WO2001063693A1 - Patch antenna - Google Patents

Patch antenna Download PDF

Info

Publication number
WO2001063693A1
WO2001063693A1 PCT/SE2001/000343 SE0100343W WO0163693A1 WO 2001063693 A1 WO2001063693 A1 WO 2001063693A1 SE 0100343 W SE0100343 W SE 0100343W WO 0163693 A1 WO0163693 A1 WO 0163693A1
Authority
WO
WIPO (PCT)
Prior art keywords
patch
antenna
earth plane
feeder
antenna feeder
Prior art date
Application number
PCT/SE2001/000343
Other languages
French (fr)
Inventor
Shaofang Gong
Original Assignee
Acreo Ab
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 Acreo Ab filed Critical Acreo Ab
Priority to AU2001236273A priority Critical patent/AU2001236273A1/en
Publication of WO2001063693A1 publication Critical patent/WO2001063693A1/en

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
    • H01Q9/045—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with particular feeding means

Definitions

  • the present invention relates to a so called patch antenna.
  • a conventional patch antenna according to so called microstrip technology includes a supply conductor and a radiating so called patch which is patterned on a dielectric material situated above an earth plane.
  • the length of the patch is about one half the wavelength ( ⁇ /2) and its width is between ⁇ /2 and ⁇ .
  • One way is to feed the antenna at one of its edges, wherewith the feeder is connected directly to said edge.
  • Another way is to feed the patch from a point located inwardly of the patch periphery. This enables the antenna feeder to be provided in a layer of the carrier substrate other than the actual patch and connected to the antenna via a contact point located be- tween the antenna feeder and said point.
  • a third way is to provide an electromagnetic coupling between the antenna feeder and the patch.
  • the patch and the feeder are formed in different layers.
  • the feeder and the patch do not have a direct connection, but the coupling is attained through the electromagnetic field between the feeder and the patch.
  • the invention provides a relatively small and light patch antenna which has a bandwidth of approxi- mately 4 - 16 % and which can be integrated in a multichip module ( (MMC) or mounted on a printed circuit board (PCB).
  • MMC multichip module
  • PCB printed circuit board
  • the invention thus solves the problems associated with patch antennas, i.e. large size and small bandwidths in the low GHz-range, such as in the ISM frequency range of 2.4 GHz used in Bluetooth and wireless LAN technology.
  • the present invention thus relates to a patch antenna comprised of a multilayer substrate that includes an antenna surface, i.e. a patch, an antenna feeder extending from a signal source to said patch, and an earth plane disposed parallel with the patch but spaced therefrom, wherein the antenna feeder is generally parallel relative to the patch but in a different layer than the patch, and wherein one end of the feeder is located inwardly of the patch periphery, and wherein the invention is characterised in that the antenna feeder and the earth plane are placed on mutually different sides of the patch; and in that an additional earth plane is placed between the an- tenna feeder and the first mentioned earth plane, for co-action with said antenna feeder.
  • Figure 1 illustrates a known form of a patch antenna, in plan view
  • Figure 2 is a sectional view through the patch antenna shown in Figure 1
  • Figure 3 illustrates a patch antenna according to the invention, seen in plan view
  • Figure 4 is a sectional view of the patch antenna shown in Figure 3;
  • Figure 5 is a sectional view of a multilayer structure for the manufacture of an inventive patch antenna.
  • FIGs 1 and 2 illustrate a prior art patch antenna 1.
  • This antenna includes a patch 2 and an antenna feeder 3.
  • the antenna also includes an earth plane 4, see Figure 2.
  • the earth plane is disposed parallel with the patch but in spaced relationship therewith.
  • the antenna feeder 3 lies within a substrate 5 and the patch 2 lies on top of the substrate 5.
  • the antenna feeder extends from a signal source to said patch 2.
  • the antenna feeder 3 is generally parallel in relation to the patch 2, but disposed in a layer different to that in which the patch is disposed.
  • the end 6 of the antenna feeder 3 is located inwardly of the patch periphery.
  • FIGS 3 and 4 illustrate a patch antenna constructed in accordance with the present invention. Even this patch antenna is constructed in a multilayer substrate 7.
  • the antenna feeder 8 and the earth plane 9 are placed on mutually different sides of the patch 10. Moreover, an additional earth plane 11 is placed between the antenna feeder 8 and the first mentioned earth plane 9, for co- action with the antenna feeder. Positioning of the antenna feeder 8 above the patch 10 instead of beneath the patch as in the case of the prior art , changes the feed mode in comparison with a conventional field-powered patch antenna, resulting in a far stronger coupling between the antenna feeder and the patch. This is mainly due to the fact that in prior art technol- ogy the antenna feeder co-acts with the earth plane to a greater extent.
  • the additional earth plane 11 enables the impedance of the feeder 8 to be matched to 50 ⁇ so as to reduce refraction and to provide good capacitive coupling to the patch 10.
  • the additional earth plane 11 also enables the antenna feeder 8 to be given a smaller width than in the case of known technology, without reducing antenna gain.
  • Figure 5 is a sectional view of the different substrate layers.
  • Reference numeral 12 indicates the uppermost metal layer in which the antenna feeder is formed.
  • Refer- ence numeral 13 identifies an underlying metal layer in which the additional earth plane 11 and the patch 10 are situated.
  • the reference numeral 14 identifies the lowermost metal layer, which constitutes the earth plane 9.
  • the reference numerals 15 and 16 identify dielectric layers.
  • the additional earth plane 11 is placed in the same substrate layer 13 as the patch 10.
  • end 17 of said feeder 11 is placed in the centre point of the patch 10, so as to obtain the best coupling between feeder and patch.
  • the metal layer 12 is placed close to the metal layer 13. This will enable a good coupling to be achieved between the antenna feeder and the patch through the medium of the coupling length therebetween. Therefore, according to one preferred embodiment of the invention, the distance between the antenna feeder 12 and the layer 13 in which the patch 10 and the additional earth plane 11 are situated is about 35-50 ⁇ m.
  • the strong coupling achieved in this way lessens the requirement of a thick substrate, i.e. a long distance between the antenna feeder and the patch used in conventional patch antennas.
  • the layer 16 may have a thickness of 800 - 1000 micrometers.
  • the metal layers 12, 13 and 14 will suitably have a thickness of about 10 - 35 micrometers.
  • a suitable metal is copper, although other suitable metals may, of course, be used.
  • the present invention also enables the patch to be made smaller than conventional patches.
  • the length of the patch taken parallel with the antenna feeder is ⁇ /2 but in a direction perpendicular thereto, the inventive patch has a width of ⁇ /4, whereas a conventional patch antenna has a width of ⁇ /2.
  • ⁇ is the wave length of the centre frequency.
  • the present invention enables the patch antenna to be made smaller and thinner while providing a much greater bandwidth.
  • the inventive patch antenna also has the advantage of being compatible with the substrate process applied in the production of multi-chip modules, either laminate based (MCM-L), ceramic based (MCM-C) or in manufacturing processes using thin film techniques on different substrates (MCM-D) or in conjunction with printed circuit board (PCB) techniques.
  • MCM-L laminate based
  • MCM-C ceramic based
  • PCB printed circuit board

