EP0366393A2 - Antenna for radio telephone - Google Patents

Antenna for radio telephone Download PDF

Info

Publication number
EP0366393A2
EP0366393A2 EP89310906A EP89310906A EP0366393A2 EP 0366393 A2 EP0366393 A2 EP 0366393A2 EP 89310906 A EP89310906 A EP 89310906A EP 89310906 A EP89310906 A EP 89310906A EP 0366393 A2 EP0366393 A2 EP 0366393A2
Authority
EP
European Patent Office
Prior art keywords
antenna
radio telephone
plate
racterized
cha
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Withdrawn
Application number
EP89310906A
Other languages
German (de)
French (fr)
Other versions
EP0366393A3 (en
Inventor
Timo Saarnimo
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.)
Nokia Oyj
Original Assignee
Nokia Mobile Phones Ltd
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 Nokia Mobile Phones Ltd filed Critical Nokia Mobile Phones Ltd
Publication of EP0366393A2 publication Critical patent/EP0366393A2/en
Publication of EP0366393A3 publication Critical patent/EP0366393A3/en
Withdrawn legal-status Critical Current

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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
    • H01Q1/12—Supports; Mounting means
    • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
    • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
    • H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
    • H01Q1/242—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use
    • H01Q1/243—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use with built-in antennas

