrical conductors where one spot joins to the ground plane and the other spot joins to the radio transmitter/receiver .
  • the antenna element shall have a diameter that corresponds to the electrical length of around H wave length at the present frequency.
  • the antenna element shall have at least one hole with arbitrary shape, size and placement.
  • the connection to the antenna can be model as a transmission line with impedance between 10 and 300 ohms .
  • the transmission line can have different embodiments, common types is coaxial line and pair line . Placement of the transmission line benefits to be perpendicular to the antenna element plane and at a position near the central spot and connects to the underlying ground plane with its radio transmitter or receiver .
  • the antenna element does not need to have the physical diameter of H wavelengths .
  • the antenna element can be modified to decrease the physical size with preserved electrical length. Exemplification of this is to fold the outer edge or to shape the antenna with more than one folding. It' s an advantage that the modification of the antenna elements shape is performed circularly around the central spot .
  • the antenna impedance can be adjusted. Small holes in the antenna element will not appreciable affect the antenna property. To obtain a significant change of the antenna impedance ought the holes circumference to exceed 1/8 wavelength.
  • the antenna element can in fact have arbitrary geometrical shape and give the desirable properties if the geometrical centre of gravity of the connections spots on the antenna element from one or more electrical conductors from the ground plane, essentially coincident on or near the antenna elements geometrical centre of gravity, and that the antenna element may contain at least one hole with arbitrary shape and placement and a circumference exceeding the electrical length of one tenth wavelength of emitted or received radio signal .
  • connection spot on the antenna element shall then essentially coincident or be located near the antenna elements geometrical centre of gravity. If more spots on the antenna element are connected to ground shall the total centre point of all ground connections on the antenna element be taken into account so the "geometrical centre of gravity" of all ground connections on the antenna element essentially coincident or is placed near the antenna elements geometrical centre of gravity.
  • the antenna elements geometrical centre of gravity calculates from the whole elements extension in one plane . If one of the edges is bended or folded, it shall be unfolded so the whole antenna element is flat to determine the geometrical centre of gravity.
  • the impedance match can be obtained by placing the coupling spot of the signal from radio transmitter or receiver on correct position on the antenna element .
  • the impedance match can be simplified by placing a hole in such way that the currents have to elapse a longer way between the signal coupling point and the antenna elements ground connection.
  • connections between the ground plane and antenna element is placed perpendicular to the ground plane .
  • connection of the signal from the ground plane up to the antenna element can be modelled as a transmission line with impedance between 10 and 300 ohms . It can be modelled with coaxial shape or as pair conductor . A pair conductor can both have circular and plane shapes .
  • the transmission line can also consist of more than two electrical conductors .
  • Figure 1 illustrates a cross section of the circular antenna element with a present hole and where the connection spots for ground and radio signal are placed on opposite sides of the hole .
  • Figure 2 illustrates a cross section of the circular antenna element whose edge is folded to decrease the physical size .
  • the radio signal passes through the hole and connects on opposite side of the connection of ground.
  • Figure 3 view the antenna element from above with a central placed hole where a central placed transmission line of coaxial type connects by two electrical conductors to separate directions from the centre of the hole .
  • Figure 4 illustrates a antenna element with a hole in none centre position but with a central placed transmission line of coaxial type where the two conductors are connected at separate directions in the view from the hole centre .
  • Figure 5 illustrates an antenna element similar to the one in figure 4 but from a side view.
  • Figure 6 illustrates an antenna element that connects by two connectors on separate sides of a rectangular hole .
  • Figure 7 illustrates a circular antenna element with connections by coaxial conductors where the coaxial conductor s centre is placed in the antenna elements centre and where the ground connection to the antenna element occur around the whole outer conductor
  • Figure 8 illustrates a square shaped antenna element .
  • Figure 9 illustrates a square shaped antenna element with out cut .
  • Figure 10 illustrates an antenna element with different shape .
  • Figure 11 illustrates a hole with different shape .
  • Figure 12 illustrates an antenna element which connects by pair conductors .
  • FIG. 1 a cross section across the antenna elements centre (11) at a distance (20) mainly parallel to a ground plane (10) where the ground plane have arbitrary shape and is equally or bigger size than the antenna element is illustrated.
  • the antenna element and the ground plane is separated by an electrical insulator that can consist of air, plastics, ceramics or other types of insulators .
  • a hole (12) with arbitrary shape is placed in the circular antenna element and its position, size and shape will affect the impedance of the antenna .
  • the antennas resonance frequency is determined by the antenna size .
  • To the antenna element is the signal (13) from radio transmitter or receiver connected by one or more electrical conductor/s (14 ) to the same spot (15) on the antenna element .
  • To the antenna element is also one or more electrical conductor/s (16) connected from the ground plane to the same spot (17) .