Landscapes

  • Waveguide Aerials (AREA)
  • Details Of Aerials (AREA)

Abstract

The present invention relates to a patch antenna constructed in a multi-layer substrate, comprising an antenna surface, i.e. a patch (10), an antenna feeder (8) extending from a signal source to said patch, and an earth plane (9) disposed parallel with the patch but in spaced relationship therewith, wherein the antenna feeder is generally parallel relative to the patch but disposed in a different layer to the patch, and wherein the end (17) of the antenna feeder is located inwardly of the periphery of the patch (10). The invention is characterised in that the antenna feeder (8) and the earth plane (9) are placed on mutually different sides of the patch (10); and in that an additional earth plane (11) is disposed between the antenna feeder (8) and said first mentioned earth plane (9), for co-action with the antenna feeder.

Description

Patch antenna
The present invention relates to a so called patch antenna.
A conventional patch antenna according to so called microstrip technology includes a supply conductor and a radiating so called patch which is patterned on a dielectric material situated above an earth plane. The length of the patch is about one half the wavelength (λ/2) and its width is between λ/2 and λ.
There are several ways to feed the patch antenna. One way is to feed the antenna at one of its edges, wherewith the feeder is connected directly to said edge. Another way is to feed the patch from a point located inwardly of the patch periphery. This enables the antenna feeder to be provided in a layer of the carrier substrate other than the actual patch and connected to the antenna via a contact point located be- tween the antenna feeder and said point.
A third way is to provide an electromagnetic coupling between the antenna feeder and the patch. In this case, the patch and the feeder are formed in different layers. In this alternative, the feeder and the patch do not have a direct connection, but the coupling is attained through the electromagnetic field between the feeder and the patch.
One drawback with patch antennas resides in their narrow bandwidth. It is difficult to obtain a bandwidth greater than about two percent with conventional patch anten- nas. The main reason for this is that the impedance varies rapidly with the frequency, due to the fact that patch antennas are resonant structures similar to parallel RLC-circuits at and around the resonance frequency. The impedance is not adapted to desired values at other frequencies. However, there are ways of increasing the bandwidth. One method in this respect is to increase the substrate thickness. Another method is to place further radiating elements along two sides of the patch. The idea of these further elements is to increase the bandwidth, by giving said elements a slightly different size to the driven patch. This makes the further elements sensitive to frequencies around the centre frequency.
However, these methods result in antennas that are larger, thicker and heavier than simple patch antennas. This is highly disadvantageous when wishing to integrate antennas in integrated radio frequency systems that shall be small in size and low in weight.
These problems are solved by means of the present invention. The invention provides a relatively small and light patch antenna which has a bandwidth of approxi- mately 4 - 16 % and which can be integrated in a multichip module ( (MMC) or mounted on a printed circuit board (PCB).
The invention thus solves the problems associated with patch antennas, i.e. large size and small bandwidths in the low GHz-range, such as in the ISM frequency range of 2.4 GHz used in Bluetooth and wireless LAN technology.
The present invention thus relates to a patch antenna comprised of a multilayer substrate that includes an antenna surface, i.e. a patch, an antenna feeder extending from a signal source to said patch, and an earth plane disposed parallel with the patch but spaced therefrom, wherein the antenna feeder is generally parallel relative to the patch but in a different layer than the patch, and wherein one end of the feeder is located inwardly of the patch periphery, and wherein the invention is characterised in that the antenna feeder and the earth plane are placed on mutually different sides of the patch; and in that an additional earth plane is placed between the an- tenna feeder and the first mentioned earth plane, for co-action with said antenna feeder.
The invention will now be described in more detail partly with reference to exempli- fying embodiments thereof shown on the accompanying drawings in which
Figure 1 illustrates a known form of a patch antenna, in plan view; Figure 2 is a sectional view through the patch antenna shown in Figure 1 ; Figure 3 illustrates a patch antenna according to the invention, seen in plan view; Figure 4 is a sectional view of the patch antenna shown in Figure 3; and
Figure 5 is a sectional view of a multilayer structure for the manufacture of an inventive patch antenna.