Definitions

  • the present invention concerns a small-size antenna for radio telephone, comprising two parallel plates disposed at a space from one another, provided with an insulator therebetween.
  • the object of the invention is to provide a small-size antenna for a radio telephone, the matching of which with the antenna input lead is of higher order and wide-band, and said matching being maximally compact.
  • PIFA antenna Plant Inverted F-Anten­na
  • resonator antenna In conjunction with radio telephones is known in prior art the so-called PIFA antenna (Planar Inverted F-Anten­na), also referred to as resonator antenna.
  • the PIFA an­tenna is composed of two parallel conducive plates inter­connected by a conductor of appropriate width so that the capacitance between the plates is in resonance with the inductance of this conductor.
  • the antenna input lead is carried at an appropriate distance from said conductor through one of the plates to the opposite plate.
  • the an­tenna is matched to the input lead by selecting an appro­priate spacing between the input lead and the conductor connecting the plates. The input impedance is determined by said spacing.
  • the difficulty in implementing the above described PIFA antenna of prior art accordingly is that the antenna element has to be brought at the desired frequency into internal resonance which is thus determined by the capacitance of the plates and the inductance of the conductor connecting them.
  • the size of the antenna element is restricted, as owing to the other dimensions of the radio telephone, the endeavour to achieve resonance at a given frequency implies that the length or width of the conductor connecting the plates may become impractical.
  • Another drawback of the PIFA antenna is that the resonant circuit constituted by the plates and the conductor con­necting them is of the first order, and it therefore has narrow band character.
  • the object of the present invention is to provide an an­tenna which eliminates the drawbacks encountered in con­junction with the PIFA antenna and at the same time, maintains the small antenna size.
  • This object is mainly achieved in that the first plate is an electrically con­ducive plate and the second plate is an insulator plate, on one surface of which, that which is opposite with re­ference to the first plate, is provided a substantially coherent metallic layer acting as ground level, and on the other surface facing the first plate is disposed a matching circuit in such manner that it matches the antenna imped­ance to the impedance of the antenna input lead of the radio telephone.
  • the conductor connecting the plates of the PIFA antenna is eliminated, whereby the antenna element need not be in resonance and one of the antenna plates is replaced by a circuit board on which a higher-order, and therefore wide­band, matching circuit can be placed.
  • Fig. 1 is presented the construction of the PIFA antenna embodying the state of art.
  • the antenna comprises two condu­cive plates 1 and 2, wherebetween is placed an insulating layer 3.
  • the thickness of the insulating layer is l e .
  • the conducing plates 1 and 2 are interconnected with a conductor 4, its width being l j .
  • To the antenna is supplied a signal by the coaxial cable 5 serving as the feeder lead, passing through the second plate 2 and the insulating layer 3 being connected to the conducive plate 1.
  • the space between the feeder lead 5 and the lead connecting the plates is l.
  • the desired feed impedance can be selected by varying said distance.
  • the conductor 4 connect­ing the plates in the antenna design of Fig. 1 has been eliminated.
  • One of the conducive antenna plates has been replaced with a thin glass fiber circuit board 22, of which the surface lying farther away from the insulator between the plates 21 and 22 has been coated with metal. Said sur­face, which is pointing downwards in Fig. 2, acts as a ground level.
  • the matching circuit S is advantageously of one of the second order but the higher-order matching circuits may equally be used.
  • the sig­nal is carried to the antenna plate 21 through a flat-lead 24.
  • the purpose of the insulation 23 between the antenna plates is to brace the plates 21 and 22 and to keep them appropriately spaced.
  • honeycomb paper which is aramide fibre paper saturated with phenolic resin and embossed in honeycomb configuration.
  • Other appropriate insulations may equally be used.
  • the circuit board 22 is also provided with a con­nector L by which the antenna is connected to the radio components of the radio telephone.
  • the matching circuit on the plate 22 may be implemented e.g. as shown in Fig. 3.
  • the antenna feed impedance has been matched to 50 ohms with the second-order match­ing circuit of bandpass type, composed of two capacitances C1 and C2 and reactances w1L1,w2L2.
  • the electrical equiv­alent connection of the antenna plate comprises a resist­ance R and a capacitance C connected in parallel and in­ductance L in series therewith.
  • the band­width of a test specimen constructed, when connected to the telephone chassis was measured and found to be 860-­990 MHz with the standing wave ratio SWR ⁇ 2.
  • the distance of the antenna from the conducive chassis of the radio telephone affects the matching of the antenna, whereby when the chassis is essentially altered, the matching circuit has also to be redesigned.
  • the matching circuit of Fig. 3 is primarily exemplary.
  • the matching circuit and the plastic housing of the antenna, as well as the plastic materials of the radio telephone housing cause some signal attenuation.
  • the antenna matching of the invention With the antenna matching of the invention, a higher-­order, and therefore a greater, bandwidth matching is ob­tained than with the PIFA antenna, the external dimensions of the antenna being unchanged.
  • the matching is compact because the matching circuit is accomodated within the antenna. For instance, it may be mentioned that as regards bandwidth, the antenna is at the same time usable in the 900 MHz NMT network and in the E-TACS-network with 52 x 30 x 7.5 mm antenna size.
  • the antenna of the invention has also the additional ad­vantage that when the telephone is held in hand the matching improves and the useful frequency range increas­es implying that the antenna is not greatly sensitive to environmental effect.
  • the antenna constituting the object of the invention may also be so implemented that the antenna is integrated within the housing of the radio telephone in conjunction with the radio components so that no separate antenna con­nector is needed.
  • the matching circuit may then be disposed on the circuit board containing the radio components.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Telephone Set Structure (AREA)
  • Support Of Aerials (AREA)

Abstract

The present device concerns a small-size antenna for radio telephone. The antenna comprises two parallel, mu­tually spaced plates (21,22), the first plate (21) being electrically conductive and the second plate (22) being e.g. a glass fibre circuit board of which one surface is metal-­coated and on the other surface, facing the first plate (21), are disposed second or higher-order matching circuits (S) implemented with separate components.