  • the antenna element can also be shaped with folded edges to decrease its physical size but keep its electrical size and thereby the same function as the antenna element in figure 1 attain.
  • Figure 2 illustrates a cross section of an antenna element that has edges folded towards the ground plane . The length on the part of folding that are perpendicular to the ground plane (24) and the antenna elements plane ought not exceed the antennas radius .
  • Figure 2 illustrates how a hole (12) has placed at a position from the antenna centre and connection of radio signal (15) and ground (17 ) is placed at separate sides of the centre of the hole .
  • Figure 3 view the antenna element from above and the electrical signals connects to the antenna element by a transmission line of coaxial type where the outer conductor (19) connects to connection spot (17 ) and where the inner conductor (21 ) connects by electrical conductor to connection spot (15) on antenna element .
  • the conductors in the coaxial cable are insulated by an electrical insulator .
  • Figure 4 illustrates how the electrical connection can be done from a central placed transmission line of coaxial type where the hole (12 ) in the antenna element is not in central position.
  • Figure 5 illustrates a side view of figure 4.
  • the mid conductor in the coaxial cable (21) connects to connection point (15) by a electrical conductor (22 ) that essentially are located in the same plane as the antenna element .
  • Figure 6 illustrates the antenna element with a rectangular hole (12 ) .
  • the hole can have arbitrary shape to reach the same properties and are in line with present invention.
  • Figure 7 illustrates a circular antenna element (11) with connection by coaxial conductor where the coaxial conductors centre is located in the antenna elements centre and where the ground connection to the antenna element is performed around the whole outer conductor (19)
  • Figure 8 illustrates a square antenna element (11 ) with a hole ( 12 ) and where connection is performed by a central located coaxial conductor .
  • Connection of ground is done in same manner as in figure 7 and by that the connection to ground on the antenna element is performed around the antenna elements geometrical centre of gravity a geometrical centre of gravity of all connection spots between ground and the antenna element that coincident with the antenna elements geometrical centre of gravity is obtained.
  • This model offer the same desired antenna property as if the ground connection is concentrated at one spot and located in the antenna elements centre of gravity and is within the scope of present invention. If the connection to ground is distributed over an area or sector or if several discrete connection points are applied it is the geometrical centre of gravity of the ground connections that essential shall coincident with the antenna elements geometrical centre of gravity.
  • Figure 9 and 10 illustrates two different geometrical embodiments of the antenna element (11 ) .
  • the antenna elements geometrical shape can be arbitrary and are within the scope of present invention when remaining conditions are fulfilled.
  • Figure 11 and 12 illustrates alternative shapes of the hole in the antenna element .
  • the holes geometrical shapes are arbitrary and are within the scope of present invention when any of the holes have an electrical length exceeding one tenth of wavelength.
  • the electrical and physical length can differ and depends of what effective dielectric constant that the electromagnetic field is affected by. If the effective dielectric constant by example is four, the electrical length will be two times the physical length.
  • Figure 12 also illustrates connection by pair conductor that connects on either side of the hole (12) where ground connections (17 ) are located in the antenna elements geometrical centre of gravity. A virtual line between the radio transmitter or receiver connection spot on the antenna element ( 15) and the antenna elements geometrical centre of gravity consequently will cross the hole (12) .
  • the antenna element does not need to be flat, it can have folded edges .
  • the antenna embodiment and its ground plane can be realized in number of ways and can have different types of electrical insulators that separate them.
  • Common isolators are air, different substrates for printed circuit boards, plastics or ceramics .
  • Common electrical conductive material for antenna and ground plane embodiments is copper, silver, different alloys containing mentioned substances .
  • the coaxial transmission line to the antenna element can be an electrical coaxial connector of arbitrary type .
  • Example of coaxial connectors is SMA, EME, BNC, TNC, SMB, etc .
  • the radio signal can, as the man skilled in the art realizes, be connected to the antenna element with direct or indirect coupling.
  • direct coupling an electrical connector is understood, and by indirect coupling a capacitive or inductive or a combination of both is understood.
  • the antenna can also, as the man skilled in the art realizes, be used in systems including several antennas for example systems to enhance antenna gain, achieving space or polarisation diversity, or for systems applying MIMO techniques, meaning that nodes in wireless systems containing more antennas both for transmitting and receiving.
  • the antenna can be used within one or more frequency bands at the same time or at different occasions .
  • the antenna can use different modes of operation which will emit different radiation pattern. It is obvious that the same antenna can operate efficient at other frequencies and use other, higher order of modes or resonance frequencies on the same antenna .
  • the present invention concerns not to a specific mode or resonance, but includes them all .
  • a parasitic element for example one or more extra layers of electric conductive material at a distance from the antenna element .
  • the parasitic element can be shaped to increase the bandwidth of the antenna or to obtain an efficient antenna at another frequency band.
  • the parasitic element can also be used for impedance matching.