Figures 1 and 2 illustrate a prior art patch antenna 1. This antenna includes a patch 2 and an antenna feeder 3. The antenna also includes an earth plane 4, see Figure 2. The earth plane is disposed parallel with the patch but in spaced relationship therewith. As will be seen from Figure 2, the antenna feeder 3 lies within a substrate 5 and the patch 2 lies on top of the substrate 5. The antenna feeder extends from a signal source to said patch 2. The antenna feeder 3 is generally parallel in relation to the patch 2, but disposed in a layer different to that in which the patch is disposed. The end 6 of the antenna feeder 3 is located inwardly of the patch periphery.
Figures 3 and 4 illustrate a patch antenna constructed in accordance with the present invention. Even this patch antenna is constructed in a multilayer substrate 7.
According to the invention, the antenna feeder 8 and the earth plane 9 are placed on mutually different sides of the patch 10. Moreover, an additional earth plane 11 is placed between the antenna feeder 8 and the first mentioned earth plane 9, for co- action with the antenna feeder. Positioning of the antenna feeder 8 above the patch 10 instead of beneath the patch as in the case of the prior art , changes the feed mode in comparison with a conventional field-powered patch antenna, resulting in a far stronger coupling between the antenna feeder and the patch. This is mainly due to the fact that in prior art technol- ogy the antenna feeder co-acts with the earth plane to a greater extent.
The additional earth plane 11 enables the impedance of the feeder 8 to be matched to 50 Ω so as to reduce refraction and to provide good capacitive coupling to the patch 10. The additional earth plane 11 also enables the antenna feeder 8 to be given a smaller width than in the case of known technology, without reducing antenna gain.
Figure 5 is a sectional view of the different substrate layers. Reference numeral 12 indicates the uppermost metal layer in which the antenna feeder is formed. Refer- ence numeral 13 identifies an underlying metal layer in which the additional earth plane 11 and the patch 10 are situated. The reference numeral 14 identifies the lowermost metal layer, which constitutes the earth plane 9. The reference numerals 15 and 16 identify dielectric layers.
According to one preferred embodiment, the additional earth plane 11 is placed in the same substrate layer 13 as the patch 10.
It is preferred that the end 17 of said feeder 11 is placed in the centre point of the patch 10, so as to obtain the best coupling between feeder and patch.
It is important that the metal layer 12 is placed close to the metal layer 13. This will enable a good coupling to be achieved between the antenna feeder and the patch through the medium of the coupling length therebetween. Therefore, according to one preferred embodiment of the invention, the distance between the antenna feeder 12 and the layer 13 in which the patch 10 and the additional earth plane 11 are situated is about 35-50 μm.
The strong coupling achieved in this way lessens the requirement of a thick substrate, i.e. a long distance between the antenna feeder and the patch used in conventional patch antennas.
For example, in the case of an inventive patch antenna there is obtained with a sub- strate thickness of 0.8 - 1.0 mm a bandwidth of 4 - 10% at a frequency of 2.4 GHz.
The layer 16 may have a thickness of 800 - 1000 micrometers. The metal layers 12, 13 and 14 will suitably have a thickness of about 10 - 35 micrometers. A suitable metal is copper, although other suitable metals may, of course, be used.
The present invention also enables the patch to be made smaller than conventional patches. Compared with known technology, the length of the patch taken parallel with the antenna feeder is λ/2 but in a direction perpendicular thereto, the inventive patch has a width of λ/4, whereas a conventional patch antenna has a width of λ/2. λ is the wave length of the centre frequency.
Thus, the present invention enables the patch antenna to be made smaller and thinner while providing a much greater bandwidth.
The inventive patch antenna also has the advantage of being compatible with the substrate process applied in the production of multi-chip modules, either laminate based (MCM-L), ceramic based (MCM-C) or in manufacturing processes using thin film techniques on different substrates (MCM-D) or in conjunction with printed circuit board (PCB) techniques. Thus, the inventive patch antenna can be integrated fully in MCM-technology or PCB-technology for a fully integrated radio frequency system.
It will be obvious that the present invention solves the problems mentioned in the introduction.
Although the invention has been described above with reference to several exemplifying embodiments, it will be understood that the structural form of the antenna can be varied without departing from its function.
The present invention shall therefore not be considered to be limited to the aforede- scribed embodiments, since variations can be made within the scope of the accompanying claims.