Description

  • The present invention concerns a small-size antenna for radio telephone, comprising two parallel plates disposed at a space from one another, provided with an insulator therebetween.
  • The object of the invention is to provide a small-size antenna for a radio telephone, the matching of which with the antenna input lead is of higher order and wide-band, and said matching being maximally compact.
  • In conjunction with radio telephones is known in prior art the so-called PIFA antenna (Planar Inverted F-Anten­na), also referred to as resonator antenna. The PIFA an­tenna is composed of two parallel conducive plates inter­connected by a conductor of appropriate width so that the capacitance between the plates is in resonance with the inductance of this conductor. The antenna input lead is carried at an appropriate distance from said conductor through one of the plates to the opposite plate. The an­tenna is matched to the input lead by selecting an appro­priate spacing between the input lead and the conductor connecting the plates. The input impedance is determined by said spacing. The difficulty in implementing the above described PIFA antenna of prior art accordingly is that the antenna element has to be brought at the desired frequency into internal resonance which is thus determined by the capacitance of the plates and the inductance of the conductor connecting them. In case the size of the antenna element is restricted, as owing to the other dimensions of the radio telephone, the endeavour to achieve resonance at a given frequency implies that the length or width of the conductor connecting the plates may become impractical.
  • Another drawback of the PIFA antenna is that the resonant circuit constituted by the plates and the conductor con­necting them is of the first order, and it therefore has narrow band character.
  • The object of the present invention is to provide an an­tenna which eliminates the drawbacks encountered in con­junction with the PIFA antenna and at the same time, maintains the small antenna size. This object is mainly achieved in that the first plate is an electrically con­ducive plate and the second plate is an insulator plate, on one surface of which, that which is opposite with re­ference to the first plate, is provided a substantially coherent metallic layer acting as ground level, and on the other surface facing the first plate is disposed a matching circuit in such manner that it matches the antenna imped­ance to the impedance of the antenna input lead of the radio telephone.
  • It is thus understood that, according to the invention, the conductor connecting the plates of the PIFA antenna is eliminated, whereby the antenna element need not be in resonance and one of the antenna plates is replaced by a circuit board on which a higher-order, and therefore wide­band, matching circuit can be placed.
  • The invention is more closely described referring to the figures attached in which
    • Fig. 1 presents the design drawing of the PIFA antenna of prior art,
    • Fig. 2 presents the design drawing of the antenna of the invention,
    • Fig. 3 presents a schematic design of the matching circuit.
  • In Fig. 1 is presented the construction of the PIFA antenna embodying the state of art. The antenna comprises two condu­cive plates 1 and 2, wherebetween is placed an insulating layer 3. The thickness of the insulating layer is le. The conducing plates 1 and 2 are interconnected with a conductor 4, its width being lj. To the antenna is supplied a signal by the coaxial cable 5 serving as the feeder lead, passing through the second plate 2 and the insulating layer 3 being connected to the conducive plate 1. The space between the feeder lead 5 and the lead connecting the plates is l. The desired feed impedance can be selected by varying said distance.
  • In the antenna of the invention, the conductor 4 connect­ing the plates in the antenna design of Fig. 1 has been eliminated. One of the conducive antenna plates has been replaced with a thin glass fiber circuit board 22, of which the surface lying farther away from the insulator between the plates 21 and 22 has been coated with metal. Said sur­face, which is pointing downwards in Fig. 2, acts as a ground level. On that surface of the plate 22 which faces the insulator 23 between the plates 21 and 22, i.e. the electrically conducive plate 21, has been disposed a mat­ching circuit S including chips and its microconductor strips. The matching circuit S is advantageously of one of the second order but the higher-order matching circuits may equally be used. From the matching circuit S the sig­nal is carried to the antenna plate 21 through a flat-lead 24. The purpose of the insulation 23 between the antenna plates is to brace the plates 21 and 22 and to keep them appropriately spaced. For insulation material, so-called honeycomb paper has been used, which is aramide fibre paper saturated with phenolic resin and embossed in honeycomb configuration. Other appropriate insulations may equally be used. The circuit board 22 is also provided with a con­nector L by which the antenna is connected to the radio components of the radio telephone.
  • The matching circuit on the plate 22 may be implemented e.g. as shown in Fig. 3. Here, the antenna feed impedance has been matched to 50 ohms with the second-order match­ing circuit of bandpass type, composed of two capacitances C1 and C2 and reactances w₁L1,w₂L2. The electrical equiv­alent connection of the antenna plate comprises a resist­ance R and a capacitance C connected in parallel and in­ductance L in series therewith. In a free space, the band­width of a test specimen constructed, when connected to the telephone chassis, was measured and found to be 860-­990 MHz with the standing wave ratio SWR < 2.
  • The distance of the antenna from the conducive chassis of the radio telephone affects the matching of the antenna, whereby when the chassis is essentially altered, the matching circuit has also to be redesigned. The matching circuit of Fig. 3 is primarily exemplary. The matching circuit and the plastic housing of the antenna, as well as the plastic materials of the radio telephone housing cause some signal attenuation.
  • With the antenna matching of the invention, a higher-­order, and therefore a greater, bandwidth matching is ob­tained than with the PIFA antenna, the external dimensions of the antenna being unchanged. In addition, the matching is compact because the matching circuit is accomodated within the antenna. For instance, it may be mentioned that as regards bandwidth, the antenna is at the same time usable in the 900 MHz NMT network and in the E-TACS-network with 52 x 30 x 7.5 mm antenna size.
  • The antenna of the invention has also the additional ad­vantage that when the telephone is held in hand the matching improves and the useful frequency range increas­es implying that the antenna is not greatly sensitive to environmental effect.
  • The antenna constituting the object of the invention may also be so implemented that the antenna is integrated within the housing of the radio telephone in conjunction with the radio components so that no separate antenna con­nector is needed. The matching circuit may then be disposed on the circuit board containing the radio components. Such integration is advantageous because it is simple and there is no plastic material causing losses between the antenna element and the chassis of the radio telephone. The shape designing of the radio telephone is moreover easier as there are less external components.