Landscapes

  • Waveguide Aerials (AREA)
  • Aerials With Secondary Devices (AREA)

Abstract

Antenne pour un système de communication sans fil, qui est pourvue d'un élément d'antenne en matière conductrice, situé à une certaine distance d'un plan de sol en matière électro-conductrice, ledit élément d'antenne étant connecté au plan de sol et au signal radio et comportant au moins un trou. Des antennes de ce type émettent un champ électromagnétique omnidirectionnel à polarisation perpendiculaire au plan de sol. Ladite antenne peut remplacer les antennes-fouets du fait qu'elle est moins lourde et possède une structure plus robuste.
PCT/SE2006/000133 2005-01-31 2006-01-30 Antenne a plaque Ceased WO2006080892A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0500250A SE528148C2 (sv) 2005-01-31 2005-01-31 Cirkulär antenn
SE0500250-6 2005-01-31

Publications (1)

Publication Number Publication Date
WO2006080892A1 true WO2006080892A1 (fr) 2006-08-03

Family

ID=36740811

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2006/000133 Ceased WO2006080892A1 (fr) 2005-01-31 2006-01-30 Antenne a plaque

Country Status (2)

Country Link
SE (1) SE528148C2 (fr)
WO (1) WO2006080892A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2535983A4 (fr) * 2010-11-29 2013-09-04 Mac Technologies Inc Antenne polarisée circulairement

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0278070A1 (fr) * 1986-12-23 1988-08-17 Ball Corporation Antenne à microbande circulaire pour voiture automobile
US6278410B1 (en) * 1999-11-29 2001-08-21 Interuniversitair Microelektronica Centrum Wide frequency band planar antenna
US20030052825A1 (en) * 2001-09-17 2003-03-20 Rao Barsur Rama Spatial null steering microstrip antenna array

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0278070A1 (fr) * 1986-12-23 1988-08-17 Ball Corporation Antenne à microbande circulaire pour voiture automobile
US6278410B1 (en) * 1999-11-29 2001-08-21 Interuniversitair Microelektronica Centrum Wide frequency band planar antenna
US20030052825A1 (en) * 2001-09-17 2003-03-20 Rao Barsur Rama Spatial null steering microstrip antenna array

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2535983A4 (fr) * 2010-11-29 2013-09-04 Mac Technologies Inc Antenne polarisée circulairement

Also Published As

Publication number Publication date
SE0500250L (sv) 2006-08-01
SE528148C2 (sv) 2006-09-12

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