Claims

Claims
1. A patch antenna constructed in a multi-layer substrate, comprising an antenna surface, i.e. a patch (10), an antenna feeder (8) extending from a signal source to said patch, and an earth plane (9) disposed parallel with the patch but in spaced relationship therewith, wherein the antenna feeder is generally parallel relative to the patch but disposed in a different layer to the patch, and wherein the end (17) of the antenna feeder is located inwardly of the periphery of the patch (10), and wherein the patch antenna is characterised in that the antenna feeder (8) and the earth plane (9) are placed on mutually different sides of the patch (10); and in that an additional earth plane (11) is disposed between the antenna feeder (8) and said first mentioned earth plane (9), for co-action with the antenna feeder.
2. A patch antenna according to Claim 1, characterised in that the additional earth plane (11) is disposed in the same layer in the substrate (1) as the patch (10).
3. A patch antenna according to Claim 1 or 2, characterised in that said end (17) of the antenna feeder (8) is placed at the centre point of the patch (10).
4. A patch antenna according to Claim 1, 2 or 3, characterised in that the distance between the antenna feeder (8) and the layer (13) in which the patch (10) and the additional earth plane (11) are situated is about 35 - 50 micrometers.
5. A patch antenna according to Claim 1, 2, 3 or 4, characterised in that the patch (10) has an area of λ/2 x λ 14, where λ is the wave length of the centre frequency.
6. A patch antenna according to Claim 1, 2, 3, 4 or 5, characterised in that a dielectric material is disposed between the additional earth plane (11), the patch (10) and the antenna feeder (8) respectively, and between the additional earth plane (11), the patch (10), and the first mentioned earth plane (9) respectively
PCT/SE2001/000343 2000-02-22 2001-02-16 Patch antenna WO2001063693A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001236273A AU2001236273A1 (en) 2000-02-22 2001-02-16 Patch antenna

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0000564A SE515764C2 (en) 2000-02-22 2000-02-22 Patch antenna
SE0000564-5 2000-02-22

Publications (1)

Publication Number Publication Date
WO2001063693A1 true WO2001063693A1 (en) 2001-08-30

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2001/000343 WO2001063693A1 (en) 2000-02-22 2001-02-16 Patch antenna

Country Status (3)

Country Link
AU (1) AU2001236273A1 (en)
SE (1) SE515764C2 (en)
WO (1) WO2001063693A1 (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2046530A (en) * 1979-03-12 1980-11-12 Secr Defence Microstrip antenna structure
US4761654A (en) * 1985-06-25 1988-08-02 Communications Satellite Corporation Electromagnetically coupled microstrip antennas having feeding patches capacitively coupled to feedlines
US5444453A (en) * 1993-02-02 1995-08-22 Ball Corporation Microstrip antenna structure having an air gap and method of constructing same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2046530A (en) * 1979-03-12 1980-11-12 Secr Defence Microstrip antenna structure
US4761654A (en) * 1985-06-25 1988-08-02 Communications Satellite Corporation Electromagnetically coupled microstrip antennas having feeding patches capacitively coupled to feedlines
US5444453A (en) * 1993-02-02 1995-08-22 Ball Corporation Microstrip antenna structure having an air gap and method of constructing same

Also Published As

Publication number Publication date
SE0000564D0 (en) 2000-02-22
SE515764C2 (en) 2001-10-08
SE0000564L (en) 2001-08-23
AU2001236273A1 (en) 2001-09-03

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