Claims (8)

1. An antenna for a radio telephone, comprising opposing, parallel plates (21,22) disposed at a distance from one another, wherebetween is advantageously placed an insulating material layer (23), characterized in that the first layer (21) is an electrically conducive plate and the second plate (22) is an insulator plate, on one surface of the latter, opposite to the first plate (21), is disposed a sub­stantially uniform metal layer which acts as ground plane, and on the other surface, facing the first plate (21), is disposed a matching circuit (S) so as to match the antenna impedance with the impedance of the antenna input lead of the radio telephone.
2. Antenna for radio telephone according to claim 1, cha­racterized in that the matching circuit (S) is coupled with the first, electrically conducive plate (21) by a flat lead (24).
3. Antenna for radio telephone according to claim 1, cha­racterized in that the matching circuit (S) has been imple­mented with discrete components.
4. Antenna for radio telephone according to claim 1, cha­racterized in that the matching circuit (S) is of the second or higher order.
5. Antenna for radio telephone according to claim 1, cha­racterized in that the second plate (22) is provided with a connector for connecting the antenna to the antenna input lead.
6. Antenna for radio telephone according to claim 1, cha­racterized in that the second plate (22) is a glass fibre circuit board.
7. Antenna for radio telephone according to claim 1, cha­racterized in that the antenna has been integrated inside the housing of the radio telephone.
8. Antenna for radio telephone according to claim 7, cha­racterized in that the matching circuit (S) is located on the circuit board of the radio unit of the radio telephone.
EP19890310906 1988-10-26 1989-10-23 Antenna for radio telephone Withdrawn EP0366393A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI884945A FI81927C (en) 1988-10-26 1988-10-26 ANTENN FOER RADIO TELEPHONE.
FI884945 1988-10-26

Publications (2)

Publication Number Publication Date
EP0366393A2 true EP0366393A2 (en) 1990-05-02
EP0366393A3 EP0366393A3 (en) 1991-05-29

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ID=8527262

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890310906 Withdrawn EP0366393A3 (en) 1988-10-26 1989-10-23 Antenna for radio telephone

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EP (1) EP0366393A3 (en)
FI (1) FI81927C (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0531164A1 (en) * 1991-09-04 1993-03-10 Nec Corporation Portable radio communication apparatus
EP0537548A1 (en) * 1991-10-15 1993-04-21 Ball Corporation Microstrip antenna structure suitable for use in mobile radio communications and method for making same
WO1994018719A1 (en) * 1993-02-02 1994-08-18 Kathrein-Werke Kg Directional antenna, in particular a dipole antenna
EP0621653A2 (en) * 1993-04-23 1994-10-26 Murata Manufacturing Co., Ltd. Surface-mountable antenna unit
EP0637094A1 (en) * 1993-07-30 1995-02-01 Matsushita Electric Industrial Co., Ltd. Antenna for mobile communication
GB2281661A (en) * 1993-09-07 1995-03-08 Motorola Inc Patch antenna having integral probe and methods for constuction thereof
WO1999027607A2 (en) * 1997-11-25 1999-06-03 Lk-Products Oy Antenna structure
US5969680A (en) * 1994-10-11 1999-10-19 Murata Manufacturing Co., Ltd. Antenna device having a radiating portion provided between a wiring substrate and a case

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1981003398A1 (en) * 1980-05-13 1981-11-26 K Finken Circularly polarized hemispheric coverage flush antenna
US4320402A (en) * 1980-07-07 1982-03-16 General Dynamics Corp./Electronics Division Multiple ring microstrip antenna
EP0056923A2 (en) * 1981-01-23 1982-08-04 Thomson-Csf Antenna having small dimensions
EP0188087A1 (en) * 1984-12-18 1986-07-23 Texas Instruments Incorporated Microstrip patch antenna system
US4724443A (en) * 1985-10-31 1988-02-09 X-Cyte, Inc. Patch antenna with a strip line feed element
EP0331486A2 (en) * 1988-03-03 1989-09-06 Shaye Communications Limited Aerials

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1981003398A1 (en) * 1980-05-13 1981-11-26 K Finken Circularly polarized hemispheric coverage flush antenna
US4320402A (en) * 1980-07-07 1982-03-16 General Dynamics Corp./Electronics Division Multiple ring microstrip antenna
EP0056923A2 (en) * 1981-01-23 1982-08-04 Thomson-Csf Antenna having small dimensions
EP0188087A1 (en) * 1984-12-18 1986-07-23 Texas Instruments Incorporated Microstrip patch antenna system
US4724443A (en) * 1985-10-31 1988-02-09 X-Cyte, Inc. Patch antenna with a strip line feed element
EP0331486A2 (en) * 1988-03-03 1989-09-06 Shaye Communications Limited Aerials

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
REVIEW OF THE ELECTRICAL COMMUNICATIONS LABORATORIES vol. 35, no. 1, janvier 1987, pages 59-65, Tokyo, JP; T. TAGA et al.: "Antennas for Detachable Mobile Radio Units" *

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0531164A1 (en) * 1991-09-04 1993-03-10 Nec Corporation Portable radio communication apparatus
AU649160B2 (en) * 1991-09-04 1994-05-12 Nec Corporation Portable radio communication apparatus
EP0537548A1 (en) * 1991-10-15 1993-04-21 Ball Corporation Microstrip antenna structure suitable for use in mobile radio communications and method for making same
US5355142A (en) * 1991-10-15 1994-10-11 Ball Corporation Microstrip antenna structure suitable for use in mobile radio communications and method for making same
WO1994018719A1 (en) * 1993-02-02 1994-08-18 Kathrein-Werke Kg Directional antenna, in particular a dipole antenna
US5510802A (en) * 1993-04-23 1996-04-23 Murata Manufacturing Co., Ltd. Surface-mountable antenna unit
EP0621653A3 (en) * 1993-04-23 1995-09-20 Murata Manufacturing Co Surface-mountable antenna unit.
EP0621653A2 (en) * 1993-04-23 1994-10-26 Murata Manufacturing Co., Ltd. Surface-mountable antenna unit
EP0637094A1 (en) * 1993-07-30 1995-02-01 Matsushita Electric Industrial Co., Ltd. Antenna for mobile communication
US5526003A (en) * 1993-07-30 1996-06-11 Matsushita Electric Industrial Co., Ltd. Antenna for mobile communication
GB2281661A (en) * 1993-09-07 1995-03-08 Motorola Inc Patch antenna having integral probe and methods for constuction thereof
US5969680A (en) * 1994-10-11 1999-10-19 Murata Manufacturing Co., Ltd. Antenna device having a radiating portion provided between a wiring substrate and a case
WO1999027607A2 (en) * 1997-11-25 1999-06-03 Lk-Products Oy Antenna structure
WO1999027607A3 (en) * 1997-11-25 1999-08-12 Lk Products Oy Antenna structure

Also Published As

Publication number Publication date
FI81927C (en) 1990-12-10
FI884945A (en) 1990-04-27
EP0366393A3 (en) 1991-05-29
FI884945A0 (en) 1988-10-26
FI81927B (en) 1990-08-31

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